WO2012011246A1 - 画像処理装置 - Google Patents
画像処理装置 Download PDFInfo
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- WO2012011246A1 WO2012011246A1 PCT/JP2011/003931 JP2011003931W WO2012011246A1 WO 2012011246 A1 WO2012011246 A1 WO 2012011246A1 JP 2011003931 W JP2011003931 W JP 2011003931W WO 2012011246 A1 WO2012011246 A1 WO 2012011246A1
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
- G02B27/286—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising for controlling or changing the state of polarisation, e.g. transforming one polarisation state into another
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
- H04N23/50—Constructional details
- H04N23/555—Constructional details for picking-up images in sites, inaccessible due to their dimensions or hazardous conditions, e.g. endoscopes or borescopes
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N23/00—Cameras or camera modules comprising electronic image sensors; Control thereof
- H04N23/70—Circuitry for compensating brightness variation in the scene
- H04N23/74—Circuitry for compensating brightness variation in the scene by influencing the scene brightness using illuminating means
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B23/00—Telescopes, e.g. binoculars; Periscopes; Instruments for viewing the inside of hollow bodies; Viewfinders; Optical aiming or sighting devices
- G02B23/24—Instruments or systems for viewing the inside of hollow bodies, e.g. fibrescopes
- G02B23/2476—Non-optical details, e.g. housings, mountings, supports
- G02B23/2484—Arrangements in relation to a camera or imaging device
Definitions
- the present invention relates to an image processing apparatus capable of obtaining surface unevenness information exceeding information obtained from a two-dimensional luminance image acquired by an image sensor.
- Patent Document 1 discloses an endoscope that includes a polarization irradiation unit that irradiates an object with light of a specific polarization component, and a light receiving unit, and generates a shape change image that indicates a shape change of the surface of the object. Yes.
- the light receiving unit of the endoscope receives light of the specific polarization component in the return light from the object and light of a polarization component different from the specific polarization component in the return light.
- the imaging unit disclosed in Patent Literature 1 includes an RGB color mosaic and a polarizer arranged to face three directions having different polarization transmission axes.
- Patent Document 1 describes that a polarization characteristic calculation unit can calculate a polarization direction and generate a two-dimensional distribution of surface inclination information, in particular, in order to make it easier for an observer to visually recognize surface irregularities of mucous membranes. .
- the present invention has been made to solve the above-described problems, and its main purpose is to perform image processing that can obtain polarization information in units of pixels and obtain uneven information on the surface of the subject based on the polarization information. To provide an apparatus.
- the subject is irradiated with the polarization illumination unit that sequentially irradiates the subject with three or more types of linearly polarized light having different polarization plane angles, and each of the three or more types of linearly polarized light.
- the imaging unit sequentially captures the subject and receives the return light from the subject without passing through a polarizer to acquire the luminance value, and the luminance value output from the imaging unit is shown.
- the relationship between the angle of the polarization plane and the luminance value of each pixel is obtained, and the luminance maximum angle image defined by the angle of the polarization plane that maximizes the luminance value for each pixel, and for each pixel
- a variation luminance processing unit that generates a luminance modulation degree image defined by a ratio between an amplitude of fluctuation of the luminance value and a luminance average value due to the change of the polarization plane, and the luminance maximum angle image and the luminance modulation degree image Base There are, and a normal line estimation unit for estimating the normal line of the inclined surface of the V-shaped groove on the surface of the object in pixel units.
- the normal estimation unit includes an azimuth angle processing unit that obtains a candidate for the azimuth angle of the normal from the luminance maximum angle image, and a zenith angle that obtains a zenith angle of the normal from the luminance modulation degree image.
- a processing unit, and an azimuth ambiguity processing unit that determines one azimuth angle of the normal line from the normal azimuth angle candidates.
- a normal image generation unit that generates an image of a normal estimated by the normal estimation unit is provided.
- the azimuth ambiguity processing unit selects one of the normal azimuth angle candidates based on a non-polarized luminance image corresponding to an image under non-polarized illumination or the luminance modulation degree image. Select.
- variable luminance processing unit generates the non-polarized luminance image by performing an average of a plurality of luminance images acquired by the imaging unit, and provides the non-polarized luminance image to the azimuth angle ambiguity processing unit.
- the azimuth ambiguity processing unit is configured to generate the normal line based on at least one of a spatial gradient vector of the non-polarized luminance image and a spatial gradient vector of the luminance modulation degree image. Select one of the azimuth angle candidates.
- the polarized illumination unit and the imaging unit are attached to an endoscope.
- the polarized illumination unit irradiates non-polarized light with linearly polarized light whose polarization plane sequentially changes into three or more types by transmitting the polarization plane through a polarization plane conversion element whose polarization plane is variable.
- an angle between the optical axis of the polarized illumination and the optical axis of the imaging unit is 15 ° or less.
- the imaging unit includes a monochrome imaging device or a color imaging device.
- an illumination direction setting unit for virtually changing freely the illumination direction of the subject, and a luminance image of the subject illuminated from the illumination direction based on an output of the normal estimation unit To generate.
- the polarization illumination unit includes a spectral filter that transmits a wavelength band corresponding to a reflectance at which a spectral reflectance characteristic of the surface of the subject is minimized.
- the polarized illumination unit includes a ring illumination light source that emits unpolarized light, and a ring polarization plane conversion element that converts the unpolarized light emitted from the ring illumination light source into the linearly polarized light. And a ring-type polarization plane conversion element capable of sequentially changing the angle of the polarization plane of the linearly polarized light.
- the step of sequentially irradiating the subject with three or more types of linearly polarized light with different angles of polarization planes, and when the subject is irradiated with each of the three or more types of linearly polarized light Sequentially capturing the subject, receiving the return light from the subject without passing through a polarizer, and obtaining a luminance value, and the relationship between the angle of the polarization plane and the luminance value of each pixel
- a luminance maximum angle image defined by the angle of the polarization plane that maximizes the luminance value for each pixel, and the amplitude and average luminance value of the variation of the luminance value due to the change of the polarization plane for each pixel Generating a luminance modulation degree image defined by the ratio of the image, and, based on the luminance maximum angle image and the luminance modulation degree image, an inclined surface in the V-shaped groove existing on the surface of the subject. And estimating the line in pixels.
- the image processor receives a plurality of polarized images having three or more kinds of linearly polarized light planes that illuminate the subject, and performs image processing to obtain an inclined surface in the V-shaped groove existing on the surface of the subject.
- the image processing apparatus of the present invention when the subject is irradiated with the polarization illumination unit that sequentially irradiates the subject with three or more types of linearly polarized light having different polarization plane angles, and each of the three or more types of linearly polarized light.
- a special polarization imaging device is newly developed because it is equipped with an imaging unit that sequentially captures an image of the subject and receives the return light from the subject without passing through a polarizer to acquire a luminance value. It is possible to acquire information corresponding to the maximum luminance angle image and the luminance modulation degree image simultaneously with the color image without having to do this. Then, normal information of surface irregularities is obtained from these images. Since a normal color image sensor can be used as it is, information for visually recognizing surface irregularities can be acquired without using a high-cost polarization image sensor and without degrading image quality due to moire or the like.
- the figure which shows the structural example of the image processing apparatus of this invention A diagram showing the polarization state of polarized illumination The figure which shows the structure of the image processing apparatus in Embodiment 1 of this invention. Diagram showing the operation of the polarization plane control element Definition of polarization plane angle (A) And (b) is a figure which shows the example of photosensitive cell arrangement
- the figure which shows the structure of another image processing apparatus for acquiring a color image and a polarization image The figure which shows the photosensitive cell arrangement
- FIG. 10A The figure which shows the change of the brightness pattern image by the polarization plane rotation of the polarization illumination
- (B) are diagrams in which incident light is incident on the subject surface from directly above and is reflected once.
