US3716670A - Comb effect elimination - Google Patents
Comb effect elimination Download PDFInfo
- Publication number
- US3716670A US3716670A US00209981A US3716670DA US3716670A US 3716670 A US3716670 A US 3716670A US 00209981 A US00209981 A US 00209981A US 3716670D A US3716670D A US 3716670DA US 3716670 A US3716670 A US 3716670A
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- US
- United States
- Prior art keywords
- line
- parity
- scan
- field
- lines
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- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
- H04N5/00—Details of television systems
- H04N5/76—Television signal recording
- H04N5/84—Television signal recording using optical recording
Definitions
- the time separation between successive field scans is l/60 second. This time is long enough for an object in a reasonably active scene to move a very noticeable distance, so that the object appears in different positions in the odd lines and in the even lines of the picture, which are presented simultaneously in the viewing of the film.
- the visual effect produced in a very sharp picture is an annoying serration of the moving edge which looks like the teeth of a fine comb. This problem does not exist in pure video applications because of the sequential presentation of the fields in their proper time relationship.
- the comb effect elimination technique of this invention is based on restricting the corrective methods to those portions of the image in which motion is detected.
- the inventive technique involves selecting, first of all, one field of each frame of the video image as the dominant or primary-parity field. The other field then becomes the secondary-parity field and is replaced by information derived from the primary-parity field whenever an image element of a secondary-parity line is inconsistent with the corresponding image element of an adjacent primary-parity line. If the odd field is chosen as the dominant or primary-parity field, the basic principles of the invention may be carried out by simply comparing each even line with an adjacent odd line. If there is a difference between the compared lines, the circuit substitutes an interpolation of the next preceding and following oddline signals for the even-line signal as long as the difference lasts.
- three image parameter comparisons are made instead of just one.
- the first comparison is between the secondary-parity prime line (e.g. an even line) and an adjacent secondary-parity (i.e. even) line.
- the second comparison is between the two primaryparity (i.e. odd) lines adjacent to the prime line.
- the third comparison is between the secondary parity (i.e. even) prime line and an adjacent primary-parity (i.e. odd) line.
- the first and second comparisons must each show identity (otherwise a horizontal interface is present); while the third comparison must show a difference (otherwise no comb is present). Only while all three conditions are true is interpolation of adjacent opposite-parity (i.e. odd) lines substituted for the prime line. Although a single odd line may be substituted for the prime line in the motion areas, an interpolation is preferable because it softens the step effect prone to appear along a diagonal interface.
- the disadvantage of the preferred method is that the comb effect must occur over a minimum of 4 lines before it can be eliminated. However, experience has shown that the comb effect does not become annoyingly noticeable unless it occurs over a substantial number of lines.
- the comb elimination has to be done separately in the luminance channel and in the chroma channel, as the phase relationship of the chroma signal between adjacent lines of the same parity requires a phase inversion of one of the signals in each of the first and second comparison steps.
- FIG. 1 is a scan diagram illustrating the comb effect
- FIG. 2 is a scan diagram illustrating a double-image comb effect
- FIG. 3 is a scan diagram illustrating the comparisons involved in the preferred embodiment of the method of this invention.
- FIG. 4 is a block diagram illustrating an electrical circuit for carrying out the method of this invention.
- FIG. 1 DESCRIPTION OF THE PREFERRED EMBODIMENT
- a black object in the picture is moving from left to right against a white background.
- the object is essentially in the position labeled odd-field image," and it is traced in the picture by the odd scan lines 11, I3, 15, etc.
- the even-field scan reaches the object l/60 second later, the object has moved to the position labeled even-field image
- the comb effect can degenerate into a double image, as illustrated in FIG. 2.
- the basic concept of the invention resides in using interpolation (or any other kind of line substitution) only in those areas of the picture where motion between fields actually occurs. In this manner, the sharpness of the picture is preserved everywhere except at the moving interface itself, where the inherent blur of the motion makes the lack of sharpness rather unnoticeable.
- the basic concept can be carried out by detecting any difference between a secondary-parity prime line being scanned and an adjacent primary-parity line, and substituting for the prime line signal, whenever a difference is detected, a signal derived from one or more primary-parity lines.
- this concept alone does not prevent the loss of sharpness of stationary horizontal edges in the picture because such edges produce the same difference between adjacent lines as the comb effect does.
