WO2002078320A2 - Digital halftoning - Google Patents
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- WO2002078320A2 WO2002078320A2 PCT/US2002/008954 US0208954W WO02078320A2 WO 2002078320 A2 WO2002078320 A2 WO 2002078320A2 US 0208954 W US0208954 W US 0208954W WO 02078320 A2 WO02078320 A2 WO 02078320A2
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N1/00—Scanning, transmission or reproduction of documents or the like, e.g. facsimile transmission; Details thereof
- H04N1/40—Picture signal circuits
- H04N1/405—Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels
- H04N1/4055—Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels producing a clustered dots or a size modulated halftone pattern
- H04N1/4056—Halftoning, i.e. converting the picture signal of a continuous-tone original into a corresponding signal showing only two levels producing a clustered dots or a size modulated halftone pattern the pattern varying in one dimension only, e.g. dash length, pulse width modulation [PWM]
Definitions
- the present invention relates to digital halftoning and, more particularly, to retaining high-frequency details and reducing visual artifacts in digitally- halftoned images.
- Discrete-tone output devices typically simulate continuous-tone images by producing a halftone of the continuous-tone image.
- Halftones use patterns of dots to simulate various tones. Such dot patterns tend to approximate the appearance of continuous tones when viewed by the human eye from a suitable distance.
- spa tial resolution the number of pixels within a given area
- intensi ty resolution the number of tones that may be simulated
- halftones may exhibit visual artifacts, such as Moire patterns, that reduce the perceived quality of the halftone.
- a method for producing a halftone of a source image.
- the halftone includes halftone pixels.
- the halftone pixels are suitable for containing halftone dots.
- the method selects glyphs corresponding to intensities of regions (e.g., pixels) in the source image.
- the glyphs contain one or more halftone dots.
- the method locates halftone dots within the halftone pixels such that for at least one pair of halftone dots contained within a pair of halftone pixels sharing a common boundary, the halftone dots in the pair of halftone pixels extend in opposite directions from the common boundary.
- Halftones produced by this method contain pairs of adjacent halftone dots that share a common pixel boundary. Such adjacent pairs of dots are referred to herein as dot pairs .
- each dot pair may be rendered by an output device as a single contiguous mark.
- a dot pair when rendered using a thermal printer, a dot pair may be rendered on an output medium as a single contiguous mark by printing one or more connected spots to form the dot pair. This technique results in fewer, larger dots being printed, thereby increasing the average dot perimeter-to-area ratio, which results in higher dot quality.
- the size of each dot in a dot pair is independently determined by the intensity of a unique region (e.g., a pixel) in the source image.
- a unique region e.g., a pixel
- This technique may result in greater retention of high-frequency detail than techniques that use a combination (e.g., average or sum) of multiple source image region intensities to determine the size of halftone dots.
- halftone dots generated by the method described above abut halftone pixel boundaries.
- Such a method may advantageously be used to produce higher quality halftones than those produced by methods that use dots that are centered at pixel centers.
- By rendering each pair of adjacent dots as a single contiguous mark larger dots are produced which are more robust and less susceptible to process variation that manifests itself as grain. This allows a greater number of tones to be simulated by the halftone, thereby resulting in higher- quality halftones.
- the method described above may be used to produce halftones in which halftone dots are arranged according to various angles that reduce the presence of certain visual artifacts.
- dots are arranged according to a 45-degree pattern
- spots are arranged according to a 38- degree pattern.
- each halftone dot in the halftone corresponds to the intensity of a region (e.g., a single pixel) in the source image.
- a family of glyphs is used to generate dots in the halftone.
- Each of the glyphs corresponds to a range of intensities. For each region in the source image, the glyph corresponding to the intensity of the region is selected, and the dots in the glyph are generated in the halftone at coordinates corresponding to those of the source image region.
- the intensity of each source image region is used to select the glyph corresponding to the intensity.
- a dot within the glyph is selected based on the coordinates of the source image region, and the dot is generated in the halftone at the coordinates of the source image region.
- FIGS. 1A-1E are diagrams of 2X2 glyphs for use in digital halftoning.
- FIGS. 2A-2J are diagrams of 3X3 glyphs for use in digital halftoning.
- FIG. 3A is a block diagram of a thermal-transfer print head and an output medium on which the print head is capable of printing.
- FIG. 3B is a block diagram of spots printed on an output medium by a thermal-transfer print head.
- FIG. 3C is a block diagram of variable-size spots printed on an output medium by a thermal-transfer print head.
- FIG. 4A is a block diagram of a 2X2 array of 2-bit source image pixels.
- FIG. 4B is a block diagram of a 2X2 array of halftone pixels containing dots corresponding to the source image pixels of FIG'. 4A.
- FIG. 5A is a block diagram of a 2X2 array of halftone pixels containing uniform-sized dots.
- FIG. 5B is a block diagram of four dots printed in a hexagonal pattern on an output medium.
- FIG. 5C is a block diagram of dots printed in a 45- degree pattern on an output medium.
- FIG. 5D is a block diagram of dots printed in a 45- degree pattern on an output medium, including a dot that extends across a pixel boundary.
- FIG. 5E is a block diagram of dots printed in a 45- degree pattern on an output medium, including a spurious cross-pixel dot extension.
- FIG. 6A is a block diagram of a 3X3 array of grayscale source image pixels.
- FIG. 6B is a block diagram of a 3X3 array of halftone pixels rendered on an output medium according to one embodiment of the present invention.
- FIG. 6C is a block diagram of a 3X3 array of grayscale source image pixels.
- FIG. 6D is a block diagram of a 3X3 array of halftone pixels arranged in a 45-degree pattern according to one embodiment of the present invention.
- FIG. 6E is a block diagram of a 3X3 array of halftone pixels arranged in a 38-degree pattern according to one embodiment of the present invention.
- FIG. 6F is a block diagram of a 3X3 array of halftone dot vectors used by a halftoning process according to one embodiment of the present invention.
- FIGS. 7A-7B are flow charts of a process that may be used to generate a digital halftone of a source image according to one embodiment of the present invention.
- FIG. 8A is a block diagram of a halftoning system according to one embodiment of the present invention.
- FIG. 8B is a block diagram of a halftoning system according to another embodiment of the present invention.
- FIGS. 9A-9M are glyphs in a family of glyphs that is used to perform digital halftoning according to one embodiment of the present invention.
- FIG. 10 is a block diagram of an 8-bit digital image that is logically subdivided into 2X2 subarrays of pixels.
- FIG. 11 is a flowchart of a method that is used to generate a halftone from a source image using glyphs according to one embodiment of the present invention.
- Source image refers to any continuous-tone or discrete-tone image for which a halftone is to be generated.
- FIG. 8A a general halftoning system is shown.
- a source image 800 is provided as an input to a halftoning process 802, which produces a halftone 804 corresponding to the source image 800.
- the source image 800 may, for example, be a multitone digital image stored in a computer memory or on a computer-readable medium.
- Halftone image refers to a discrete-tone image that simulates the appearance of a continuous-tone or discrete-tone source image using fewer tones than the source image.
- a halftone consists of a two-dimensional array of halftone cells, each of which consists of a two-dimensional array of halftone pixels.
- a halftone pixel may contain one or more halftone dots, and a halftone dot may consist of one or more spots.
- Halftone cell refers to a collection of halftone pixels, such as a two-dimensional array of halftone pixels.
- a halftone cell may, for example, contain a glyph or halftone pixels containing any other collection of halftone dots.
- a halftone cell is the smallest unit of a halftone that is capable of containing any glyph in the family of glyphs used in the halftone. Glyph.
- the term "glyph” refers to a pattern consisting of one or more halftone dots.
- a particular halftone typically uses a collection of glyphs, referred to herein as a "family" of glyphs, to simulate various tones.
- a glyph in a digital halftone is typically a two-dimensional array of halftone pixels containing halftone dots, and as used herein, the term glyph may refer to a single halftone dot.
- Pixel An abbreviation for "picture element,” a pixel is the smallest spatial unit of a digital image.
- a digital image is composed of a collection of pixels typically arranged in a rectangular array. Each pixel has a location, typically expressed in terms of x (column) and y (row) coordinates, and an intensity, which may represent any tone such as a color or a shade of gray. Pixels typically adjoin each other when rendered on various output media, although they may overlap or be spaced apart to various degrees when rendered.
- Various well-known techniques have been developed for representing the locations and tones of pixels.
- the source image 800 may be a digital image represented and stored as an array of pixels, referred to herein as "source image pixels" for ease of identification and explanation.
- the halftone 804 may be a digital image consisting of an array of pixels, referred to herein as halftone pixels.
- Halftone dot A halftone dot, also referred to herein simply as a "dot," consists of one or more spots.
- a thermal printer typically renders a dot as a collection of vertically-adjacent spots, while other devices may render a halftone dot as a two-dimensional array of spots.
- the resulting halftone dot may be any shape, such as a rectangle, rounded rectangle, or circle.
- Halftone dots in bilevel halftones are typically rendered as solid shapes of a uniform tone.
- a single halftone may contain halftone dots of various shapes and sizes.
- Each halftone pixel in a digital halftone may contain one or more halftone dots.
- a "physical spot,” as used herein, is a small shape, such as a rectangle or disk, that an output device has rendered at a particular point or within a particular area on an output medium.
- a physical spot is the smallest unit of output that an output device can generate.
- a physical spot may be a spot of ink printed by a printer or a pixel displayed by a monitor.
- a physical spot may be any shape, such as a rectangle, rounded rectangle, or circle.
- Different output devices may render physical spots of different shapes and sizes, and a single output device may be capable of printing physical spots of varying sizes.
- thermal-transfer printers typically pulse their heating elements to create physical spots. Each pulse of a heating element transfers a small amount of wax or ink to the output medium creating a small physical spot.
- a single heating element may be pulsed many times in succession to create many physical spots that together form a larger physical dot.
- a "logical spot,” as used herein, is a digital representation of a physical spot.
- a logical spot may be represented as, for example, a single bit in a bitmap.
- a logical spot may be stored in, for example, a computer- readable memory such as a RAM or in a file on a disk.
- spot refers to both physical spots and to logical spots.
- Point is a mathematical construct that specifies a location that may be addressed by an output device such as a printer, plotter, or monitor. With respect to images, a point is defined by two-dimensional coordinates.