- Graph showing luminance variation for each pixel due to polarization plane rotation of polarized illumination The figure which shows the photograph which shows the surface shape of the sample used for acquisition of the data shown to the graph of FIG. 10A
- FIG. 10B typically (A) is a figure which shows the polarization direction of polarized illumination, (b) is a figure which shows the mode of the brightness
- channel of the to-be-photographed object surface from right above. Diagram when polarized light enters the groove at ⁇ I 0 °
- FIG. 14A is a diagram in which reflected light is generated parallel to and perpendicular to the groove azimuth angle ⁇ in the state of FIG. 14A.
- Figure where non-polarized light is incident on the groove and reflected light is generated in the direction parallel to and perpendicular to the groove azimuth angle ⁇ 1 is a configuration diagram of an image processing processor according to a first embodiment of the present invention.
- Diagram of cosine function fitting from polarized luminance samples corresponding to four types of polarized illumination Diagram showing the relationship between the XYZ component of the surface normal, the azimuth angle ⁇ , and the zenith angle ⁇
- FIG. 25A The figure which shows the azimuth angle ⁇ estimation result of the normal vector of the groove of the star-shaped subject.
- the figure which shows the zenith angle (theta) estimation result of the normal vector of the groove of a star-shaped subject The figure which shows the image generation experiment result which irradiated the illumination of four directions to the normal image of the star-shaped subject
- FIG. 27A The figure which shows the structure of the image processing apparatus in Embodiment 2 of this invention. Diagram showing characteristics of optimized spectral filter The figure which shows the structure of Embodiment 3 of this invention.
- the example of the image processing apparatus includes a polarization illumination unit 120, an imaging unit 140, a variable luminance processing unit 160, and a normal estimation unit 170, as shown in FIG. 1A.
- the variable luminance processing unit 160 and the normal estimation unit 170 are included in the image processing unit 150.
- the polarization illumination unit 120 sequentially irradiates the subject 100 with three or more types of linearly polarized light having different angles of polarization planes.
- a plurality of grooves (hereinafter referred to as “grooves”) 100a exist on the surface of the subject 100 to be imaged by the present invention.
- a plurality of grooves are observed on the surface of the organ 100 of the subject 100, for example.
- the linearly polarized light is reflected by the groove 100 a existing on the surface of the subject 100 and enters the imaging unit 140.
- the imaging unit 140 sequentially images the subject 100 when the subject 100 is irradiated with each of three or more types of linearly polarized light, and receives the return light from the subject without passing through the polarizer. To get the brightness value.
- return light means light that is reflected by the surface of the subject 100 and is incident on the imaging unit 140 out of the light emitted from the polarization illumination unit 120.
- the angle between the optical axis of the polarization illumination unit 120 and the optical axis of the imaging unit 140 must not be too large. preferable.
- the angle between the optical axis of the polarization illumination unit 120 and the optical axis of the imaging unit 140 is set to 15 ° or less, for example.
- FIG. 1B is a perspective view schematically showing the polarization directions of three types of linearly polarized light having different polarization plane angles.
- the three polarization states 10, 12, and 14 shown in the figure each have polarization planes with different angles.
- a bidirectional arrow is described inside a circle schematically showing the polarization states 10, 12, and 14 in FIG. 1B. This arrow indicates the vibration direction of the electric field vector that defines the polarization plane of linearly polarized light.
- FIG. 1B shows the XYZ coordinates of the right hand system.
- the X axis and the Y axis are set in the image plane acquired by the imaging unit 140, and the direction of the Z axis is set in the line of sight (optical axis) direction.
- the plane of polarization of linearly polarized light is a plane including the optical axis that is parallel to the oscillating electric field vector.
- the vibration direction of the electric field vector of linearly polarized light is parallel to the XY plane.
- the angle ( ⁇ I) of the polarization plane is defined by the angle formed by the polarization direction (vibration direction of the electric field vector) with respect to the positive direction of the X axis. This angle ⁇ I will be described in more detail later with reference to FIG.
- the polarization illumination unit 120 sequentially irradiates the subject 100 with three or more types of linearly polarized light having different polarization plane angles, and the imaging unit 140 irradiates the subject 100 with each of the three or more types of linearly polarized light.
- the subject 100 is sequentially imaged, and at that time, the return light from the subject is received without passing through the polarizer, and the luminance value is acquired.
- variable luminance processing unit 160 obtains the relationship between the angle of the polarization plane and the luminance value of each pixel based on the signal indicating the luminance value output from the imaging unit 140, and calculates the “maximum luminance angle image” and the “luminance modulation degree”.
- the “maximum luminance angle image” is an image defined by the angle of the polarization plane that maximizes the luminance value for each pixel constituting the image obtained by imaging.
- luminance value of the pixel P (x, y) specified by a certain coordinate (x, y) is maximized when the subject 100 is irradiated with linearly polarized light having a polarization plane of 45 °
- a value of 45 ° which is the maximum luminance angle is set for the pixel P (x, y).
- luminance maximum angle image is configured by setting such a value of the maximum luminance angle in each pixel.
- the “brightness modulation degree image” is an image defined by the ratio between the amplitude of the fluctuation of the luminance value accompanying the change of the polarization plane and the average luminance value for each pixel.
- luminance modulation degree image is configured by setting such a luminance modulation degree value in each pixel.
- image in this specification means not only a luminance image that is directly recognized by human vision, but also a wide array of numerical values given to each of a plurality of pixels.
- image when one “luminance maximum angle image” is displayed, the image can be displayed with brightness according to the value of the luminance maximum angle set for each pixel of the “luminance maximum angle image”.
- the “luminance maximum angle image” expressed in this way includes a light and dark pattern that can be recognized by human vision, but this is different from a normal luminance image showing the luminance of the subject.
- images the data itself indicating various “images” may be referred to as “images”.
- the 1A estimates the normal of the inclined surface in the V-shaped groove 100a existing on the surface of the subject 100 on a pixel basis, based on the luminance maximum angle image and the luminance modulation degree image.
- the azimuth angle of the normal of the inclined surface in the V-shaped groove 100a is perpendicular to the direction in which the V-shaped groove 100a extends.
- the direction of the V-shaped groove 100a that is, the azimuth angle of the normal of the inclined surface in the V-shaped groove 100a is determined.
- the zenith angle of the normal line of the inclined surface in the V-shaped groove 100a is determined. The principle on which the normal line estimation unit 170 in the present invention estimates the normal line of the inclined surface in the V-shaped groove 100a on a pixel basis will be described in detail later.
- FIG. 1C is a diagram schematically illustrating the overall configuration of the image processing apparatus according to the first embodiment of the present invention.
- the image processing apparatus includes an endoscope 101 and a control device 102.
- the endoscope 101 includes a distal end portion 113 having an image sensor, a light guide 105, and an insertion portion 103 having a video signal line 111.
- the insertion portion 103 of the endoscope 101 is long to the left and right as shown, and has a structure that can be bent flexibly.
- the ride guide 106 can transmit light even in a bent state.
- the endoscope includes a flexible endoscope having a flexible insertion portion 103 and a rigid endoscope having an insertion portion that is not flexible as in the present embodiment.
- the insertion portion 103 has a structure that guides return light to an imaging element located behind by using a relay optical system or the like.
- the present invention can be applied to both a flexible endoscope and a rigid endoscope.
- the control device 102 includes a light source 104, an image processor 108, and a synchronization device 112.
- White non-polarized light emitted from the light source 104 is guided to the polarization plane control element 106 of the tip 113 via the light guide 105.
- the polarization plane control element 106 is composed of, for example, a polarizing plate and a liquid crystal element, and can convert non-polarized light into linearly polarized light with an arbitrary polarization plane by voltage.
- the polarization plane control element 106 is a device that can rotate the polarization plane using liquid crystal. Examples of the configuration have already been disclosed in Patent Documents 2 and 3 and Non-Patent Document 1 and the like.