- FIG. 3 A preferred method of making such a distinction is illus trated in FIG. 3.
- C is the prime line being traced. If a comb is present between the vertical dotdash lines of FIG. 3, the following relationships will be true in the comb area: (1) Line C will be similar to line A (both are black); (2) line D will be similar to line B (both are white); and (3) line C will be dissimilar to line D (C is black and D is white).
- relationship (3) is false: all lines are white. In the object area to the right of the comb area, relationship (3) is also false: all lines are black. If a horizontal edge is present between lines A and C, relationship (I is false; if a horizontal edge is present between lines B and D, relationship (2) is false.
- the circuit of FIG. 4 is designed to substitute a 50-50 mixture of lines B and D for line C when, and only when, all three of the above relationships are true.
- the video signal is continuously presented to input 20, from where it is delayed by one line interval in delay line 22 to produce line A; by one field interval in delay line 24 to produce line B; and by one field interval minus one line interval in delay line 26 to produce line D.
- the undelayed video signal from input 20 produces the prime line C.
- relationship (I) is established by comparing lines A and C in comparator 28. Any difference (regardless of sign) between lines A and C produces a control signal 30 proportional to that difference. Control signal 30 is applied to gate 32 for a purpose hereinafter described. Similarly, the truth of relationship (2) is established by comparator 34, which produces a control signal 36 applied to gate 38.
- comparator 40 which compares lines C and D. Comparator 40 translates any difference (regardless of sign) between lines C and D into a control signal 42 proportional to that difference.
- the control signal 42 is applied to selector 44 for a purpose hereinafter described.
- Gates 32, 38, and selector 44 areadjusted so that they will not be actuated unless their control signals indicate a disparity of sufficient magnitude to cause a visible comb effect in the picture.
- the selector 44 has two inputs from which it can select.
- the upper input in FIG. 4 is the prime line C.
- the lower input is a 50-50 mixture of lines B and D (the two odd lines adjacent to line C) produced by resistors 45,47 fed through clamping amplifiers 49, 51.
- Delay lines 46, 48 are provided to allow time for the control signal 42 to operate selector 44 before the line increment or image element which caused a selection to be made arrives at selector 44.
- Delay line 50 merely compensates for the inherent circuit delays of selector 44 and mixer components 45, 47, 49, 51 so as to assure time coincidence between the two inputs to parity selector 52.
- Control signal 42 is arranged to operate selector 44 to select its lower input, i.e. the combination of lines B and D, for transmission to selector 52.
- selector 44 selects its upper input, i.e., line C, for transmission to selector 52.
- control signals 30 and 36 are absent. In that condition, gates 32 and 38 are conductive and permit the unhindered passage of control signal 42 when it appears. If, however, either relationship (I) or (2) is false, gate 32 or 38 is actuated by control signal 30 or 36 to block control signal 42 from reaching selector 44. In this manner, the combination of lines B and D is substituted for the prime line C when, and only when, relationships (I), (2) and (3) are all true, and the presence of a comb is thus determined.
- parity selector S2 is operated by the scan circuits S4 to select its upper input (i.e., always line C) during odd-field scans, and its lower input (i.e., the combination of lines B and D in comb areas, and line C elsewhere) during even-field scans.
- the net effect of the circuitry of FIG. 4 is that the video signal appearing at output 56 is essentially equal in sharpness to the video signal at input 20, but with the combs removed.
- the only disturbance remaining in the picture at output 56 is a slight blur at each end of a horizontally moving vertical interface, but due to the motion of the interface, this slight blur is not visually noticeable even on a large-screen display.
- a method for eliminating the comb effect in interlaced-scan video pictures recorded on motion picture film comprising the steps of:
- a method for eliminating the comb effect in interlaced-scan video pictures recorded on motion picture film comprising the steps of:
- a comb effect elimination circuit comprising:
- first, second and third delay means for delaying said video signals by one line interval, one field interval, and one field interval minus one line interval, respectively;
- first comparator means for comparing said video signals and the output of said first delay means, and for producing a first control signal in response to a difference therebetween;
- second comparator means for comparing the outputs of said second and third delay means, and for producing a second control signal in response to a difference therebetween;
- third comparator means for comparing said video signal and the output of said third delay means, and for producing a third control signal in response to a difference therebetween; output means; and
- selector means operatively responsive to said control signals for selectively conveying to said output means said video signal or a signal derived from the output of at least one of said second and third delay means.