- the spatial resolution of an output device indicates how many points the output device is capable of addressing in a given area. For example, a printer that has a resolution of 300 points per inch (usually expressed as 300 dots per inch or 300 dpi) , is capable of addressing (drawing spots) at 300 discrete points within an inch. Although this measure of resolution is relevant to the perceived quality of the output device's output, the perceived quality is also a function of the size of the spots that the output device prints at each point.
- addressability refers to the maximum number of individual (not necessarily distinguishable) spots per inch that an output device is capable of printing.
- the addressability of a particular output device may differ in the horizontal and vertical directions. Addressability in the x (horizontal) direction is equal to the reciprocal of the distance between the centers of spots at addresses
- Resolution refers to the number of distinguishable lines per inch that a device can create. Resolution is defined as the closest spacing at which adjacent black and white lines can be distinguished. For example, if 40 black lines interleaved with 40 white lines can be distinguished across one inch, the resolution is 80 lines per inch.
- Render refers to the process of producing output on an output medium using an output device.
- “rendering” includes printing ink or toner on a printed page, displaying pixels on a computer monitor, and storing a bitmap in RAM or other storage.
- Region As used herein, a "region" of an image may refer to any area within the image.
- a region in a digital source image may include an area containing a single pixel or a collection of pixels, such as a two- dimensional array of pixels.
- a continuous-tone image may contain any colors (tones) within a continuous range of colors.
- a grayscale image is a special kind of continuous-tone image that may contain any shades of gray within a continuous range of gray tones ranging from black to white. Conventional color and black-and-white photographs are examples of continuous-tone images.
- discrete-tone images may contain only a limited number of tones selected from a discrete set of tones.
- Computer output devices such as monitors, printers, and plotters, are only capable of rendering discrete-tone images. Such devices are therefore referred to as discrete-tone output devices or digital output devices .
- discrete-tone output devices digital output devices .
- an 8-bit grayscale image printed on an Inkjet printer may contain at most 256 (2 8 ) different shades of gray.
- a 16-bit color image displayed on a computer monitor may contain at most 65,535 (2 16 ) different colors.
- some discrete-tone output devices such as line printers, pen plotters, electrostatic plotters, some thermal printers, and some laser printers, produce output by depositing black ink or toner on an output medium such as plain paper.
- Such devices are referred to as bilevel devices because they are only capable of producing images containing two tones: a first tone (such as black) produced by depositing the ink or toner and a second tone (such as white or gray) produced by the output medium.
- Various techniques have been developed to enable bilevel devices to simulate the appearance of additional tones and thereby to produce discrete-tone images that appear similar to continuous-tone images when viewed from a suitable distance.
- the image of the photograph that is printed on the page is referred to as a half toned image or simply as a halftone .
- the photograph is considered to be composed of a two-dimensional array of small rectangular regions.
- black spots of ink are typically printed at regularly-spaced locations in the halftone corresponding to each rectangular region in the original photograph.
- the area of each ink spot in the halftone is proportional to the amount of blackness in the corresponding rectangular region in the original photograph.
- the individual ink spots produce the appearance of appropriate shades of gray, thereby simulating the appearance of the original photograph.
- Printing the halftone may be accomplished by covering the source image (e.g., a photograph) with a fine cross- hatched screen during exposure at a suitable stage in the photographic process leading to the printing plate. The result is to divide the halftone into very small, regularly spaced spots whose size varies with the image density being reproduced.
- Full-color printing is achieved by using three or four printing plates, one for each of the primary colors being used. Because undesirable Moire patterns can be produced by the interactions among the spots produced by these different screens, the screens are usually arranged at various angles to each other (referred to as screen angles) . In black-and-white bilevel halftoning, the single screen is oriented at a 45-degree angle to reduce the visibility of the halftone pattern.
- Digital output devices such as bilevel printers and plotters, can also be used to render approximations of continuous-tone images using a process referred to as digi tal halftoning (also referred to as spa tial di thering) .
- digi tal halftoning also referred to as spa tial di thering
- conventional digital halftoning typically makes use of rectangular arrays of dots (each of which may be a shape such as a rectangle or a circle) referred to as glyphs .
- glyphs When viewed from a distance, each repeated glyph pattern appears to be a different color or shade of gray. Glyphs may therefore be combined to simulate continuous-tone images.
- each of the glyphs 102a-e is a 2X2 array of halftone pixels containing a unique pattern of dots.
- These glyphs 102a-e may be used to produce the appearance of five different intensity levels (shades of gray) when viewed from an appropriate distance.
- the glyph 102a shown in FIG. 1A which contains zero dots, may be used to simulate a single white pixel in the source image.
- the glyph 102e shown in FIG. IE may be used to simulate a single black pixel in the source image.
- IB-ID may be used to simulate pixels in the source image having intermediate shades of gray.
- the glyphs 102a-e shown in FIGS. 1A-1E can be used to generate a halftone that simulates a source image by rendering, at locations in the halftone corresponding to each source image pixel, the glyph corresponding to the grayscale level of the pixel. When viewed from a suitable distance, the resulting halftone will appear similar to the source image. It should be appreciated that the grid lines shown in FIGS. 1A-1E are shown merely for purposes of illustration, and that they do not constitute parts of the glyphs and would not be rendered by an output device.
- an n X n group of bilevel pixels can be used to simulate n 2 + 1 intensity levels.
- the use of 3 X 3 glyphs 202a-202j reduces spatial resolution by a factor of three on each axis, but provides a total of 10 (3 2 + 1) intensity levels.
- a family of glyphs such as the family of glyphs 102a-e shown in FIGS. 1A-1E and the family of glyphs 202a- j shown in FIGS. 2A-2J, may be represented by a dither ma trix .
- a dither matrix is a matrix having dimensions that are equal to the dimensions of the glyphs in the family being used, and whose element values are used as threshold values to determine whether a particular glyph pixel contains a dot.
- the 2X2 glyphs 102a-e shown in FIGS. 1A-1E may be represented by a dither matrix D ⁇ 2) shown in Equation 1:
- the blackness of a pixel refers to the opposite of its intensity. For example, in an image with five gray levels, where each pixel may have an intensity, I, ranging from 0 to 4, the blackness of a pixel may also range from 0 to 4 and is equal to 4 - I.
- the blackness of the source image pixel is compared to the value of each element in the dither matrix D (2) . If the blackness of the source image pixel is greater than the element value, a dot is generated in the glyph pixel corresponding to the element. Otherwise, no dot is generated. For example, consider a pixel having an intensity of 1.
- the blackness of 3 is greater than or equal to 0 (the value of the upper-left element in the dither matrix) , so a dot is rendered in the upper-left pixel of the glyph.
- Digital halftoning may be performed by devices other than bilevel devices. For example, consider an output device that has two bits per pixel and is therefore capable of outputting pixels of four different intensity levels. If 2X2 glyphs are used, there is a total of four pixels per glyph, and each pixel may display three intensities other than black. This allows 13 (4 X 3 + 1) intensities to be simulated using the glyphs.
- Various techniques for performing halftoning using such output devices are described in Computer Graphics : Principles and Practi ce (2 nd Ed. ) , James D. Foley et al, Addison-Wesley (1997), pp. 568-574.
- the source image has fewer pixels than the output medium, so that multiple halftone pixels may be used to simulate a single pixel from the source image.
- Various techniques have also been developed for simulating a continuous-tone source image on an output medium having the same number of pixels as the source image, as will be discussed below.
- printers for printing discrete-tone images on physical output media, such as paper.
- printers include, but are not limited to, dot-matrix printers, plotters (such as pen plotters, flatbed plotters, drum plotters, desktop plotters, and electrostatic plotters) , laser printers, Inkjet printers, thermal-transfer printers, and thermal sublimation dye transfer printers.
- thermal-transfer printers contain a linear array of heating elements spaced very close together (e.g., 84.7 microns) which typically transfer colored pigments in wax from a donor sheet to plain paper.
- the wax-coated donor and plain paper are drawn together over the strip of heating elements, which are selectively heated to cause the pigment transfer.
- the wax on the donor roll may be pigmented into alternating cyan, magenta, yellow, and black strips, each of a length equal to the paper size.
- Dye sublimation printers are similar to thermal- transfer printers, except that the heating and dye transfer process permits varying intensities each of cyan, magenta, and yellow to be transferred, creating high- quality full-color images with a typical resolution of 300 dots per inch (dpi) . Although this process is slower than wax transfer, the quality of the resulting output is higher.
- Thermal-transfer printers, dye sublimation printers, and other printers that use thermal energy to deposit ink or wax on an output medium are referred to herein as thermal printers.
- a method for producing a halftone of a source image.
- the halftone includes halftone pixels.
- the halftone pixels are suitable for containing halftone dots.
- the method generates glyphs corresponding to intensities of regions (e.g., pixels) in the source image.
- the glyphs contain one or more halftone dots.
- the method positions halftone dots within the halftone pixels such that for at least one pair of halftone dots contained within two halftone pixels that are adjacent along a predetermined axis of the halftone (e.g., a horizontal or vertical axis), the halftone dots in the pair of halftone pixels extend in opposite directions from a boundary shared by the two halftone pixels.
- a print head 300 includes a linear array of heating elements 302a-d. Although only four heating elements 302a-d are shown in FIG.
- a typical thermal print head includes a large number of small heating elements that are closely spaced at, for example, 300 elements per inch.
- the print head 300 shown in block diagram form in FIG. 3A is a print head capable of printing spots of a single color (such as black)
- thermal printers may have multicolor donor ribbons capable of printing spots of multiple colors.
- the heating elements 302a-d in the print head 300 may be of any shape and size, and may be spaced apart from each other at any appropriate distances and in any configuration .
- the print head 300 is positioned over an output medium 304, such as plain paper.
- an output medium 304 such as plain paper.
- the output medium 304 moves underneath the print head 300 in. the direction indicated by arrow 306.
- a printer controller inside the thermal printer is capable of individually controlling each of the heating elements 302a-d. Activating an individual heating element causes black pigment (ink or wax) to be transferred to the area on the output medium 304 that is currently underneath the heating element, creating what is referred to herein as a spot .
- a bilevel digital image consisting of black and white pixels may be reproduced, for example, by printing spots at addresses (coordinates) on the output medium 304 corresponding to the black pixels and leaving blank the addresses corresponding to the white pixels.
- the smallest spot that may be printed by a thermal printer is approximately equal to the area of the face of each of the heating elements 302a-d.