- the polarization plane control element 106 can be configured by a voltage application type liquid crystal device that combines, for example, a ferroelectric liquid crystal, a polarizing film, a quarter wavelength plate, and the like.
- the polarization plane control element 106 converts non-polarized light generated by the light source 104 and passed through the light guide 105 into linearly polarized light having a polarization plane at an arbitrary angle.
- the synchronization device 112 sends an instruction to rotate the polarization plane to the polarization plane control element 106 to rotate the polarization plane of the illumination. This polarized illumination is applied to the subject through the illumination lens 107.
- the synchronization device 112 simultaneously sends a shooting start signal to the image sensor 110 to acquire an image, and performs the above processing a plurality of times.
- the return light from the subject forms an image on the image sensor 110 through the photographing lens 109.
- the image sensor 110 may be a monochrome image sensor or a single-plate color image sensor having a color mosaic.
- the imaged video signal reaches the image processor 108 via the video signal line 111.
- the light source 104, the light guide 105, the polarization plane control element 106, and the illumination lens 107 implement the polarization illumination unit 120 of FIG. 1A.
- the imaging unit 140 of FIG. 1A is realized by the photographing lens 109 and the imaging element 110.
- the variation luminance processing unit 160 and the normal estimation unit 170 in FIG. 1A are realized by the image processor 108.
- the first image is captured when the polarization plane is 0 ° state 203
- the second image is captured when the polarization plane is 45 ° state 204
- the third image is captured when the polarization plane is 90 ° state 205.
- Is a 135 ° state (the fourth image is taken at 206.
- This angle may be other than 45 °, and may be an angle obtained by dividing 180 ° by an integer of 3 or more.
- the imaging device has high sensitivity
- the exposure time can be shortened, so that the rotation angle can be set more finely.
- the time required for rotating the polarization plane ranges from a slow operation speed of about 20 (ms) to a high speed type of about 40 to 100 ( ⁇ sec). If high-speed liquid crystal is used and the sensitivity of the image sensor is increased to such an extent that imaging can be performed in this time, even if shooting is performed with polarization rotation in four directions, it has sufficient performance for shooting moving images. Is possible.
- the optical axis of the illumination lens 107 and the optical axis of the photographing lens 109 are substantially equal. This is because shadows are not generated as much as possible on the subject during observation with the endoscope.
- an unpolarized average luminance image can be generated by adding separate polarized images from the first image to the fourth image.
- FIG. 3 is a diagram showing the definition of the angle ⁇ I of the polarization plane in the polarized illumination.
- the XY coordinate system is set toward the subject.
- the angle ⁇ I of the polarization plane is defined such that the negative X-axis direction is 0 ° and the positive Y-axis direction is positive.
- the angle ⁇ I is preserved in the reflection, the angle of the polarization plane of the reflected light and the angle of the polarization plane of the incident light are the same.
- the angle ⁇ I of the polarization plane is increased or decreased, the same polarization state is repeated with a period of 180 °.
- the function having the polarization plane angle ⁇ I as a variable is a periodic function having a period of 180 °.
- the angle ⁇ I of the polarization plane in the polarized illumination may be referred to as “incident polarization plane angle”.
- FIGS. 4A and 4B are diagrams each illustrating an example of the configuration of the imaging surface of the imaging device 110.
- FIG. 4A a plurality of photosensitive cells (photodiodes) are regularly arranged in rows and columns on the imaging surface.
- a color mosaic filter that transmits three wavelengths of RGB is installed as shown in FIG.
- Each photosensitive cell generates an electrical signal according to the amount of incident light by photoelectric conversion.
- a conventional luminance image can be used as the image sensor 110.
- the surface information of the subject is acquired by imaging while rotating the polarization plane of the illumination light as linearly polarized light.
- FIG. 5 is a diagram showing such another configuration.
- a difference from the configuration of FIG. 1C is that non-polarized white light from the light source 104 is colored by the rotating color filter 501 and sequentially irradiated in time.
- the light guide 105 transmits the color illumination as it is.
- the return light from the subject is generally polarized, but the image sensor may be for a monochrome image. For this reason, for example, a monochrome polarization image pickup device using a pattern polarizer as described in Patent Document 4 can be applied.
- FIG. 6 is an example of a monochrome polarization image pickup device in which such a pattern polarizer is arranged.
- Such an imaging device can be configured by a polarization imaging device using a photonic crystal disclosed in Patent Document 4.
- the pattern polarizer of this monochrome polarization imaging device has wavelength dependence, polarized images in all the RGB wavelength bands cannot be obtained. For example, if the pattern polarizer is designed to correspond to the B wavelength range, only the B polarization image can be obtained. Furthermore, in order to obtain a polarization image, in particular, a polarization degree and a polarization angle, a spatial kind of difference operation in a 2 ⁇ 2 cell is performed on the spatially processed image of the polarization mosaic. It is inevitable that moire occurs in the polarization image. The occurrence of moiré in the case of using this pattern polarizer is mainly caused by spatial image processing for obtaining a polarized image as described above, unlike moiré by simple pixel sampling. It has been found that this is significantly more significant than the occurrence of moiré in pixel sampling. As described above, in the configuration of FIG. 5, the image quality in polarization observation is greatly deteriorated.
- polarization information can be obtained in units of one pixel using a normal image sensor, and this problem is avoided. That is, the imaging unit in the present embodiment receives the return light without passing through the polarizer and outputs a signal indicating the luminance value. Furthermore, a polarized image is obtained with each color RGB wavelength component. There is no need for an expensive polarization imaging device.
- the subject is not an organism mucous membrane but an object of a general material such as plastic or wood. This is because the reflection on the mucosal surface is basically a specular reflection, and the reflection can be regarded as the same physical phenomenon without depending on the material of the subject.
- FIG. 7A and FIG. 7B show images obtained by polarization imaging using a ceramic cup with a smooth surface and a wooden board having fine irregularities on the surface as subjects.
- the four images in FIG. 7B are diagrams schematically depicting the four images in FIG. 7A.
- the change in the luminance pattern was not observed so much even when the polarization of the polarized illumination was changed.
- the angle ⁇ I of the polarization plane of the polarized illumination is changed, the observed luminance image is greatly increased. It turned out that there was a change. Such a difference is explained as follows.
- FIG. 8 shows a state in which polarized light having an incident angle close to zero is incident on the surface 801 and direct reflection is observed with a camera.
- the polarization planes of incident polarized light are different by 90 °.
- the linearly polarized light of the reflected light has almost the same luminance as the incident light only by changing the traveling direction of the light. This is due to the following reason.
- FIG. 9 is a graph showing the incident angle dependence of the specular reflectance according to Fresnel theory.
- the horizontal axis represents the incident angle
- the vertical axis represents the Fresnel reflectance.
- An incident angle in the vicinity of 0 ° to 15 ° that can be regarded as normal incidence corresponds to a range 901.
- FIG. 10A is a graph showing the luminance fluctuation of the same pixel when a luminance image is taken while changing the polarization plane of light (polarized illumination) incident on the surface of the wooden board.
- FIG. 10B is a luminance image of a wooden board to be imaged (luminance image during non-polarized illumination).
- FIG. 10C is a diagram schematically showing the unevenness of the surface of the wooden board shown in FIG. 10B.
- FIG. 11 shows the variation of the luminance Y in a specific pixel of the luminance image obtained when the angle ⁇ I of the polarization plane of the polarized illumination is 0 °, 45 °, 90 °, and 135 °. From this graph, it can be seen that the luminance Y periodically varies with respect to the angle ⁇ I of the polarization plane of each polarized illumination.
- the surface of the wooden board is not smooth and there are many grooves where incident light is reflected multiple times. Therefore, the luminance Y is considered to vary depending on the polarization angle ⁇ I of the illumination. The reason will be described in detail.