- circuit of claim 5 further comprising gate means responsive to the presence of said first and second control signals, respectively, to block transmission of said third control signal to said selector means.
- circuit of claim 4 further comprising additional selector means arranged to convey to said output means said video signal during the scan of a field of one parity, and the output of said first-named selector means during the scan of a field of the opposite parity.
Abstract
Description
Claims (8)
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US20998171A | 1971-12-20 | 1971-12-20 |
Publications (1)
Publication Number | Publication Date |
---|---|
US3716670A true US3716670A (en) | 1973-02-13 |
Family
ID=22781129
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US00209981A Expired - Lifetime US3716670A (en) | 1971-12-20 | 1971-12-20 | Comb effect elimination |
Country Status (8)
Country | Link |
---|---|
US (1) | US3716670A (en) |
JP (1) | JPS4871127A (en) |
CA (1) | CA956724A (en) |
DE (1) | DE2261228C2 (en) |
FR (1) | FR2169829B1 (en) |
GB (1) | GB1349443A (en) |
NL (1) | NL7217375A (en) |
SU (1) | SU544396A3 (en) |
Cited By (10)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4096530A (en) * | 1976-06-17 | 1978-06-20 | General Electric Company | Method and apparatus for obscuring the raster lines in a photograph of a video monitor screen |
US4175272A (en) * | 1977-08-30 | 1979-11-20 | Sony Corporation | Video signal processing circuitry for compensating different average levels |
US4361853A (en) * | 1977-04-14 | 1982-11-30 | Telediffusion De France | System for reducing the visibility of the noise in television pictures |
US4388729A (en) * | 1973-03-23 | 1983-06-14 | Dolby Laboratories, Inc. | Systems for reducing noise in video signals using amplitude averaging of undelayed and time delayed signals |
US4845557A (en) * | 1988-05-02 | 1989-07-04 | Dubner Computer Systems, Inc. | Field motion suppression in interlaced video displays |
US5191416A (en) * | 1991-01-04 | 1993-03-02 | The Post Group Inc. | Video signal processing system |
US5313281A (en) * | 1992-09-29 | 1994-05-17 | Sony United Kingdom Ltd. | Video to film conversion |
US5923784A (en) * | 1993-12-02 | 1999-07-13 | General Instrument Corporation | Analyzer and methods for detecting and processing video data types in a video data stream |
US20060215057A1 (en) * | 2005-03-09 | 2006-09-28 | Sony Corporation | Image processing apparatus and method |
US20090190030A1 (en) * | 2008-01-30 | 2009-07-30 | Zoran Corporation | Video signal motion detection |
Family Cites Families (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3502805A (en) * | 1966-04-23 | 1970-03-24 | Int Standard Electric Corp | Method and apparatus for enhancing the suppressed dot structure of television pictures |
DE1271158B (en) * | 1966-04-23 | 1968-06-27 | Standard Elektrik Lorenz Ag | Method for suppressing the point structure during the transmission and / or reproduction of partial television pictures |
FR1528714A (en) * | 1966-04-23 | 1968-06-14 | Int Standard Electric Corp | Method of removing dot structure during transmission and reproduction of television pictures |
-
1971
- 1971-12-20 US US00209981A patent/US3716670A/en not_active Expired - Lifetime
-
1972
- 1972-12-14 DE DE2261228A patent/DE2261228C2/en not_active Expired
- 1972-12-19 SU SU1868339A patent/SU544396A3/en active
- 1972-12-19 CA CA159,381A patent/CA956724A/en not_active Expired
- 1972-12-19 FR FR7245220A patent/FR2169829B1/fr not_active Expired
- 1972-12-19 GB GB5854672A patent/GB1349443A/en not_active Expired
- 1972-12-20 JP JP47128089A patent/JPS4871127A/ja active Pending
- 1972-12-20 NL NL7217375A patent/NL7217375A/xx not_active Application Discontinuation