- the output medium 304 is shown after four minimal-size spots 308a-d have been printed on the output medium 304, one by each of the heating elements 302a-d, in a diagonal pattern.
- the activated heating element will continue to transfer black pigment to the output medium 304 as long as the heating element is activated, thereby creating a larger spot.
- FIG. 3C an example is shown in which four different-sized spots 310a-d have been printed on the output medium 304, one by each of the heating elements 302a-d.
- thermal printers may be used to print digital images.
- FIG. 4A a block diagram representing an 8-bit digital source image 400 is shown.
- the digital source image consists- of a 2X2 array of 8-bit source image pixels 402a-d, each having an intensity that is in the range of 0-255.
- the source image pixel 402a which is white, has an intensity of 255
- the source image pixel 402b which is light gray
- the source image pixel 402c which is dark gray
- the source image pixel 402d which is black
- the gray source image pixels 402b and 402c are illustrated in FIG.
- a blank pattern indicates a white pixel (intensity 255)
- a single cross-hatched pattern indicates a light gray pixel (intensity 172)
- a double cross-hatched pattern indicates a dark gray pixel (intensity 86)
- a black pattern indicates a black pixel (intensity 0) .
- FIG. 4B an addressable region of the output medium 304 is structured according to a 2X2 halftone cell 410 consisting of four halftone pixels 412a-d. It should be appreciated that the halftone pixel boundary outlines are not printed on the output medium 304, but are shown merely for purposes of illustration. Each of the halftone pixels 412a-d corresponds to one of the source image pixels 402a-d (FIG. 4A) .
- halftone pixel 412a corresponds to source image pixel 402a
- halftone pixel 412b corresponds to source image pixel 402b
- halftone pixel 412c corresponds to source image pixel 402c
- halftone pixel 412d corresponds to source image pixel 402d.
- each of the halftone pixels 412a-d contains a dot that is centered within the halftone pixel and whose size is proportional to the blackness of the corresponding source image pixel.
- halftone pixel 412a does not contain a dot because the blackness of the corresponding source image pixel 402a is 0 (255 - 255) .
- a small dot 414 is centered within halftone pixel 412b, corresponding to the low blackness of the source image pixel 402b.
- a larger dot 416 is centered within halftone pixel 412c, corresponding to the higher blackness of the source image pixel 402c.
- a very large dot 418 is centered within halftone pixel 412d, corresponding to the maximal blackness of the source image pixel 402d. It should be appreciated that using the dot placement scheme shown in FIG. 4B, each of the dots "grows" outward from the center of the halftone pixel as the blackness of the source image pixel to be reproduced increases.
- Different-sized dots such as the dots 414, 416, and 418 shown in FIG. 4B, may be used to simulate different shades of gray. When viewed from a distance, dots such as the dots shown in FIG. 4B appear as different shades of gray. Larger dots appear to be darker shades of gray while smaller dots appear to be lighter shades of gray.
- thermal printers are typically limited in the sizes of spots that they are capable of printing, and as a result such printers may not be capable of printing a unique-sized spot for each possible source image pixel blackness.
- a particular thermal printer may only be capable of printing 64 different sizes of spot within a halftone pixel even though the source image to be printed may contain 256 different shades of gray. Therefore, the same size spot may be printed for source image pixels within a range of blackness .
- a rectangular pattern of dots such as that shown in FIG. 4B
- the human visual system is very sensitive to horizontal and vertical patterns.
- patterns arranged in the manner shown in FIG. 4B are particularly visible to the human eye, limiting the usefulness of such patterns for simulating shades of gray.
- the small dots that are used in such a pattern tend to be grainy due to process variation.
- closely- printed spots that are printed in such a pattern can connect to each other, resulting in the creation of a connected line where only separate spots were intended (a phenomenon known as "bridging of the dots") .
- bridging of the dots Several techniques may be used to reduce the impact of these problems .
- a 2X2 halftone cell 500 containing four halftone pixels 502a-d is shown.
- the cells 502a-d contain halftone dots 504a-d, respectively.
- each of the dots 504a-d is the same size.
- the halftone cell 500 shown in FIG. 5A is arranged according to a conventional rectangular pattern, and therefore may suffer from some of the visual artifacts described above.
- these visual artifacts may be mitigated by arranging the cells 502a-d in a hexagonal pattern, producing halftone pixels 512a-d containing dots 514a-d, respectively.
- Use of the hexagonal pattern produces less pattern visibility and bridging than the rectangular pattern shown in FIG. 5A.
- FIG. 5C Further improvement may be made by combining dots together to produce a pattern of dots at 45-degree angles as shown in FIG. 5C.
- the blacknesses of vertically-adjacent pairs of pixels in the source image are summed to produce a summed blackness value.
- a dot whose size is proportional to the summed blackness value is centered within a halftone pixel corresponding to the two source image pixels.
- the blackness values of the source image pixels corresponding to vertically-adjacent halftone pixels 502a and 502c are summed, and a dot 524a is centered within corresponding halftone pixel 522a in halftone cell 520 (FIG.
- FIG. 5C contains two empty pixels 522b and 522c, it should be appreciated that the dots 524a and 524d may grow large enough to expand into pixels 522b and 522c. For example, referring to FIG.
- dot 524e is large enough to expand into pixel 522c (and into another pixel, not shown, that is above pixel 522a) . Dot 524e therefore includes dot continuation 524f that is within pixel 522c.
- Conventional algorithms that are used to render dots, such as dot 524e, that expand into neighboring pixels sometimes produce incorrect results in the form of spurious dot continuations at halftone pixel boundaries corresponding to regions of high gradient in the source image. For example, referring to FIG. 5E, pixel 522c includes a spurious halftone dot continuation 524h.
- a halftone of a source image is produced in which halftone dots extend either upward or downward from halftone pixel boundaries, rather than outward from halftone pixel centers.
- the direction of dot extension depends on the coordinates of the halftone pixel in which the dot is printed.
- dots in vertically adjacent halftone pixels extend in opposite directions from a pixel boundary shared by the adjacent halftone pixels. Pairs of dots that extend in opposite directions from a common halftone pixel boundary are referred to herein as dot pairs .
- each pair of dots vertically- or horizontally-adjacent halftone pixels extend in opposite directions.
- bordering refers to adjacent pixels that are either within the same row or the same column.
- a dot pair is rendered as a single contiguous mark.
- a dot pair may be rendered as a single contiguous mark by a single thermal print head element.
- the mark may consist of one or more connected spots. This process for generating a halftone of a source image is described in more detail below.
- the digital source image 600 includes nine source image pixels 602a-i.
- each of the source image pixels 602a-i has an intensity of 128, which corresponds to a shade of gray approximately midway between black and white.
- a digital halftone 610 is shown that simulates the digital source image 600 according to one embodiment of the present invention.
- the digital halftone 610 consists of a 3X3 array of halftone pixels 612a-i.
- Each of the halftone pixels 612a- i corresponds to a source image region (e.g., a single source image pixel) in the digital source image 600 having corresponding coordinates.
- the halftone pixel 612a at coordinates (0, 0) corresponds to the source image pixel 602a in the digital image 600 at coordinates (0, 0) .
- Each of the halftone pixels 612a-i contains a dot whose size is proportional to the blackness B (255 - I) of the corresponding source image region.
- the dot extends either upward from the bottom boundary of the halftone pixel or downward from the top boundary of the halftone pixel, depending on the coordinates of the halftone pixel.
- each dot extends in the opposite direction from the dots in each of its four horizontal and vertical neighbors. For example, consider halftone pixel 612e. Its horizontal neighbors are halftone pixels 612d and 612f, and its vertical neighbors are halftone pixels 612b and 612h.
- the dot 614e in halftone pixel 612e therefore, extends upward from bottom boundary 617 of halftone pixel 612e, while the dots 614d, 614f, 614b, and 614h, in halftone pixels 612d, 612f, 612b, and 612h, respectively, extend in the opposite direction, namely downward from the top boundaries of their respective halftone pixels.
- a dot pair is rendered (e.g., printed) as a single contiguous mark using, for example, a single thermal print head element .
- Each of the dots 614a-i shown in FIG. 6B is the same size because each corresponds to source image pixels 602a- i having the same intensity. Dots generated by various embodiments of the present invention, however, may be of various sizes to simulate source image regions having various intensities.
- a 3X3 8-bit digital source image 620 is shown.
- the source image 620 includes nine source image pixels 622a-i.
- White source image pixels 622b, 622d, and 622i each has an intensity of 255.
- Black source image pixels 622c and 622h each has an intensity of 255.
- a halftone 630 corresponding to the source image 620 shown in FIG. 6C is shown according to one embodiment of the present invention.
- the halftone 630 consists of a 3X3 array of halftone pixels 632a-i.
- Each of the halftone pixels 632a- i corresponds to a single source image region (e.g., a single pixel) having corresponding coordinates.
- the size of each dot in the halftone 630 is proportional to the blackness of the corresponding source image region.
- halftone pixels 632b and 632d do not contain any dots (i.e., they contain dots of size zero), because they correspond to source image pixels 622b and 622d, whose blackness is zero.
- dots 634a, 634e, 634f, and 634g are half the height of the halftone pixels 632a, 632e, 632f, and 632g, respectively, because they correspond to source image pixels 622a, 622e, 622f, and 622g, respectively, whose blackness (128) is approximately half the maximum possible blackness.
- dots 634c and 634h are each the full height of halftone pixels 632c and 632h, because they correspond to source image pixels 622c and 622h having maximal blackness.
- Dots in halftone pixels 632a, 632c, 632e, 632g, and 632i extend upward from the bottom boundary of the halftone pixels, while dots in halftone pixels 632b, 632d, 632f, and 632h extend downward from the top boundary of the halftone pixels.
- FIG. 6F an example of a 3X3 array 650 of cells 652a-i containing halftone dot vectors 654a-i is shown.
- the halftone dot vectors 654a-i indicate: (1) the halftone pixel boundaries from which halftone dots 634a-i extend, and (2) the directions in which halftone dots 634a-i extend from such halftone pixel boundaries.
- halftone dot vectors sharing a common halftone pixel boundary extend in opposite directions from that boundary.
- each dot in the halftone 630 extends in a direction that is opposite to the direction of extension of dots in horizontally- and vertically-adjacent halftone pixels. This results in vertically-adjacent pairs of dots which extend outward from a common halftone pixel boundary.
- dot 634c and 634f extend outward from the common boundary 618 between halftone pixels 632c and 632f.