- FIG. 12 shows a state in which a groove 1201 is formed on the surface and multiple reflections are generated twice on the slope.
- This multiple reflection is thought to occur on various natural objects such as cloth, wood, human skin, and skin, such as a subject surface with many irregularities on the surface.
- the nature of the first and second reflections is important, and the third and subsequent multiple reflections have low brightness and can be almost ignored, so only the second reflection is considered.
- 1st time diffuse reflection 2nd time: specular reflection 2nd time: diffuse reflection 2nd time: diffuse reflection 3)
- 1st time: specular reflection 2nd time: 4 of specular reflection A street phenomenon can be assumed.
- the phenomenon of specular reflection can be considered as the main phenomenon in the first and second rounds of 4). If the surface of the groove slope is not completely smooth and the illumination light is not perfectly parallel light, the specular reflection is different from the ideal mirror surface. Therefore, according to experiments, it was confirmed that the two-time reflection can be observed and imaged relatively easily even at a position where the specular reflection condition is not completely satisfied, and that the polarization characteristic is caused by specular reflection.
- FIG. 12A and FIG. 12B each show a part of the groove 1201 present on the surface of the subject. At least a part of the groove 1201 extends in one direction on the subject surface. This extending direction is referred to as “main axis direction”.
- the actual groove 1201 does not need to extend linearly and may extend curvedly. Even a groove extending in a curve can be regarded as a linear groove extending approximately in the principal axis direction.
- V-shaped groove a groove that exists on the surface of a living organ can be referred to as a “V-shaped groove”.
- the cross section of such a V-shaped groove need not be strictly “V-shaped”, and may include a curved surface.
- the following explanation can be applied if a groove having a substantially “V-shaped” cross section exists on the surface of the subject.
- a structure in which a concave portion sandwiched between two adjacent convex surfaces extends in a direction perpendicular to the paper surface as shown in FIG. 22 referred to later is an example of a V-shaped groove.
- the polarized illumination incident perpendicularly to the groove main axis direction 1202 is a P wave.
- the inclination angle of the groove 1201 of the subject is about 45 ° and illumination is incident on the groove 1201 from above, as can be seen from the graph of Fresnel reflectivity, in this incident angle range 902, S Compared with waves, the reflectance of P waves is extremely weak. Furthermore, the P wave becomes weaker while passing through the reflection once and twice. On the other hand, the S-polarized light shown in FIG. 12B does not weaken so much even after two reflections.
- the reflected light becomes extremely weak in terms of energy, and the luminance decreases.
- the incident polarization plane that becomes the S wave the reflected light is not so attenuated in energy and has high brightness.
- the inventor of the present application has found that the function form of the change in the luminance Y obtained by the twice reflection of the polarized illumination in the groove varies substantially the same as when non-polarized light is incident. Hereinafter, this point will be described.
- FIG. 13A is a view of the groove on the surface of the subject viewed from directly above the surface. This corresponds to viewing FIG. 12 from above.
- FIG. 13A shows XY coordinates parallel to the captured image plane.
- the angle formed between the direction perpendicular to the main axis direction 1202 of the groove 1201 and the positive part of the X axis is denoted by ⁇ .
- FIG. 13 (b) shows the angle ⁇ I of the polarization plane of the polarized illumination incident on the subject.
- FIG. 13 (c) shows the contents of FIG. 13 (a) and the contents of FIG. 13 (b) as one.
- the direction of the groove is designated by the angle ⁇ . This differs from the azimuth angle of the main axis of the groove by 90 °.
- the direction of the groove is specified by the angle ⁇ .
- the incident light is reflected twice in the groove as shown in FIG.
- the luminance of linearly polarized light having a polarization plane at a certain angle ⁇ is observed.
- FIG. 14B is a diagram illustrating an angle ⁇ of linearly polarized light at which luminance is observed. If the polarization luminance at the angle ⁇ is I ( ⁇ , ⁇ ), this can be expressed by the following equation.
- the energy reflectances in the groove direction ( ⁇ ) and the principal axis direction ( ⁇ / 2 ⁇ ) are A and B, respectively.
- This polarization luminance I ( ⁇ , ⁇ ) is expressed by the following expression 2 by modifying expression 1. From this equation 2, it can be seen that the polarization luminance I ( ⁇ , ⁇ ) varies with a period ⁇ with respect to ⁇ .
- the incident polarization plane angle is not 0 ° but general ⁇ I.
- the polarization luminance when the incident polarization plane angle is ⁇ I and the observation angle is ⁇ is given by the following equation.
- the polarization luminance shown by this equation is the polarization luminance observed at the observation angle ⁇ in a specific direction, when observing the average luminance of non-polarized light, the polarization luminance shown by equation 3 is 1 for the observation angle ⁇ .
- the sine function and cosine function related to ⁇ become zero. That is, the luminance PY ( ⁇ I, ⁇ ) observed when the polarized light having the incident polarization plane angle ⁇ I is incident on the groove specified by the angle ⁇ and reflected twice is 180 ° with respect to ⁇ I as shown in the following equation. Expressed as a periodic function.
- the degree of modulation of luminance fluctuation can be considered in consideration of the fact that the cosine function term fluctuates from +1 to -1. This ratio is referred to as a luminance modulation degree YD.
- This luminance modulation degree YD is obtained by the following equation.
- the maximum luminance angle YPH and the luminance modulation degree YD are given in units of pixels. Therefore, an image in which the maximum luminance angle YPH is set for each pixel constituting the image is referred to as a “maximum luminance angle image YPH”. Similarly, an image in which the luminance modulation degree YD is set for each pixel constituting the image is referred to as a “luminance modulation degree image YD”.
- the maximum luminance angle YPH and the luminance modulation degree YD are amounts corresponding to the polarization principal axis angle and the polarization degree in normal polarization observation, respectively, but the quantitative relationship is not clear. Therefore, in order to clarify the relationship between the two, the polarization state of twice reflection when non-polarized illumination is incident on the groove is examined.
- FIG. 15 is a diagram when the unpolarized light 1501 is incident on the groove.
- unpolarized light 1501 is incident on a groove having an angle of ⁇
- energy is considered to be evenly distributed in the principal axis direction of the groove and the direction perpendicular thereto, so that energy multiplied by energy reflectivities A and B is used.
- the polarization luminance takes the maximum value (reflectance B) in the groove main axis direction and takes the minimum value (reflectance A) in the vertical direction of the main axis from the explanation in FIG.
- the degree of polarization DOP is calculated, It becomes.
- the maximum luminance angle YPH which is the phase angle of the luminance fluctuation when the angle ⁇ I of the polarization plane in the polarized illumination is rotated, coincides with the polarization main axis in the non-polarized illumination.
- the luminance modulation degree YD which is the amplitude of the luminance fluctuation when the angle ⁇ I of the polarization plane in the polarized illumination is rotated, matches the polarization degree DOP in the non-polarized illumination. Therefore, the discussion of the Fresnel reflection theory and surface normal on the premise of non-polarized illumination can be used for fluctuations in polarization luminance in the present invention.
- the image processor 108 in the present embodiment obtains the above-described maximum luminance angle image YPH and luminance modulation degree image YD, and acquires the surface unevenness information of the subject. Next, a configuration example and operation of the image processor 108 will be described with reference to FIG.
- FIG. 16 is a block diagram showing a configuration of the image processor 108. While changing the incident polarization plane angle ⁇ I of illumination to 0 °, 45 °, 90 °, and 135 °, and illuminating the subject with the polarized light of each incident polarization plane angle ⁇ I, a luminance image group 1601 composed of four luminance images is obtained. To be acquired. The four luminance image groups 1601 thus captured are input to the variable luminance processing unit 160 of the image processor 108.
- the luminance fluctuation when the polarization plane of the polarized illumination is rotated is a cosine function having a period of 180 °.