Cited By (14)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4388729A (en) * | 1973-03-23 | 1983-06-14 | Dolby Laboratories, Inc. | Systems for reducing noise in video signals using amplitude averaging of undelayed and time delayed signals |
US4096530A (en) * | 1976-06-17 | 1978-06-20 | General Electric Company | Method and apparatus for obscuring the raster lines in a photograph of a video monitor screen |
US4361853A (en) * | 1977-04-14 | 1982-11-30 | Telediffusion De France | System for reducing the visibility of the noise in television pictures |
US4175272A (en) * | 1977-08-30 | 1979-11-20 | Sony Corporation | Video signal processing circuitry for compensating different average levels |
US4845557A (en) * | 1988-05-02 | 1989-07-04 | Dubner Computer Systems, Inc. | Field motion suppression in interlaced video displays |
US5191416A (en) * | 1991-01-04 | 1993-03-02 | The Post Group Inc. | Video signal processing system |
US5313281A (en) * | 1992-09-29 | 1994-05-17 | Sony United Kingdom Ltd. | Video to film conversion |
US5923784A (en) * | 1993-12-02 | 1999-07-13 | General Instrument Corporation | Analyzer and methods for detecting and processing video data types in a video data stream |
US6031927A (en) * | 1993-12-02 | 2000-02-29 | General Instrument Corporation | Analyzer and methods for detecting and processing video data types in a video data stream |
US6041142A (en) * | 1993-12-02 | 2000-03-21 | General Instrument Corporation | Analyzer and methods for detecting and processing video data types in a video data stream |
US20060215057A1 (en) * | 2005-03-09 | 2006-09-28 | Sony Corporation | Image processing apparatus and method |
US7612827B2 (en) * | 2005-03-09 | 2009-11-03 | Sony Corporation | Image processing apparatus and method |
US20090190030A1 (en) * | 2008-01-30 | 2009-07-30 | Zoran Corporation | Video signal motion detection |
US8593572B2 (en) | 2008-01-30 | 2013-11-26 | Csr Technology Inc. | Video signal motion detection |
Also Published As
Publication number | Publication date |
---|---|
FR2169829B1 (en) | 1976-04-23 |
DE2261228C2 (en) | 1982-05-06 |
SU544396A3 (en) | 1977-01-25 |
CA956724A (en) | 1974-10-22 |
DE2261228A1 (en) | 1973-07-12 |
GB1349443A (en) | 1974-04-03 |
NL7217375A (en) | 1973-06-22 |
JPS4871127A (en) | 1973-09-26 |
FR2169829A1 (en) | 1973-09-14 |
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Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: SECURITY PACIFIC BUSINESS CREDIT INC., A DE CORP. Free format text: SECURITY INTEREST;ASSIGNOR:IMAGE TRANSFORM, INC.;REEL/FRAME:004874/0001 Effective date: 19880429 |
|
AS | Assignment |
Owner name: DIGITAL LASER TRANSFORM LIMITED Free format text: ASSIGNMENT OF ASSIGNORS INTEREST. EFFECTIVE JUNE 12, 1979;ASSIGNOR:GORMELY INVESTMENTS LIMITED (SUCCESSOR BY AMALGAMATION DATED JANUARY 28, 1982 TO ELLANIN INVESTMENTS LIMITED);REEL/FRAME:004914/0740 Effective date: 19880504 Owner name: COMPACT VIDEO, INC. Free format text: MERGER;ASSIGNORS:COMPACT VIDEO, INC., A CORP OF CA (INTO);COMPACT VIDEO DELAWARE, INC., A DE CORP.;REEL/FRAME:004912/0049 Effective date: 19850513 Owner name: COMPACT VIDEO DELAWARE, INC., A DE CORP. Free format text: MERGER;ASSIGNOR:COMPACT VIDEO, INC.,;REEL/FRAME:004919/0420 Effective date: 19850513 Owner name: IMAGE TRANSFORM, INC., A CA CORP. Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:COMPACT VIDEO, INC., A DE CORP.;REEL/FRAME:004914/0763 Effective date: 19880118 Owner name: COMPACT VIDEO, INC. Free format text: CHANGE OF NAME;ASSIGNOR:COMPACT VIDEO SYSTEMS, INC.;REEL/FRAME:004914/0757 Effective date: 19871215 Owner name: COMPACT VIDEO SYSTEMS, INC. Free format text: ASSIGNMENT OF ASSIGNORS INTEREST.;ASSIGNOR:DIGITAL LASER TRANSFORM LIMITED;REEL/FRAME:004914/0741 Effective date: 19790613 |