- dots 634e and 634h extend outward from the common boundary 617 between halftone pixels 632e and 632h.
- the dots 634a-i in the halftone 630 are arranged in a 45- degree pattern, which has various advantages that are described in more detail below.
- the vertically-adjacent dot pairs may be rendered as individual marks using, e.g., a single heating element in a thermal-transfer printer.
- the dots 634c and 634f may be printed as a single contiguous mark using, e.g., the heating element that is over the halftone pixels 632c and 632f while the output medium 304 passes under the heating element to form the shape made up of dots 634c and 634f.
- dot pairs (such as the dot pair consisting of dots 634c and 634f) may be printed as single marks
- the size of each component dot of a dot pair is independently determined by the intensity of a corresponding region in the source image, such as a source image pixel.
- the size of each of the dots 634c and 634f in the dot pair that they form is independently determined by the intensities of source image pixels 622c and 622f.
- dots are arranged in a 38-degree pattern to reduce the visibility of certain visual artifacts.
- a 3X3 halftone 640 includes halftone pixels 642a-i, which in turn contain dots 644a-i.
- the halftone 640 is compressed vertically (i.e., in the slow scan direction) compared to the halftones 610 (FIG. 6B) and 630 (FIG. 6D) .
- the dots 644a-i are arranged in a 38-degree pattern.
- dots 644g, 644e, and 644c form a line that is at a 38-degree angle to the horizontal axis of the halftone 640.
- the aspect ratio of the halftone 640 shown in FIG. 6E is different from that of the halftone 630 shown in FIG. 6D, techniques for resampling the source image to conform with the aspect ratio of the halftone 640 are well known to those of ordinary skill in the art.
- a flowchart of a process 700 that may be used to generate a digital halftone (such as the digital halftones 630 and 640) corresponding to a source image on an output medium according to one embodiment of the present invention is shown.
- the process 700 generates dots corresponding to regions (e.g., individual pixels) in the source image. Dots are positioned within halftone pixels such that pairs of halftone dots contained within bordering halftone pixels extend in opposite directions from the halftone pixel boundaries of the halftone dots (as indicated by the vectors 654a-i shown in FIG. 6F) . The size of each halftone dot generated by the method is proportional to the corresponding source image region.
- a variable DirectionStart is used to keep track of the direction in which the first dot in the current row is to extend.
- the value of DirectionStart may either be UP, indicating that the current dot is to extend upward from the bottom of a halftone pixel boundary, or DOWN, indicating that the current dot is to extend downward from the top of the halftone pixel boundary.
- the process 700 initially assigns a value of UP to the variable DirectionStart (step 702), indicating that the first dot in the halftone is to extend upward from the bottom of the first halftone pixel boundary.
- This initial value is chosen arbitrarily, and may alternatively be a value of DOWN. It should be appreciated that the values UP and DOWN may correspond to any opposing directions and do not specify a particular orientation.
- the process 700 enters into a loop over each row R in the source image (step 704).
- a variable D is used to keep track of the direction in which the current dot is to extend (either UP or DOWN) .
- the variable D is assigned the current value of DirectionStart (step 706) .
- the process 700 enters into an inner loop over each column C in the source image (step 708).
- the process 700 is now ready to process the source image pixel at coordinates (C, R) , where C is the current column and R is the current row.
- a variable BND is used to store an identifier of the boundary (either BOTTOM or TOP) of the current halftone pixel from which the current spot is to extend. If the value of D is equal to UP (step 710), a value of BOTTOM is assigned to BND (step 712). Otherwise, a value of TOP is assigned to BND (step 714).
- the blackness of the source image pixel at coordinates (C, R) is stored in a variable B (step 716) .
- the process 700 generates a dot: (1) in the halftone pixel H at coordinates (C, R) , (2) having a size proportional to B, and (3) extending in direction D from boundary BND of halftone pixel H (step 718). For example, if the source image pixel at coordinates (0, 0) has a blackness of 128, then the process 700 generates a dot extending upward from the bottom of the halftone pixel at coordinates (0, 0) having a size that is proportional to 128.
- the process 700 toggles the value of Direction (step 720) . More specifically, if the value of Direction is UP, then Direction is assigned a value of DOWN. Similarly, if the value of direction is DOWN, then Direction is assigned a value of UP. This ensures that horizontally-adjacent dots extend in different directions. Steps 710-720 are repeated for the remaining columns in row R (step 722) .
- the process 700 toggles the value of DirectionStart (step
- Steps 706-724 are repeated for the remaining rows in the source image (step 726) .
- FIGS. 7A-7B is shown merely for purposes of example and does not constitute a limitation of the present invention,
- the process 700 shown in FIGS. 7A-7B generates individual dots in both upward and downward directions.
- an output device such as a thermal printer, that renders dots only in a single direction and/or that renders multiple dots simultaneously.
- the process 700 shown in FIGS. 7A-7B generates adjoining dots in a dot pair separately, other processes that generate a single dot representing a dot pair are also within the scope of the present invention.
- the halftone generated by the process 700 may be rendered on an output medium either after the completion of the process 700 or as part of the process 700. As described in more detail below with respect to FIG. 8B, the halftone generated by the process 700 may be either a logical halftone or a physical halftone.
- each dot in the halftone corresponds to a single source image pixel.
- This correspondence is used merely for purposes of example and does not constitute a limitation of the present invention. Rather, the source image 800 may be upsampled or downsampled by any factor prior to or during the halftoning process 802. As a result, there may be • any numerical correspondence between dots in the halftone 804 and pixels in the source image 800, so long as dots in dot pairs extend from common halftone pixel boundaries.
- each pixel in the source image 800 corresponds to multiple dots in the halftone 804.
- each dot in the halftone 804 corresponds to multiple pixels in the source image 800.
- glyphs are used to simulate a larger number of grayscale tones than can be simulated using individual dots.
- FIGS. 9A-9M a family of thirteen glyphs 900a-m is shown that may be used to simulate thirteen shades of gray.
- Each of the glyphs 900a-m consists of a 2X2 array of pixels, each of which may contain a halftone dot.
- glyph 900a contains no dots.
- glyph 900a contains four dots each of size zero.
- the size of a single dot is increased, where the coordinates of the dot whose size is increased are chosen in a round-robin fashion.
- any family of glyphs may be used with various embodiments of the present invention.
- each region in the source image may be used to select one of the glyphs 900a-m.
- this range of blackness is subdivided into thirteen sub-ranges, and each of the glyphs 900a-m is assigned to one of the sub-ranges.
- the glyph corresponding to the source image pixel's blackness is generated at corresponding coordinates in the halftone.
- Various other schemes may be used to simulate tones using these glyphs.
- the source image may be downsampled, and the blackness of pixels in the downsampled source image may be used to select one of the glyphs 900a-m for use in the halftone, as described above.
- this technique allows source images to be printed on output devices that do not have a sufficiently high spatial resolution to print one glyph for each source image pixel, high-frequency detail is lost by downsampling the source image.
- a method that avoids downsampling is used to produce a halftone from a source image using the glyphs 900a-m.
- a source image 1000 is shown that consists of a 4X4 array of source image pixels.
- the source image 1000 is further logically subdivided into 2X2 arrays 1002a-d of source image pixels, as indicated by thick lines in FIG. 10.
- 2X2 arrays are chosen for purposes of example because in one embodiment of the present invention 2X2 glyphs are used to produce a halftone that simulates the source image 1000.
- a process 1100 is used to produce a halftone that simulates the source image 1000.
- the process 1100 enters into a loop over each 2X2 array A s of source image pixels (step 1102) .
- the source image 1000 (FIG. 10) contains 2X2 arrays 1002a-d.
- the process 1100 enters into an inner loop over each pixel P in the current array A s (step 1104).
- the variables X s and Y s are assigned the coordinates of the pixel P in the source image (step 1106) .
- the coordinates of the pixel in the upper-left corner of the source image 1000 are (0, 0)
- the coordinates of the pixel in the lower-right corner of the source image 1000 are (3, 3)
- the variables X A and Y A are assigned the coordinates of the pixel P relative to the upper-left corner of the array AS (step 1108) .
- the pixel in the lower-right corner of the source image 1000 has (X A , Y A ) coordinates (1, 1) relative to the upper-left corner of the array 1002d, and the pixel in the lower-left corner of the source image 1000 has coordinates (0, 1) relative to the upper-left corner of the array 1002c.
- the glyph G corresponding to the blackness of pixel P is selected (step 1110) .
- the glyph G may be selected in any of a variety of ways.
- a family of glyphs such as the family of glyphs 900a-m
- the blackness of pixel P may be used as an index in the lookup table to select the glyph G that corresponds to pixel P's blackness.
- the lookup table may, for example, represent each glyph as either: (1) a bitmap suitable for output on the output device 810, or (2) a pattern of halftone dots that is rasterized (converted into a bitmap) at a later stage.
- the glyph G may be generated on the fly by step 1110.
- step 1110 may use the dither matrix to generate the appropriate glyph G based on the blackness of pixel P.
- the dot (or dot pattern) D at coordinates (X A , Y A ) within glyph G is selected (step 1112) .
- coordinates (X A , Y A ) 'are (0, 1) if pixel P is in the lower-left hand corner of array A s , then coordinates (X A , Y A ) 'are (0, 1) .
- the dot at coordinates (0, 1) of the glyph G i.e., the dot in its lower-left hand corner) would be selected as dot D in step 1112.
- the dot D is generated (e.g., stored or rendered) at coordinates (X s , Y s ) in the halftone (step 1114). It should be appreciated that various techniques described above with respect to the process 700 (FIGS. 7A-7B) may be used to generate the dot D such that it extends in an appropriate direction from an appropriate halftone pixel boundary according to the halftone dot vectors 654a-i (FIG. 6F) . For example, in one embodiment of the present invention, dots are stored within pixels of the glyph G according to the halftone dot vectors of the array 650
- dots may be stored within the glyph G so that dots in adjacent pixels extend in opposite directions, as shown in FIG. 6F.
- the dot D is generated at coordinates (X s , Y s ) in the halftone (step 1114) by copying dot D from the glyph G, the dot D is already positioned properly within the pixel P and therefore need not be shifted to be located in accordance with the array 650 (FIG. 6F) .
- Steps 1106-1114 are repeated for the remaining pixels in the array A s (step 1116) .
- Steps 1104-1118 are repeated for the remaining pixel arrays in the source image 1000 (step 1118) .