- the variation luminance processing unit 160 fits luminance variation into a cosine function.
- Y ( ⁇ I) indicating the luminance variation is expressed as follows using the angle ⁇ I of the polarization plane of illumination as a variable.
- a method for estimating the above value by fitting a cosine function from four equally spaced angle samples is as follows.
- the luminance Y ⁇ I _ ave of the original image under non-polarized illumination by the following equation.
- the luminance Y ⁇ I — ave approximately reproduces the luminance image under non-polarized illumination, and can be used as a normal observation image of the endoscope.
- the luminance Y ⁇ I _ ave can be referred to as a "non-polarized average luminance image".
- optimal fitting is performed using the least square error from the sampled luminance to the cosine function.
- it is carried out from samples in four directions of 0 °, 45 °, 90 °, and 135 °. Since the cosine function is determined by three types of information of amplitude, phase, and average value, in order to determine these, any number of samples may be used as long as it is three or more samples. However, in the case of a 45 ° sample, there is a property that the optimum fitting is simplified.
- the phase ⁇ o of the cosine function that minimizes this square error can be obtained from the following equation. From this equation, the solution is given by:
- mathematical functions such as inverse trigonometric functions are subject to the following restrictions.
- the angle taking the minimum value and the angle taking the maximum value can be calculated as follows by performing the case difference from the magnitude relationship between a and c.
- the value of ⁇ 0max that takes this maximum value may be used as the luminance maximum angle image YPH as it is.
- the maximum value and the minimum value of the amplitude is as follows.
- the maximum luminance angle image YPH and the luminance modulation degree image YD are obtained.
- the reference sign “YPH” is attached to the maximum brightness angle image YPH
- the reference sign “YPH” is attached to the brightness modulation degree image YD.
- the luminance maximum angle image YPH is sent to the azimuth angle processing unit 1604, and the luminance modulation degree image YD is sent to the zenith angle processing unit 1606, respectively.
- FIG. 18A is a diagram showing two angles that specify the normal direction of the surface of the subject, that is, an azimuth angle and a zenith angle.
- the normal vector is a three-dimensional vector, but the length is normalized to 1. Therefore, the degree of freedom of the normal vector is 2, and when expressed as an angle, it is expressed by an azimuth angle ⁇ within the screen and a zenith angle ⁇ with respect to the line of sight.
- an XY axis is set in the image, and the direction of the Z axis is the line of sight (optical axis).
- the relationship with the three normal components (Nx, Ny, Nz) is as shown in the figure.
- the azimuth angle processing unit 1604 calculates the azimuth angle ⁇ using the luminance maximum angle image YPH.
- the Fresnel theory regarding specular reflection when non-polarized light is incident is referred to from the above discussion.
- Non-Patent Document 2 non-polarized light is incident and polarized light is observed with a polarizing plate in front of the camera.
- the P wave is attenuated and the S wave is dominant in the reflected light that is specularly reflected from the surface of the subject.
- the azimuth angle ⁇ of the normal line on the groove surface is equal to the angle of the polarization plane that minimizes the luminance.
- the direction determined by this azimuth angle ⁇ matches the direction perpendicular to the plane of polarization where the luminance is maximum.
- the azimuth angle ⁇ of the normal of the groove surface matches the direction perpendicular to the direction of the maximum polarization luminance angle. That is, the azimuth angle ⁇ can be obtained using the maximum brightness angle image YPH.
- this azimuth angle ⁇ has an indefiniteness of 180 °, as introduced in Non-Patent Document 2 as “180 ° ambiguity”. That is, two candidates different by 180 ° are obtained as the azimuth angle ⁇ of the normal line of the groove surface. Here, selecting one of the two candidates is referred to as “indeterminacy processing”.
- 16 uses an unpolarized luminance image 1612 or a luminance modulation degree luminance modulation degree image YD in order to perform indeterminacy processing.
- FIG. 19A shows a luminance image of a groove and a cross-sectional configuration 1902. Since the groove is larger than the size of each pixel, a luminance distribution exists within one groove.
- the groove cross-sectional configuration 1902 has two inclined surfaces, and the inclined angle of the inclined surface is in the range of 30 to 60 °.
- the luminance value becomes high (bright) in the area 1903 indicated by the halftone dots, and the luminance value becomes low (dark) in the area 1913 near the bottom of the groove. That is, the brightness value has a gradient inside the groove.
- Unpolarized light to implement the spatial differentiation processing on the luminance Y ⁇ I _ ave obtained under illumination, calculating the gradient vector of the luminance values, the luminance gradient vectors 1904 and 1905 are obtained.
- the gradient vectors 1904 and 1905 are calculated for each of the two inclined surfaces in the groove.
- the candidate 1906a is adopted at the point A and the candidate 1907a is adopted at the point B. Therefore, the azimuth angle ⁇ of the candidate 1906a indicated by the downward arrow is selected at the point A, and the azimuth angle ⁇ of the candidate 1907a indicated by the upward arrow is correctly obtained at the point B.
- the degree of polarization DOP increases near the bottom of the groove due to reflection twice in the groove.
- the luminance modulation degree value when the polarized illumination is rotated shows the same behavior. Therefore, in the luminance modulation degree image YD, the value (luminance modulation degree) increases in the area 1908 in the vicinity of the groove bottom 1913, and the value decreases outside the groove. Therefore, when the gradient vector of the luminance modulation degree image YD is calculated, luminance modulation degree gradient vectors 1909 and 1910 are calculated.
- the azimuth angle ⁇ obtained from the maximum brightness angle image YPH has an indefiniteness of 180 °
- two candidates 1911a and 1911b are obtained at point A
- two candidates 1912a and 1912b are obtained at point B. Is obtained.
- the candidate 1911a at the point A and the candidate at the point B 1912a is employed.
- the gradient vector calculation part and the normal vector calculation part are drawn so as to be different, but this is for convenience. In actual image processing, the gradient vector is accurately calculated at points A and B where the normal vector is estimated.
- FIG. 19C is a flowchart of the procedure for determining the azimuth angle.
- step S19C01 the candidate ⁇ 1 of the azimuth angle ⁇ of the groove is obtained by rotating the value of the maximum luminance angle image YPH (maximum luminance angle) by 90 °.
- step S19C02 another azimuth angle candidate ⁇ 2 obtained by rotating the candidate ⁇ 1 by 180 ° is obtained.
- step S19C03 the evaluation values ⁇ 1 and ⁇ 2 of the angle difference between the gradient angle obtained from either the luminance gradient or the luminance modulation degree and the candidates ⁇ 1 and ⁇ 2 are calculated.
- the luminance modulation degree image is a feature that can be stably acquired, and if it is devised for polarized illumination as disclosed in the present invention, it can be acquired without any special contrivance on the imaging device side to be observed, so it is highly effective. .
- step S19C04 it is selected whether to use the luminance gradient or the luminance modulation degree gradient.
- the condition of step S19C05 is set, and the one having the larger angular difference is selected from ⁇ 1, ⁇ 2, and ⁇ is determined.
- the condition of step S19C06 is set, and the one having the smaller angle difference is selected from among ⁇ 1 and ⁇ 2, and ⁇ is determined.
- the zenith angle processing unit 1606 calculates the zenith angle ⁇ using the luminance modulation degree image YD.
- the Fresnel theory when non-polarized light is incident is adopted. In this case, as described in Non-Patent Document 2, non-polarized light enters and the polarization is observed with a polarizing plate in front of the camera.
- the degree of polarization DOP of the reflected light that is specularly reflected from the surface of the object is calculated, the relationship between the zenith angle of the surface normal and the Fresnel theory curve using the refractive index NN is established. To do.
- the luminance modulation degree image YD value is used instead of DOP to determine the zenith angle.
- this zenith angle has indefiniteness with a Brewster angle in between.
- FIG. 20A shows the relationship between the incident angle of illumination and the degree of polarization DOP while changing the refractive index NN from 1.5 to 3.0.