- One advantage of using the process 1100 described above with respect to FIG. 11 is that it allows the simulation of a relatively large number of intensities, while still allowing individual source image pixels to specify the sizes of dots in the halftone. This enables a relatively large number of shades of gray to be simulated in the halftone, thereby producing more realistic halftones, while retaining high-frequency details compared to techniques that use the average intensity (or blackness) value of multiple source image pixels to generate dots or glyphs in the halftone.
- various embodiments of the present invention may be used to produce a halftone 804 from a source image 800 using a halftoning process 802.
- the halftoning process 802 receives the source image 800 as an input, processes the source image 800, and produces the halftone 804 as output.
- the source image 800 may, for example, be a continuous-tone image or a digital (discrete-tone) image acquired from any source.
- the source image 800 may undergo various preprocessing steps, such as color correction or color quantization, prior to being provided as an input to the halftoning process.
- the halftone 804 may be rendered on any output medium, such as plain paper or film.
- the halftone 804 may be digitally stored on any computer-readable medium such as a Random Access Memory (RAM), hard disk, floppy disk, or CD (such as a CD- ROM or CD-RW) .
- RAM Random Access Memory
- CD such as a CD- ROM or CD-RW
- the term "generate" when applied to a halftone includes rendering the halftone on an output medium, storing the halftone on a computer- readable medium, or both.
- FIG. 8B one example of a system 810 in which various embodiments of the present invention may be used is shown.
- An image acquisition device 812 such as a scanner, captures a source image 814 and provides the source image 814 to a computer 816 using a digital transport mechanism, such as a standard serial or parallel cable.
- the image acquisition device 812 may be any image acquisition device, such as a scanner or digital camera.
- the computer 816 optionally stores the source image 814 in a computer-readable memory, such as a Random Access Memory (RAM) or a hard disk.
- the computer 816 may also perform additional processing on the source image 814, such as reducing or enlarging the size of the source image 814, applying filters to the source image 814, or modifying the spatial or intensity resolution of the source image 814.
- the computer 816 transmits the results as a logical halftone 818 to an output device 820 such as a thermal- transfer printer 820 using a digital transport mechanism.
- the term "logical halftone” refers to a halftone that is stored on a computer-readable medium.
- the output device 820 may be any output device, such as a thermal printer, laser printer, inkjet printer, or multi-function device.
- the output device 820 renders a physical halftone 822 based on the logical halftone 818 using any of the various techniques described herein on an output medium such as paper or film.
- the term "physical halftone” refers to a halftone that has been rendered on an output medium.
- system 810 shown in FIG. 8B is provided merely for purposes of example and does not constitute a limitation of the present invention. Rather, any appropriate system may be used to implement the techniques described herein.
- features of the image acquisition device 812, the computer 816, and the output device 820 may be combined into a lesser number of devices or separated into a greater number of devices for performing the functions described above.
- individual pixels in the source image 800 contribute to (i.e., control the size of) individual dots in the halftone.
- This correspondence between individual source image pixels and halftone dots enables the halftone 804 to retain high-frequency details from the source image 800 while simulating a large number of gray levels, thereby resulting in more faithful reproduction of the source image 800.
- Another advantage of various embodiments of the present invention is that by combining dots together to form dot pairs, each such dot pair may be rendered in the halftone 804 using a single contiguous mark. This can reduce the number of dots that are output in the halftone, thereby increasing the perimeter-to-area ratio of the dots. Reduction of this parameter can result in higher- quality dots because dots produced by various output devices tend to exhibit poorer quality at the perimeter than within the perimeter.
- Various embodiments of the present invention also reduce the presence of certain visual artifacts that may be introduced by digital halftoning. For example, arranging dots at 45-degree angles (as shown in FIG. 6D) , or at a 38-degree angle, as shown in FIG. 6E, reduces the visual impact of the patterns because the human eye is better able to perceive such patterns when they result from dots arranged in a grid whose rows and columns are arranged horizontally and vertically in the field of vision.
- Various embodiments of the present invention have the further advantage that they reduce visual artifacts while still substantially retaining fine (high spatial frequency details) from the source image 800, as described above .
- intensity typically refers to the amount of light reflected from within a particular region of an image.
- intensity also refers to a value that may be used to represent a tone for a region.
- an intensity may be a value representing a shade of gray in a grayscale image or a color in a color image.
- an intensity may be represented as a scalar value.
- an intensity may be represented as an 8-bit scalar value having a range of 0-255.
- An intensity may also be represented, for example, as a floating point value having a range of 0-1.
- a halftone dot “extends” from a halftone pixel boundary if an edge of the dot abuts the halftone pixel boundary.
- the halftone dot 614b extends downward from the top boundary of the halftone pixel 612b.
- the term "extend” does not specify that a halftone dot be rendered in any direction or in any particular manner. Rather, a halftone dot that extends from a halftone pixel boundary may be rendered on an output medium in any manner.
- the halftone dot 614c extends upward from the bottom boundary of the halftone pixel 612c, the dot within halftone pixel 612c may, but need not be, rendered downward toward the bottom boundary of the halftone pixel 612c.
- dots that are "proportional" in size to the blackness of source image regions refer to dots that are "proportional" in size to the blackness of source image regions. It should be appreciated that such proportionality includes, but is not limited to, strict numerical proportionality. For example, in one embodiment of the present invention, there are n dot sizes Di - D n , and there are m levels of blackness Bi - B m . For any two dots having dot sizes D A and D B , corresponding to blacknesses B A and B B , respectively, if D B > D A , then B B > B A . Various other mappings between levels of blackness and dot size are also within the scope of the present invention. Furthermore, as used herein, the term "dot size" includes, but is not limited to, measures of size such as area and length.
- the techniques described above may be implemented, for example, in hardware, software, firmware, or any combination thereof.
- the techniques described above may be implemented in one or more computer programs executing on a programmable computer and/or printer including a processor, a storage medium readable by the processor (including, for example, volatile and nonvolatile memory and/or storage elements) , at least one input device, and at least one output device.
- Program code may be applied to data entered using the input device to perform the functions described herein and to generate output information.
- the output information may be applied to one or more output devices.
- Printers suitable for use with various embodiments of the present invention typically include a print engine and a printer controller.
- the printer controller receives print data from a host computer and generates page information, such as a logical halftone to be printed based on the print data.
- the printer controller transmits the page information to the print engine to be printed.
- the print engine performs the physical printing of the image specified by the page information on the output medium.
- Each computer program within the scope of the claims below may be implemented in any programming language, such as assembly language, machine language, a high-level procedural programming language, or an object-oriented programming language.
- the programming language may be a compiled or interpreted programming language.
- Each computer program may be implemented in a computer program product tangibly embodied in a machine- readable storage device for execution by a computer processor.
- Method steps of the invention may be performed by a computer processor executing a program tangibly embodied on a computer-readable medium to perform functions of the invention by operating on input and generating output.
Abstract
Description
Claims
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Families Citing this family (16)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US6999202B2 (en) | 2001-03-27 | 2006-02-14 | Polaroid Corporation | Method for generating a halftone of a source image |
US6842186B2 (en) * | 2001-05-30 | 2005-01-11 | Polaroid Corporation | High speed photo-printing apparatus |
JP2004527405A (en) * | 2001-05-30 | 2004-09-09 | ポラロイド コーポレーション | High-speed photo printing equipment |
US6937365B2 (en) | 2001-05-30 | 2005-08-30 | Polaroid Corporation | Rendering images utilizing adaptive error diffusion |