- the incident angle is directly the zenith angle of the surface.
- the degree of polarization DOP is calculated from the following Fresnel reflection formula using the refractive index NN of the material when non-polarized incident light is incident on the subject surface at an incident angle ⁇ and is specularly reflected at the same exit angle ⁇ . Is done.
- the above indefiniteness means that when the zenith angle is obtained from the DOP, two angles are estimated across the Brewster angle, which is the angle at which the curve is maximum, and cannot be determined as one.
- FIG. 20B is a diagram illustrating a method for solving the indefiniteness with the Brewster angle interposed therebetween. It is assumed that the groove inclination angle due to the surface mucosa in the living body observed with an endoscope is approximately 55 ° or less, which corresponds to the Brewster angle. The difficulty is solved by limiting the search range from 0 ° to Brewster angle shown in FIG. 20B.
- FIG. 20C is a flowchart for determining the zenith angle.
- step S20C01 the maximum value MINDIF of the polarization degree difference is set, and in step S20C02, the Brewster angle ⁇ B is theoretically obtained from the refractive index NN.
- step S20C03 ⁇ is set to 0 °, and if it is smaller than the Brewster angle in S20C04, the following calculation is performed.
- step S20C05 the theoretical polarization degree DOP shown in (Equation 21) is obtained, and in step S20C06, the difference absolute value DIF between this DOP and the luminance modulation degree YD is calculated. If this DIF is smaller than MINDIF in step S20C07, ⁇ MIN is set to this ⁇ , and DIF is set to MINDIF.
- step S20C09 the angle of ⁇ is increased by 1 ° and the loop process is continued. If this loop process is exited in step S20C04, ⁇ MIN is determined as the zenith angle.
- the normal image generation unit 1608 obtains a normal vector (Nx, Ny, Nz) of the subject surface in the camera coordinate system from the obtained azimuth angle ⁇ and zenith angle ⁇ using (Equation 19), and obtains it in a two-dimensional manner. A normal image.
- the luminance image generation unit 1609 generates a luminance image using a physical reflection model formula by giving a camera viewpoint direction and an illumination light source direction to the obtained normal line image.
- the Cook-Trans model is used as a model formula that well expresses the specular reflection of the subject. According to this, the luminance Is is expressed by the following equation.
- ⁇ in the above equation is an angle formed by the bisected vector H and the normal line N
- ⁇ r is an angle formed by the line-of-sight vector and the normal line N. It is.
- the Fresnel coefficient F and the geometric damping factor G are expressed by the following equations.
- the illumination direction setting unit 1610 is an element for setting the light source vector, and is freely set by a doctor who is an observing user in endoscopic diagnosis or the like.
- Each component shown in FIG. 16 may be realized by special hardware or a combination of hardware and software.
- at least some of the above-described components can be realized by a processor.
- the operation of the image processing unit of the present embodiment can be defined by a computer program stored in the memory of the image processing unit.
- Such a computer program is a set of commands for causing a processor provided in the image processing apparatus to execute various steps (FIGS. 19C and 20C).
- FIG. 21A is a diagram showing the results of the surface normal estimation experiment according to the present embodiment.
- the subject is a lenticular lens plate having a kamaboko-shaped cross section.
- the subject is painted in a red or chocolate color system in order to make specular reflection dominant. The above processing was performed on this subject.
- FIG. 21A shows the non-polarized luminance image 1612 in FIG. 16, and the lower image in FIG. 21A shows the luminance modulation degree image YD in FIG.
- white (high lightness) pixels show high luminance, but in a luminance modulation degree image, dark (low lightness) pixels show high values (modulation degree).
- FIG. 21B is a diagram schematically showing only a part surrounded by the quadrangle of FIG. In the luminance image, a high luminance portion (white portion 2104) corresponding to the convex portion 2101 and a low luminance portion (shaded portion 2103) corresponding to the concave portion 2102 are repeated.
- the luminance modulation degree image a portion with a high luminance modulation degree (halftone portion 2105) and a portion with a low luminance modulation degree (white portion 2106) are repeated.
- the low luminance portion corresponds to a high luminance modulation degree.
- FIG. 22 is a cross-sectional view of the subject (lenticular plate) shown in FIG.
- the lenticular plate has irregularities periodically, and the illumination light is reflected only once at the convex portion 2201 and imaged by the camera.
- the light forming the image of the convex part 2201 is reflected once and has extremely high luminance. Since the recess 2202 forms a groove, the light is reflected twice and captured by the camera. For this reason, the image of the light reflected by the recess 2202 has a slightly low luminance.
- FIG. 23 shows the profiles of luminance and luminance modulation degree in FIG.
- a curve 2301 in the figure represents the luminance
- a curve 2302 represents the luminance modulation degree. It can be seen that the luminance modulation degree is increased in the low luminance portion (the concave portion of the curve 2301).
- FIG. 24 is a plan view showing another subject. This object is obtained by processing and painting eight grooves A to I on a plastic plate.
- FIG. 24A is a diagram showing a photograph showing a luminance image obtained from a real subject
- FIG. 24B is a schematic diagram thereof.
- the azimuth angle interval between the grooves in the plane is 22.5 °.
- the azimuth angle indeterminacy processing unit 1607 and the zenith angle processing unit 1606 in FIG. 16 are implemented for each groove from A to I of the subject in FIG. It is the result of estimating ⁇ .
- the graph with halftone dots shows the correct answer, and the graph with diagonal lines shows the estimation results.
- the correct answer is measured using a laser displacement meter.
- the azimuth angle estimation result of FIG. 25 is estimated with an error of about 10 °.
- the error is slightly large.
- FIG. 27 shows the result of a luminance image obtained by performing all the processes in FIG. 16 on the subject in FIG.
- FIG. 27A is an image when the position of the illumination light source is irradiated from (a) the right side toward the screen, (b) from the left side toward the screen, (c) from the lower side toward the screen, and (d) from the upper side toward the screen, respectively. Is generated.
- FIG. 27B is a schematic diagram, and (a) to (d) correspond as they are. It can be seen that the grooves designated by A to I are clearly expressed by the change of the illumination direction. Therefore, it is possible to provide a clear uneven image with respect to an endoscopic image having only illumination from the front as shown in FIG. 24A.
- the image processing apparatus has substantially the same configuration as that in FIG. 1C, but is different in that a color filter 2801 is added.
- the polarization state observed in the groove varies greatly depending on the color of the subject. That is, according to the narrow band observation near the wavelength of 520 (nm), subjects such as chocolate and red are dark images as a whole, and very strong polarized light can be observed in the groove, whereas in the yellow color, A bright image as a whole can be obtained, but the polarization in the groove becomes very weak. This is presumably because the diffuse reflection component is dominant in bright colors, and the specular reflection of the two-time reflection is almost hidden.
- polarized illumination light that matches the wavelength band where the spectral reflectance of the subject is low is used. For example, in the case of the above yellow, a dark image is photographed using a blue illumination color which is a complementary color.
- the wavelength range of the illumination light is preferably determined in consideration of the spectral reflectance of the subject.
- FIG. 29 is a diagram showing an example of the spectral reflectance of the large intestine mucosa, which is a representative organ in endoscopic observation.
- the colonic mucosa has a strong absorption at 520-600 (nm). Therefore, if the spectral filter characteristics are matched to this low reflectance region to have a characteristic of 2801, it will be photographed as a relatively dark color in this wavelength band, which is suitable for observing surface grooves by polarized light as described in the present invention.
- a filter 2801 is installed at the output stage of the light source 104. Note that the filter 2801 may be used by switching from the case of normal color image observation.
- the color filter may be installed in front of the imaging side 110.
- the image processing apparatus according to the present embodiment is an apparatus applied not only to an endoscope but also to a camera with illumination for medical use such as dermatology and dentistry, a fingerprint imaging apparatus, and a surface inspection apparatus.
- FIG. 30A shows a configuration example of this embodiment.
- the image processing apparatus of this embodiment includes an apparatus 400 instead of the endoscope 101 in FIG. 1C.
- the apparatus 400 includes a ring illumination 4001, a ring-shaped polarization plane control element 4002, a photographing lens 4003, and an image sensor 4004.
- FIG. 30B is a diagram showing an overview of FIG. 30A.
- a ring-shaped polarization plane control element 4002 is installed on the ring illumination 4001.
- Non-polarized light is input to the ring illumination 4001 and the polarization plane control element 4002 from a light guide such as an optical fiber, and the polarization plane of the illumination is set to 0 °, 45 °, 90 °, 135 °, for example, as shown in FIG.
- the ring illumination 4001 may be a self-luminous light source such as an LED that does not use a light guide from the light source. Further, if the angle formed by the imaging optical axis and the optical axis of the illumination light is 15 ° or less, strobe light emission other than ring illumination may be used. By using ring illumination, surface irregularities and grooves can be estimated with high accuracy even in a subject that is difficult to observe with only one illumination.
- the optical axis of the illumination light is substantially the same as the imaging optical axis and is made uniform, so it is suitable for a device surface inspection device for scratches and irregularities, fingerprint imaging devices, dermatological skin roughness imaging devices, etc. is there.
- the image processing processor in the first embodiment can be applied to the imaging element 4004 and an image processing processor (not shown).
- the interval of the rotation angle of the linearly polarized light of illumination is set to 45 °, but this angle does not have to be the same and may be different from each other. Further, the angle interval is not limited to 45 °. However, more than two samples are required to determine the three parameters of the cosine function. That is, it is necessary to change the rotation angle of the linearly polarized light of the illumination to three or more. When there are three types of sample angles, for example, three angles of 0 °, 60 °, and 120 ° can be selected.
- the present invention is a medical endoscope camera, dermatology, dentistry, internal medicine, surgery and other medical use cameras, industrial endoscope cameras, fingerprint imaging devices, surface inspection devices such as surface unevenness observation, inspection,
- the present invention can be widely applied to the field of image processing that requires recognition.
Abstract
Description
図1Cは、本発明の実施形態1における画像処理装置の全体構成を模式的に示す図である。
1)1回目:拡散反射 2回目: 鏡面反射
2)1回目:拡散反射 2回目: 拡散反射
3)1回目:鏡面反射 2回目: 拡散反射
4)1回目:鏡面反射 2回目: 鏡面反射
の4通りの現象が想定できる。
この2乗誤差を最小化する余弦関数の位相Ψoは、以下の式から求められる。
次に、図28を参照しながら、本発明による画像処理装置の第2の実施形態を説明する。
以下、図30Aおよび図30Bを参照しながら、本発明による画像処理装置の第2の実施形態を説明する。本実施形態の画像処理装置は、内視鏡のみならず、皮膚科や歯科などメディカル用途の照明付きカメラ、指紋撮影装置、表面検査装置などへ適用される装置である。
102 制御装置
103 挿入部
104 光源
105 ライトガイド
106 偏光面制御素子
107 照明レンズ
108 画像プロセッサ
109 撮影レンズ
110 撮像素子
111 映像信号線
112 同期装置
113 先端部
120 偏光照明部
140 撮像部
150 画像処理部
160 変動処理部
170 法線推定部
Claims (15)
- 偏光面の角度が異なる3種類以上の直線偏光を、順次、被写体に照射する偏光照明部と、
前記3種類以上の直線偏光の各々によって前記被写体が照射されているときに、順次、前記被写体を撮像し、その際に前記被写体からの戻り光を、偏光子を介さずに受けて輝度値を取得する撮像部と、
前記撮像部から出力される輝度値を示す信号に基づいて、前記偏光面の角度と各画素の輝度値との関係を求め、各画素について前記輝度値が最大となる前記偏光面の角度によって定義される輝度最大角画像、および各画素について前記偏光面の変化にともなう前記輝度値の変動の振幅と輝度平均値との比率によって定義される輝度変調度画像を生成する変動輝度処理部と、
前記輝度最大角画像および前記輝度変調度画像に基づいて、前記被写体の表面に存在するV字グルーブ内の傾斜面の法線を画素単位で推定する法線推定部と、
を備える画像処理装置。 - 前記法線推定部は、
前記輝度最大角画像から前記法線の方位角の候補を求める方位角処理部と、
前記輝度変調度画像から前記法線の天頂角を求める天頂角処理部と、
前記法線の方位角の候補から前記法線の1つの方位角を決定する方位角不定性処理部と、
有している、請求項1に記載の画像処理装置。 - 前記法線推定部によって推定された法線の画像を生成する法線画像生成部を備えている、請求項1または2に記載の画像処理装置。
- 前記方位角不定性処理部は、非偏光照明下での画像に相当する非偏光輝度画像、または前記輝度変調度画像に基づいて、前記法線の方位角の候補から1つを選択する、請求項1から3のいずれかに記載の画像処理装置。
- 前記変動輝度処理部は、前記撮像部によって取得された複数の輝度画像の加算平均を行うことにより、前記非偏光輝度画像を生成し、前記方位角不定性処理部に与える、請求項4に記載の画像処理装置。
- 前記方位角不定性処理部は、前記非偏光輝度画像の空間的な勾配ベクトル、および、前記輝度変調度画像の空間的な勾配ベクトルの少なくとも一方に基づいて、前記法線の方位角の候補から1つを選択する、請求項4または5に記載の画像処理装置。
- 前記偏光照明部および前記撮像部は、内視鏡に取り付けられている請求項1に記載の画像処理装置。
- 前記偏光照明部は、非偏光の光を、偏光面を可変可能な偏光面変換素子を透過させることによって偏光面が3種類以上に順次変化する直線偏光を照射する請求項1から7のいずれかに記載の画像処理装置。
- 前記偏光照明の光軸と前記撮像部の光軸との間の角度は15°以下である請求項1から8のいずれかに記載の画像処理装置。
- 前記撮像部はモノクロ撮像素子またはカラー撮像素子を有している請求項1から9のいずれかに記載の画像処理装置。
- 前記被写体の照明方向を仮想的に自在変化させるための照明方向設定部と、
前記照明方向から照明された状態の前記被写体の輝度画像を前記法線推定部の出力に基づいて生成する輝度画像生成部と、
を備える、請求項1から10のいずれかに記載の画像処理装置。 - 前記偏光照明部は、前記被写体の表面の分光反射率特性が極小になる反射率に相当する波長帯域を透過する分光フィルタを出力段に備える請求項1から11のいずれかに記載の画像処理装置。
- 前記偏光照明部は、
非偏光の光を放射するリング型照明光源と、
前記リング型照明光源から放射された非偏光の光を前記直線偏光に変換するリング型偏光面変換素子であって、前記直線偏光の偏光面の角度を順次変化させることができるリング型偏光面変換素子と、
を備える請求項1から12のいずれかに記載の画像処理装置。 - 偏光面の角度が異なる3種類以上の直線偏光を、順次、被写体に照射するステップと、
前記3種類以上の直線偏光の各々によって前記被写体が照射されているときに、順次、前記被写体を撮像し、その際に前記被写体からの戻り光を、偏光子を介さずに受けて輝度値を取得するステップと、
前記偏光面の角度と各画素の輝度値との関係を求め、各画素について前記輝度値が最大となる前記偏光面の角度によって定義される輝度最大角画像、および各画素について前記偏光面の変化にともなう前記輝度値の変動の振幅と輝度平均値との比率によって定義される輝度変調度画像を生成するステップと、