US6906736B2 (en) * | 2002-02-19 | 2005-06-14 | Polaroid Corporation | Technique for printing a color image |
US7548347B2 (en) * | 2002-08-28 | 2009-06-16 | Canon Kabushiki Kaisha | Image printing apparatus and image printing method |
US20040066538A1 (en) * | 2002-10-04 | 2004-04-08 | Rozzi William A. | Conversion of halftone bitmaps to continuous tone representations |
US7283666B2 (en) | 2003-02-27 | 2007-10-16 | Saquib Suhail S | Digital image exposure correction |
US8773685B2 (en) | 2003-07-01 | 2014-07-08 | Intellectual Ventures I Llc | High-speed digital image printing system |
JP2005252911A (en) * | 2004-03-08 | 2005-09-15 | Fuji Photo Film Co Ltd | Image processing method and image processor |
US7616341B2 (en) * | 2004-07-12 | 2009-11-10 | Toshiba Corporation | System and method for metadata controlled multi-configured halftone screening |
US7869094B2 (en) * | 2005-01-07 | 2011-01-11 | Mitcham Global Investments Ltd. | Selective dithering |
EP1889209A1 (en) * | 2005-05-25 | 2008-02-20 | Agfa Graphics Nv | Image processing method and apparatus for improving the image quality of a dot matrix printer |
US20090034008A1 (en) * | 2007-08-03 | 2009-02-05 | Lawrence Croft | Method for generating stochastic dither matrix |
JP5137558B2 (en) * | 2007-12-20 | 2013-02-06 | キヤノン株式会社 | Image processing apparatus and image processing method |
WO2020242463A1 (en) * | 2019-05-29 | 2020-12-03 | Hewlett-Packard Development Company, L.P. | Color surface formation by single-color 3d printing |
Family Cites Families (215)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3820133A (en) | 1972-07-24 | 1974-06-25 | C Adorney | Teaching device |
US3864708A (en) | 1973-12-04 | 1975-02-04 | Brian S Allen | Automatic photographic apparatus and postcard vending machine |
US4070587A (en) | 1975-02-14 | 1978-01-24 | Canon Kabushiki Kaisha | Energizing control system for an intermittently energized device |
US4072973A (en) | 1976-01-26 | 1978-02-07 | Mayo William D | Camera signal system for portrait taking |
US4089017A (en) | 1976-09-07 | 1978-05-09 | Polaroid Corporation | Automatic photostudio |
JPH10285390A (en) | 1997-04-03 | 1998-10-23 | Minolta Co Ltd | Image processor |
US4154523A (en) | 1977-05-31 | 1979-05-15 | Eastman Kodak Company | Exposure determination apparatus for a photographic printer |
US4168120A (en) | 1978-04-17 | 1979-09-18 | Pako Corporation | Automatic exposure corrections for photographic printer |
JPS5590383A (en) | 1978-12-27 | 1980-07-08 | Canon Inc | Thermal printer |
US4284876A (en) | 1979-04-24 | 1981-08-18 | Oki Electric Industry Co., Ltd. | Thermal printing system |
US4347518A (en) | 1979-09-04 | 1982-08-31 | Gould Inc. | Thermal array protection apparatus |
JPS6036397B2 (en) | 1980-03-31 | 1985-08-20 | 株式会社東芝 | thermal recording device |
JPS574784A (en) | 1980-06-13 | 1982-01-11 | Canon Inc | Thermal printer |
US4385302A (en) | 1980-10-16 | 1983-05-24 | Fuji Xerox Co., Ltd. | Multicolor recording apparatus |
JPS57138960A (en) | 1981-02-20 | 1982-08-27 | Fuji Xerox Co Ltd | Multicolor heat sensitive recorder |
DE3273429D1 (en) | 1981-06-19 | 1986-10-30 | Toshiba Kk | Thermal printer |
US4391535A (en) | 1981-08-10 | 1983-07-05 | Intermec Corporation | Method and apparatus for controlling the area of a thermal print medium that is exposed by a thermal printer |
JPS58150370A (en) | 1982-03-02 | 1983-09-07 | Sony Corp | Producing system of gradation signal for printer |
JPS58164368U (en) | 1982-04-26 | 1983-11-01 | 日立電子株式会社 | Television camera characteristic automatic adjustment device |
US4514738A (en) | 1982-11-22 | 1985-04-30 | Tokyo Shibaura Denki Kabushiki Kaisha | Thermal recording system |
JPS59127781A (en) | 1983-01-11 | 1984-07-23 | Fuji Xerox Co Ltd | Driving circuit for thermal head |
JPS59127781U (en) | 1983-02-16 | 1984-08-28 | 株式会社トーキン | Vibration feedback ultrasonic oscillator |
JPS59182758A (en) | 1983-04-01 | 1984-10-17 | Fuji Xerox Co Ltd | Drive circuit for thermal head |
US4540992A (en) | 1983-04-07 | 1985-09-10 | Kabushiki Kaisha Daini Seikosha | Thermal color transfer system |
US4688051A (en) | 1983-08-15 | 1987-08-18 | Ricoh Company, Ltd. | Thermal print head driving system |
JPS6085675A (en) | 1983-10-17 | 1985-05-15 | Fuji Xerox Co Ltd | Color copying machine |
JPS60101051A (en) | 1983-11-09 | 1985-06-05 | Fuji Xerox Co Ltd | Multicolor recording system |
US4563691A (en) | 1984-12-24 | 1986-01-07 | Fuji Xerox Co., Ltd. | Thermo-sensitive recording apparatus |
US4884080A (en) | 1985-01-31 | 1989-11-28 | Kabushiki Kaisha Toshiba | Color image printing apparatus |
JPH0324972Y2 (en) | 1985-02-13 | 1991-05-30 | ||
DE3688715T3 (en) * | 1985-03-30 | 1999-05-06 | Hitachi Ltd | Scanning record type printing method and its realization device. |
JPH0140371Y2 (en) | 1985-08-29 | 1989-12-04 | ||
US4686549A (en) | 1985-12-16 | 1987-08-11 | Minnesota Mining And Manufacturing Company | Receptor sheet for thermal mass transfer printing |
JPS62275768A (en) | 1986-05-24 | 1987-11-30 | Sony Corp | Printer |
US4738526A (en) | 1986-11-21 | 1988-04-19 | Autostudio Corporation | Auto-portrait photo studio |
JPS63202182A (en) | 1987-02-18 | 1988-08-22 | Olympus Optical Co Ltd | Tilted dot pattern forming method |
US4739344A (en) | 1987-02-27 | 1988-04-19 | Astro-Med, Inc. | Chart recorded having multiple thermal print heads |
JPH02139258A (en) | 1988-08-18 | 1990-05-29 | Ricoh Co Ltd | Apparatus for correcting recording density |
US5086484A (en) | 1988-08-24 | 1992-02-04 | Canon Kabushiki Kaisha | Image processing apparatus with fixed or variable threshold |
DE68927970T2 (en) * | 1988-09-08 | 1997-10-09 | Canon Kk | Point image data output device |
JPH02121853A (en) | 1988-10-31 | 1990-05-09 | Toshiba Corp | Thermal head control circuit |
JP2984009B2 (en) | 1989-02-03 | 1999-11-29 | 株式会社リコー | Thermal head drive |
JPH0813552B2 (en) | 1989-02-17 | 1996-02-14 | 松下電器産業株式会社 | Gradation printer |
JPH02289368A (en) | 1989-03-08 | 1990-11-29 | Hitachi Ltd | Printing method |
JPH02235655A (en) | 1989-03-09 | 1990-09-18 | Kyocera Corp | Driving device of thermal head |
JPH02248264A (en) | 1989-03-20 | 1990-10-04 | Fujitsu Ltd | Thermal recorder having temperature predictive constant controlling performance |
US5086306A (en) | 1989-07-19 | 1992-02-04 | Ricoh Company, Ltd. | Line head driving apparatus |
JP2523188B2 (en) | 1989-08-07 | 1996-08-07 | シャープ株式会社 | Printing control method of thermal printer |
US5045952A (en) | 1989-08-21 | 1991-09-03 | Xerox Corporation | Method for edge enhanced error diffusion |
JP2612616B2 (en) | 1989-08-31 | 1997-05-21 | 富士写真フイルム株式会社 | Method and apparatus for driving thermal head in printer |
US4933709A (en) | 1989-09-25 | 1990-06-12 | Eastman Kodak Company | Adjusting photographic printer color exposure determination algorithms |
US5285220A (en) | 1989-11-22 | 1994-02-08 | Canon Kabushiki Kaisha | Image recording apparatus with tone correction for individual recording heads |
US4962403A (en) | 1989-12-11 | 1990-10-09 | Eastman Kodak Company | Adjusting photographic printer color exposure determination algorithms |
US5046118A (en) | 1990-02-06 | 1991-09-03 | Eastman Kodak Company | Tone-scale generation method and apparatus for digital x-ray images |
US5333246A (en) | 1990-04-05 | 1994-07-26 | Seiko Epson Corporation | Page-description language interpreter for a parallel-processing system |
US5130821A (en) * | 1990-04-16 | 1992-07-14 | Eastman Kodak Company | Method and apparatus for digital halftoning employing density distribution for selection of a threshold template |
US5208684A (en) | 1990-04-26 | 1993-05-04 | Fujitsu Limited | Half-tone image processing system |
JP2969872B2 (en) | 1990-09-10 | 1999-11-02 | 株式会社ニコン | Photometric calculation device for camera |
US5323245A (en) * | 1990-09-14 | 1994-06-21 | Minnesota Mining And Manufacturing Company | Perpendicular, unequal frequency non-conventional screen patterns for electronic halftone generation |
US5268706A (en) | 1991-02-14 | 1993-12-07 | Alps Electric Co., Ltd. | Actuating control method of thermal head |
JP2957721B2 (en) | 1991-02-25 | 1999-10-06 | アルプス電気株式会社 | Thermal control method of thermal head |
US5132703A (en) | 1991-03-08 | 1992-07-21 | Yokogawa Electric Corporation | Thermal history control in a recorder using a line thermal head |
US5132709A (en) | 1991-08-26 | 1992-07-21 | Zebra Technologies Corporation | Apparatus and method for closed-loop, thermal control of printing head |
US5307425A (en) | 1991-09-02 | 1994-04-26 | Rohm Co., Ltd. | Bi-level halftone processing circuit and image processing apparatus using the same |
US5244861A (en) | 1992-01-17 | 1993-09-14 | Eastman Kodak Company | Receiving element for use in thermal dye transfer |
US5625399A (en) | 1992-01-31 | 1997-04-29 | Intermec Corporation | Method and apparatus for controlling a thermal printhead |
US5777599A (en) * | 1992-02-14 | 1998-07-07 | Oki Electric Industry Co., Ltd. | Image generation device and method using dithering |
JPH0654195A (en) | 1992-02-28 | 1994-02-25 | Eastman Kodak Co | System and method for image scanner for improvement of microfilm image quality |
JPH07205469A (en) | 1992-03-27 | 1995-08-08 | Nec Data Terminal Ltd | Thermal head |
JP3412174B2 (en) | 1992-05-21 | 2003-06-03 | 松下電器産業株式会社 | Automatic exposure control device |
JP3209797B2 (en) | 1992-07-03 | 2001-09-17 | 松下電器産業株式会社 | Gradation printer |
US5469533A (en) | 1992-07-10 | 1995-11-21 | Microsoft Corporation | Resource-oriented printer system and method of operation |
JP2850930B2 (en) | 1992-10-12 | 1999-01-27 | 日本ビクター株式会社 | Melt type thermal transfer printing system |
US5729274A (en) | 1992-11-05 | 1998-03-17 | Fuji Photo Film Co., Ltd. | Color direct thermal printing method and thermal head of thermal printer |
US5469203A (en) | 1992-11-24 | 1995-11-21 | Eastman Kodak Company | Parasitic resistance compensation for a thermal print head |
US5644351A (en) | 1992-12-04 | 1997-07-01 | Matsushita Electric Industrial Co., Ltd. | Thermal gradation printing apparatus |
JPH06183033A (en) | 1992-12-18 | 1994-07-05 | Canon Inc | Ink jet recorder |
US5450099A (en) | 1993-04-08 | 1995-09-12 | Eastman Kodak Company | Thermal line printer with staggered head segments and overlap compensation |
JP3365818B2 (en) | 1993-04-26 | 2003-01-14 | 富士写真フイルム株式会社 | Print density control method |
KR0138362B1 (en) | 1993-05-17 | 1998-05-15 | 김광호 | Thermal transfer printing apparatus and method |
DE69419826T2 (en) | 1993-05-25 | 2000-04-27 | Dainippon Printing Co Ltd | Photographic cabin |
JP3397371B2 (en) | 1993-05-27 | 2003-04-14 | キヤノン株式会社 | Recording device and recording method |
US5818474A (en) | 1993-06-30 | 1998-10-06 | Canon Kabushiki Kaisha | Ink-jet recording apparatus and method using asynchronous masks |
US5479263A (en) * | 1993-07-01 | 1995-12-26 | Xerox Corporation | Gray pixel halftone encoder |
US5623297A (en) | 1993-07-07 | 1997-04-22 | Intermec Corporation | Method and apparatus for controlling a thermal printhead |
DE4335143A1 (en) | 1993-10-15 | 1995-04-20 | Hell Ag Linotype | Method and device for converting color values |
US5956067A (en) | 1993-10-28 | 1999-09-21 | Nisca Corporation | Thermal transfer printing device and method |
US6133983A (en) | 1993-11-12 | 2000-10-17 | Eastman Kodak Company | Photographic printing method and apparatus for setting a degree of illuminant chromatic correction using inferential illuminant detection |
JP2746088B2 (en) | 1993-11-30 | 1998-04-28 | 進工業株式会社 | Thermal head device |
JP3066237B2 (en) | 1993-12-21 | 2000-07-17 | フジコピアン株式会社 | Thermal transfer material and color image forming method |
JPH07178948A (en) | 1993-12-24 | 1995-07-18 | Shinko Electric Co Ltd | Thermal printer |
DE69433608T2 (en) | 1993-12-27 | 2005-02-17 | Sharp K.K. | Grading control method and image quality improvement for a thermal printer |
US5497174A (en) | 1994-03-11 | 1996-03-05 | Xerox Corporation | Voltage drop correction for ink jet printer |
US5786900A (en) | 1994-03-23 | 1998-07-28 | Fuji Photo Film Co., Ltd. | Image recording device for recording multicolor images with dot pitch pattern randomly arranged only in the sub-scanning direction |
JP3381755B2 (en) | 1994-10-11 | 2003-03-04 | セイコーエプソン株式会社 | Method and apparatus for improved adaptive filtering and thresholding to reduce image graininess |
US5602653A (en) * | 1994-11-08 | 1997-02-11 | Xerox Corporation | Pixel pair grid halftoning for a hyperacuity printer |
US5786837A (en) | 1994-11-29 | 1998-07-28 | Agfa-Gevaert N.V. | Method and apparatus for thermal printing with voltage-drop compensation |
JP2702426B2 (en) | 1994-12-16 | 1998-01-21 | 日本電気データ機器株式会社 | Thermal head device |
JPH08169132A (en) | 1994-12-20 | 1996-07-02 | Nec Data Terminal Ltd | Thermal head device |
US5724456A (en) | 1995-03-31 | 1998-03-03 | Polaroid Corporation | Brightness adjustment of images using digital scene analysis |
US5835627A (en) | 1995-05-15 | 1998-11-10 | Higgins; Eric W. | System and method for automatically optimizing image quality and processing time |
US5694484A (en) | 1995-05-15 | 1997-12-02 | Polaroid Corporation | System and method for automatically processing image data to provide images of optimal perceptual quality |
US6128099A (en) * | 1995-06-08 | 2000-10-03 | Delabastita; Paul A. | Halftone screen generator, halftone screen and method for generating same |
US5707082A (en) | 1995-07-18 | 1998-01-13 | Moore Business Forms Inc | Thermally imaged colored baggage tags |
US6657741B1 (en) | 1995-08-07 | 2003-12-02 | Tr Systems, Inc. | Multiple print engine system with selectively distributed ripped pages |
JPH0952382A (en) | 1995-08-17 | 1997-02-25 | Fuji Photo Film Co Ltd | Method and apparatus for correcting heat accumulation |
US5812286A (en) | 1995-08-30 | 1998-09-22 | Hewlett-Packard Company | Automatic color processing to correct hue shift and incorrect exposure |
US5664253A (en) | 1995-09-12 | 1997-09-02 | Eastman Kodak Company | Stand alone photofinishing apparatus |
JP3501567B2 (en) | 1995-09-28 | 2004-03-02 | 富士写真フイルム株式会社 | Color thermal printer |
JP3523724B2 (en) | 1995-09-29 | 2004-04-26 | 東芝テック株式会社 | Thermal transfer color printer |
KR100378492B1 (en) | 1995-10-27 | 2004-05-20 | 삼성테크윈 주식회사 | Photographic printing device |
JP3783792B2 (en) | 1995-11-09 | 2006-06-07 | 富士写真フイルム株式会社 | Image processing method in photographic printer |
JPH09167129A (en) | 1995-12-19 | 1997-06-24 | Fuji Xerox Co Ltd | Network system |
US5623581A (en) | 1996-01-22 | 1997-04-22 | Apbi Interactive Kiosk Systems | Direct view interactive photo kiosk and image forming process for same |
US5913019A (en) | 1996-01-22 | 1999-06-15 | Foto Fantasy, Inc. | Direct view interactive photo kiosk and composite image forming process for same |
JP3625333B2 (en) | 1996-02-13 | 2005-03-02 | 富士写真フイルム株式会社 | Thermal image recording apparatus and recording method |
US5777638A (en) | 1996-02-22 | 1998-07-07 | Hewlett-Packard Company | Print mode to compensate for microbanding |
US5956421A (en) * | 1996-02-28 | 1999-09-21 | Canon Kabushiki Kaisha | Image processing method and apparatus for determining a binarization threshold value used for binarizing a multi-valued image and performing binarization processing |
JPH09247473A (en) | 1996-03-07 | 1997-09-19 | Minolta Co Ltd | Image forming device |
US5809164A (en) | 1996-03-07 | 1998-09-15 | Polaroid Corporation | System and method for color gamut and tone compression using an ideal mapping function |
JP3589783B2 (en) | 1996-04-11 | 2004-11-17 | 富士写真フイルム株式会社 | Thermal storage correction method and device |
US5880777A (en) | 1996-04-15 | 1999-03-09 | Massachusetts Institute Of Technology | Low-light-level imaging and image processing |
JP3426851B2 (en) * | 1996-04-30 | 2003-07-14 | 大日本スクリーン製造株式会社 | Dot forming method for multicolor printing |
US5889546A (en) | 1996-06-04 | 1999-03-30 | Shinko Electric Co., Ltd. | Heat accumulation control device for line-type thermoelectric printer |
US5809177A (en) | 1996-06-06 | 1998-09-15 | Xerox Corporation | Hybrid error diffusion pattern shifting reduction using programmable threshold perturbation |
JPH1013682A (en) | 1996-06-21 | 1998-01-16 | Nikon Corp | Image processing method |
US5668638A (en) | 1996-06-27 | 1997-09-16 | Xerox Corporation | Error diffusion method with symmetric enhancement |
JPH1076693A (en) | 1996-07-12 | 1998-03-24 | Victor Co Of Japan Ltd | Melt type thermal transfer printer and printing paper therefor |
US6128415A (en) | 1996-09-06 | 2000-10-03 | Polaroid Corporation | Device profiles for use in a digital image processing system |
US6233360B1 (en) | 1996-09-24 | 2001-05-15 | Xerox Corporation | Method and system for hybrid error diffusion processing of image information using adaptive white and black reference values |
JPH10109436A (en) | 1996-10-04 | 1998-04-28 | Seiko Denshi Kiki Kk | Color image recording method, color image recording device, and color image recording controlling method |
US5818975A (en) | 1996-10-28 | 1998-10-06 | Eastman Kodak Company | Method and apparatus for area selective exposure adjustment |
JPH10239780A (en) | 1996-12-24 | 1998-09-11 | Fuji Photo Film Co Ltd | Method and device for outputting photographic image data |
US6243133B1 (en) | 1997-03-07 | 2001-06-05 | Eastman Kodak Company | Method for automatic scene balance of digital images |
US6249315B1 (en) | 1997-03-24 | 2001-06-19 | Jack M. Holm | Strategy for pictorial digital image processing |
US5970224A (en) | 1997-04-14 | 1999-10-19 | Xerox Corporation | Multifunctional printing system with queue management |
JPH1110852A (en) | 1997-06-24 | 1999-01-19 | Fuji Photo Film Co Ltd | Multihead type printer |
JP3683387B2 (en) | 1997-08-01 | 2005-08-17 | シャープ株式会社 | Network computer built-in printer and computer network system provided with the same |
JPH1158807A (en) | 1997-08-11 | 1999-03-02 | Minolta Co Ltd | Recorder |
US6263091B1 (en) | 1997-08-22 | 2001-07-17 | International Business Machines Corporation | System and method for identifying foreground and background portions of digitized images |
JP3690082B2 (en) | 1997-09-11 | 2005-08-31 | コニカミノルタビジネステクノロジーズ株式会社 | Selection method of image forming apparatus connected to network |
US6334660B1 (en) | 1998-10-31 | 2002-01-01 | Hewlett-Packard Company | Varying the operating energy applied to an inkjet print cartridge based upon the operating conditions |
US6069982A (en) | 1997-12-23 | 2000-05-30 | Polaroid Corporation | Estimation of frequency dependence and grey-level dependence of noise in an image |
US6101000A (en) | 1998-01-30 | 2000-08-08 | Eastman Kodak Company | Photographic processing apparatus and method |
US6172768B1 (en) | 1998-02-05 | 2001-01-09 | Canon Kabushiki Kaisha | Halftoning with changeable error diffusion weights |
US6223267B1 (en) | 1998-02-26 | 2001-04-24 | Hewlett-Packard Company | Dynamically allocable RAM disk |
US6106173A (en) | 1998-03-06 | 2000-08-22 | Asahi Kogaku Kogyo Kabushiki Kaisha | Image-forming system including a plurality of thermal heads and an image-forming sheet with a plurality of types of micro-capsules |
US6226021B1 (en) | 1998-04-03 | 2001-05-01 | Alps Electric Co., Ltd. | Image forming method of thermal transfer printer |
US6760489B1 (en) | 1998-04-06 | 2004-07-06 | Seiko Epson Corporation | Apparatus and method for image data interpolation and medium on which image data interpolation program is recorded |
AU3861399A (en) | 1998-04-15 | 1999-11-01 | Hewlett-Packard Company | Distributed processing over a network |
US6204940B1 (en) | 1998-05-15 | 2001-03-20 | Hewlett-Packard Company | Digital processing of scanned negative films |