前記輝度最大角画像および前記輝度変調度画像に基づいて、前記被写体の表面に存在するV字グルーブ内の傾斜面の法線を画素単位で推定するステップと、
を含む画像処理方法。 - 被写体を照射する直線偏光の偏光面の角度が3種類以上異なる複数の偏光画像を受け取り、画像処理により、前記被写体の表面に存在するV字グルーブ内の傾斜面の法線を画素単位で推定する画像処理プロセッサであって、
前記複数の偏光画像から前記偏光面の角度と各画素の輝度値との関係を求め、各画素について前記輝度値が最大となる前記偏光面の角度によって定義される輝度最大角画像、および各画素について前記偏光面の変化にともなう前記輝度値の変動の振幅と輝度平均値との比率によって定義される輝度変調度画像を生成するステップと、
前記輝度最大角画像および前記輝度変調度画像に基づいて、前記被写体の表面に存在するV字グルーブ内の傾斜面の法線を画素単位で推定するステップと、
を実行する画像処理プロセッサ。
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Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2015164518A (ja) * | 2014-02-06 | 2015-09-17 | パナソニックIpマネジメント株式会社 | 画像処理装置 |
JP5857227B2 (ja) * | 2012-11-09 | 2016-02-10 | パナソニックIpマネジメント株式会社 | 画像処理装置および内視鏡 |
WO2016174915A1 (ja) * | 2015-04-30 | 2016-11-03 | ソニー株式会社 | 画像処理装置と画像処理方法およびプログラム |
JP2017058383A (ja) * | 2014-03-04 | 2017-03-23 | パナソニックIpマネジメント株式会社 | 偏光画像処理装置 |
WO2019123625A1 (ja) * | 2017-12-22 | 2019-06-27 | 株式会社ソニー・インタラクティブエンタテインメント | 情報処理装置および表面粗さ取得方法 |
KR20190091734A (ko) * | 2018-01-29 | 2019-08-07 | (주)커넥슨 | 다중 광원 장치 및 복합 필터를 포함하는 휴대용 내시경 및 이를 위한 다중 광원 장치 |
Families Citing this family (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2013054160A1 (en) * | 2011-10-11 | 2013-04-18 | Sony Ericsson Mobile Communications Ab | Light sensitive, low height, and high dynamic range camera |
KR102477190B1 (ko) * | 2015-08-10 | 2022-12-13 | 삼성전자주식회사 | 얼굴 인식 방법 및 장치 |
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Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2009246770A (ja) * | 2008-03-31 | 2009-10-22 | Fujifilm Corp | 撮像装置、撮像方法、およびプログラム |
WO2009157129A1 (ja) * | 2008-06-26 | 2009-12-30 | パナソニック株式会社 | 画像処理装置、画像分割プログラムおよび画像合成方法 |
JP4762369B2 (ja) * | 2009-12-08 | 2011-08-31 | パナソニック株式会社 | 画像処理装置 |
Family Cites Families (12)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPH11313242A (ja) | 1998-04-28 | 1999-11-09 | Nippon Hoso Kyokai <Nhk> | 撮像用光学機器および撮像装置 |
EP1358443A2 (en) * | 2001-01-22 | 2003-11-05 | Jonathan E. Roth | Method and apparatus for polarization-sensitive optical coherence tomography |
US7084910B2 (en) * | 2002-02-08 | 2006-08-01 | Hewlett-Packard Development Company, L.P. | System and method for using multiple images in a digital image capture device |
TW200417236A (en) * | 2003-02-21 | 2004-09-01 | Realtek Semiconductor Corp | Active type digital image capturing device |
JP4974543B2 (ja) | 2005-08-23 | 2012-07-11 | 株式会社フォトニックラティス | 偏光イメージング装置 |
CN101584222B (zh) | 2007-05-31 | 2011-10-12 | 松下电器产业株式会社 | 图像处理装置 |
CN101542232B (zh) | 2007-08-07 | 2011-10-19 | 松下电器产业株式会社 | 法线信息生成装置以及法线信息生成方法 |
US8004675B2 (en) | 2007-09-20 | 2011-08-23 | Boss Nova Technologies, LLC | Method and system for stokes polarization imaging |
JP4486703B2 (ja) | 2007-12-07 | 2010-06-23 | パナソニック株式会社 | 撮像装置 |
JP4435867B2 (ja) * | 2008-06-02 | 2010-03-24 | パナソニック株式会社 | 法線情報を生成する画像処理装置、方法、コンピュータプログラム、および、視点変換画像生成装置 |
WO2010004677A1 (ja) * | 2008-07-08 | 2010-01-14 | パナソニック株式会社 | 画像処理方法、画像処理装置、画像処理プログラム、画像合成方法、および画像合成装置 |
JP2010104424A (ja) * | 2008-10-28 | 2010-05-13 | Fujifilm Corp | 撮像システムおよび撮像方法 |
-
2011
- 2011-07-08 CN CN201180007770.3A patent/CN102742258B/zh active Active
- 2011-07-08 JP JP2012503816A patent/JP4971531B2/ja active Active
- 2011-07-08 WO PCT/JP2011/003931 patent/WO2012011246A1/ja active Application Filing
-
2012
- 2012-04-25 US US13/455,386 patent/US8648902B2/en active Active
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2009246770A (ja) * | 2008-03-31 | 2009-10-22 | Fujifilm Corp | 撮像装置、撮像方法、およびプログラム |
WO2009157129A1 (ja) * | 2008-06-26 | 2009-12-30 | パナソニック株式会社 | 画像処理装置、画像分割プログラムおよび画像合成方法 |
JP4762369B2 (ja) * | 2009-12-08 | 2011-08-31 | パナソニック株式会社 | 画像処理装置 |
Cited By (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP5857227B2 (ja) * | 2012-11-09 | 2016-02-10 | パナソニックIpマネジメント株式会社 | 画像処理装置および内視鏡 |
JPWO2014073138A1 (ja) * | 2012-11-09 | 2016-09-08 | パナソニックIpマネジメント株式会社 | 画像処理装置および内視鏡 |
JP2015164518A (ja) * | 2014-02-06 | 2015-09-17 | パナソニックIpマネジメント株式会社 | 画像処理装置 |
JP2017058383A (ja) * | 2014-03-04 | 2017-03-23 | パナソニックIpマネジメント株式会社 | 偏光画像処理装置 |
US10444617B2 (en) | 2015-04-30 | 2019-10-15 | Sony Corporation | Image processing apparatus and image processing method |
WO2016174915A1 (ja) * | 2015-04-30 | 2016-11-03 | ソニー株式会社 | 画像処理装置と画像処理方法およびプログラム |
JPWO2016174915A1 (ja) * | 2015-04-30 | 2018-02-22 | ソニー株式会社 | 画像処理装置と画像処理方法およびプログラム |
WO2019123625A1 (ja) * | 2017-12-22 | 2019-06-27 | 株式会社ソニー・インタラクティブエンタテインメント | 情報処理装置および表面粗さ取得方法 |
JPWO2019123625A1 (ja) * | 2017-12-22 | 2020-12-03 | 株式会社ソニー・インタラクティブエンタテインメント | 情報処理装置および表面粗さ取得方法 |
JP7039616B2 (ja) | 2017-12-22 | 2022-03-22 | 株式会社ソニー・インタラクティブエンタテインメント | 情報処理装置および表面粗さ取得方法 |
US11327329B2 (en) | 2017-12-22 | 2022-05-10 | Sony Interactive Entertainment Inc. | Information processing apparatus and surface roughness acquisition method |
KR20190091734A (ko) * | 2018-01-29 | 2019-08-07 | (주)커넥슨 | 다중 광원 장치 및 복합 필터를 포함하는 휴대용 내시경 및 이를 위한 다중 광원 장치 |
KR102041236B1 (ko) * | 2018-01-29 | 2019-11-06 | (주)커넥슨 | 다중 광원 장치 및 복합 필터를 포함하는 휴대용 내시경 및 이를 위한 다중 광원 장치 |
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