US6233069B1 (en) | 1998-05-28 | 2001-05-15 | Eastman Kodak Company | Digital photofinishing system including film under exposure gamma, scene balance, contrast normalization, and image sharpening digital image processing |
EP0961482B1 (en) | 1998-05-28 | 2007-12-12 | Eastman Kodak Company | Digital photofinishing system including digital image processing of alternative capture color photographic media |
US5995654A (en) | 1998-05-28 | 1999-11-30 | Eastman Kodak Company | Digital photofinishing system including scene balance and image sharpening digital image processing |
US6208429B1 (en) | 1998-05-29 | 2001-03-27 | Flashpoint Technology, Inc. | Method and system for band printing of rotated digital image data |
US6631208B1 (en) | 1998-05-29 | 2003-10-07 | Fuji Photo Film Co., Ltd. | Image processing method |
JP3590265B2 (en) | 1998-06-11 | 2004-11-17 | 富士写真フイルム株式会社 | Image processing method |
JP3492202B2 (en) | 1998-06-24 | 2004-02-03 | キヤノン株式会社 | Image processing method, apparatus and recording medium |
US6694051B1 (en) | 1998-06-24 | 2004-02-17 | Canon Kabushiki Kaisha | Image processing method, image processing apparatus and recording medium |
US6104468A (en) | 1998-06-29 | 2000-08-15 | Eastman Kodak Company | Image movement in a photographic laboratory |
US6462835B1 (en) | 1998-07-15 | 2002-10-08 | Kodak Polychrome Graphics, Llc | Imaging system and method |
JP3556859B2 (en) | 1998-09-08 | 2004-08-25 | 富士写真フイルム株式会社 | Image correction method, image correction device, and recording medium |
JP3754849B2 (en) | 1998-10-30 | 2006-03-15 | キヤノン株式会社 | Data communication apparatus, control method, storage medium, and image printing system |
JP3829508B2 (en) | 1998-11-27 | 2006-10-04 | セイコーエプソン株式会社 | Image processing apparatus, image processing method, and printing apparatus |
JP2000184270A (en) | 1998-12-14 | 2000-06-30 | Ricoh Co Ltd | Digital still video camera |
US6282317B1 (en) | 1998-12-31 | 2001-08-28 | Eastman Kodak Company | Method for automatic determination of main subjects in photographic images |
JP3820497B2 (en) | 1999-01-25 | 2006-09-13 | 富士写真フイルム株式会社 | Imaging apparatus and correction processing method for automatic exposure control |
JP3369497B2 (en) | 1999-01-27 | 2003-01-20 | 松下電送システム株式会社 | Terminal device and MFP |
US6276775B1 (en) | 1999-04-29 | 2001-08-21 | Hewlett-Packard Company | Variable drop mass inkjet drop generator |
US6781713B1 (en) | 1999-05-20 | 2004-08-24 | Eastman Kodak Company | Correcting exposure in a rendered digital image |
TW473696B (en) | 1999-06-29 | 2002-01-21 | Casio Computer Co Ltd | Printing apparatus and printing method |
JP2002096470A (en) | 1999-08-24 | 2002-04-02 | Canon Inc | Device for recording, nethod for controlling the same, and computer readable memory |
CN1158184C (en) | 1999-09-29 | 2004-07-21 | 精工爱普生株式会社 | Printing machine and its control method and information recording carrier |
US6425699B1 (en) | 1999-09-29 | 2002-07-30 | Hewlett-Packard Company | Use of very small advances of printing medium for improved image quality in incremental printing |
US6690488B1 (en) | 1999-09-30 | 2004-02-10 | Polaroid Corporation | Method and apparatus for estimating the spatial frequency response of a digital image acquisition system from the images it produces |
US6628899B1 (en) | 1999-10-08 | 2003-09-30 | Fuji Photo Film Co., Ltd. | Image photographing system, image processing system, and image providing system connecting them, as well as photographing camera, image editing apparatus, image order sheet for each object and method of ordering images for each object |
KR100601312B1 (en) | 1999-10-19 | 2006-07-13 | 삼성테크윈 주식회사 | Apparatus for correlating of exposure automatically of a digital still camera and method for performing the same |
WO2001031432A1 (en) | 1999-10-19 | 2001-05-03 | Electronics For Imaging, Inc. | Automatic print load balancing |
US6856416B1 (en) | 1999-11-03 | 2005-02-15 | Toshiba Tech Corporation | Dynamic load balancing for a tandem printing system |
US6650771B1 (en) | 1999-11-22 | 2003-11-18 | Eastman Kodak Company | Color management system incorporating parameter control channels |
GB2356375B (en) | 1999-11-22 | 2003-04-09 | Esselte Nv | A method of controlling a print head |
US6628826B1 (en) | 1999-11-29 | 2003-09-30 | Eastman Kodak Company | Color reproduction of images from color films |
JP4172122B2 (en) | 1999-12-02 | 2008-10-29 | ノーリツ鋼機株式会社 | Color density correction method, recording medium having recorded color density correction program, image processing apparatus, and photographic printing apparatus |
JP2001186323A (en) | 1999-12-24 | 2001-07-06 | Fuji Photo Film Co Ltd | Identification photograph system and picture on processing method |
EP1137247A3 (en) | 2000-01-28 | 2002-10-09 | Eastman Kodak Company | Photofinishing system and method |
US6537410B2 (en) | 2000-02-01 | 2003-03-25 | Polaroid Corporation | Thermal transfer recording system |
US7092116B2 (en) | 2000-06-29 | 2006-08-15 | Douglas Calaway | Method and system for processing an annotated digital photograph using a composite image |
US6762855B1 (en) | 2000-07-07 | 2004-07-13 | Eastman Kodak Company | Variable speed printing system |
US6583852B2 (en) | 2000-09-21 | 2003-06-24 | Shutterfly, Inc. | Apparatus, architecture and method for high-speed printing |
JP3740403B2 (en) | 2000-10-23 | 2006-02-01 | キヤノン株式会社 | Printing system, printing control apparatus, information processing method, control program |
EP1201449A3 (en) | 2000-10-31 | 2003-05-14 | Hewlett-Packard Company | A system and method for improving the edge quality of inkjet printouts |
JP2002160395A (en) | 2000-11-22 | 2002-06-04 | Fuji Photo Film Co Ltd | Method and device for recording image |
US7272390B1 (en) | 2000-12-19 | 2007-09-18 | Cisco Technology, Inc. | Method and system for sending facsimile transmissions from mobile devices |
US7355732B2 (en) | 2000-12-22 | 2008-04-08 | Ricoh Company, Ltd. | Printing mechanism for wireless devices |
WO2002054234A1 (en) | 2001-01-08 | 2002-07-11 | Hyperdrive Computers Limited | Computer system with operating system on a ram-disk |
JP4662401B2 (en) | 2001-02-05 | 2011-03-30 | ローム株式会社 | Printing method and thermal printer |
US7154621B2 (en) | 2001-03-20 | 2006-12-26 | Lightsurf Technologies, Inc. | Internet delivery of digitized photographs |
US6999202B2 (en) | 2001-03-27 | 2006-02-14 | Polaroid Corporation | Method for generating a halftone of a source image |
JP2004527405A (en) | 2001-05-30 | 2004-09-09 | ポラロイド コーポレーション | High-speed photo printing equipment |
US6937365B2 (en) | 2001-05-30 | 2005-08-30 | Polaroid Corporation | Rendering images utilizing adaptive error diffusion |
US6842186B2 (en) | 2001-05-30 | 2005-01-11 | Polaroid Corporation | High speed photo-printing apparatus |
JP4218229B2 (en) | 2001-06-27 | 2009-02-04 | カシオ計算機株式会社 | Imaging apparatus and exposure control method |
US6826310B2 (en) | 2001-07-06 | 2004-11-30 | Jasc Software, Inc. | Automatic contrast enhancement |
US7557950B2 (en) | 2001-07-23 | 2009-07-07 | Seiko Epson Corporation | Printing system and printing method |
JP2003036438A (en) | 2001-07-25 | 2003-02-07 | Minolta Co Ltd | Program for specifying red-eye in image, recording medium, image processor and method for specifying red- eye |
US6819347B2 (en) | 2001-08-22 | 2004-11-16 | Polaroid Corporation | Thermal response correction system |
WO2003039143A1 (en) | 2001-10-30 | 2003-05-08 | Nikon Corporation | Image accumulation apparatus, image accumulation support apparatus, image accumulation system, image control apparatus, image storage apparatus |
JP3992177B2 (en) | 2001-11-29 | 2007-10-17 | 株式会社リコー | Image processing apparatus, image processing method, and computer program |
US6906736B2 (en) | 2002-02-19 | 2005-06-14 | Polaroid Corporation | Technique for printing a color image |
ATE547248T1 (en) | 2002-02-22 | 2012-03-15 | Mitcham Global Invest Ltd | VOLTAGE CORRECTION IN THERMAL PRINTER |
JP3928704B2 (en) | 2002-02-26 | 2007-06-13 | セイコーエプソン株式会社 | Image processing apparatus, image processing method, medium storing image processing program, and image processing program |
US6956967B2 (en) | 2002-05-20 | 2005-10-18 | Eastman Kodak Company | Color transformation for processing digital images |
US7283666B2 (en) | 2003-02-27 | 2007-10-16 | Saquib Suhail S | Digital image exposure correction |
US20040179226A1 (en) | 2003-03-10 | 2004-09-16 | Burkes Theresa A. | Accelerating printing |
US8773685B2 (en) | 2003-07-01 | 2014-07-08 | Intellectual Ventures I Llc | High-speed digital image printing system |
-
2001
- 2001-03-27 US US09/817,932 patent/US6999202B2/en not_active Ceased
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2002
- 2002-03-21 EP EP02719326A patent/EP1374557A2/en not_active Ceased
- 2002-03-21 WO PCT/US2002/008954 patent/WO2002078320A2/en active Application Filing
- 2002-03-21 JP JP2002576414A patent/JP2004530344A/en not_active Withdrawn
- 2002-03-21 CA CA002442100A patent/CA2442100C/en not_active Expired - Fee Related
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2007
- 2007-08-23 JP JP2007217505A patent/JP4405535B2/en not_active Expired - Fee Related
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2008
- 2008-02-14 US US12/031,151 patent/USRE43149E1/en not_active Expired - Lifetime
Non-Patent Citations (1)
Title |
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Also Published As
Publication number | Publication date |
---|---|
JP4405535B2 (en) | 2010-01-27 |
CA2442100A1 (en) | 2002-10-03 |
USRE43149E1 (en) | 2012-01-31 |
WO2002078320A3 (en) | 2003-03-20 |
US20020159094A1 (en) | 2002-10-31 |
EP1374557A2 (en) | 2004-01-02 |
JP2004530344A (en) | 2004-09-30 |
US6999202B2 (en) | 2006-02-14 |
JP2007329967A (en) | 2007-12-20 |
CA2442100C (en) | 2007-06-19 |
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