Patent US6529616B1 successfully refreshed from Google Patents.
US6529616B1
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US
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Technique for accurate color-color registration measurements
Assignee: Xerox Corp
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Filing: 1999-11-29
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Granted: 2003-03-04
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Expires: 2019-11-29
Abstract
Abstract A special test pattern and image quality analysis system and process for evaluating the test pattern are provided to accurately measure color-color registration in an image output device that prints in CMYK color. The process is robust even when using relatively low-resolution CCD-based scanners and also is unique in that the process automatically factors out errors originating from skew between the detector and the subject of measurement. Further, registration of each of C, M, and Y relative to K are independently determined. The test pattern includes an upper part and a lower part, with both the upper and lower parts having a black K component and the upper part also including color components for C, M and Y. The system and method have potential for being built in to color printers or copiers to allow measurement of color misregistration within the paper path and automatically correct for color registration errors.
Inventors
- 👤 D. Rene Rasmussen
- 👤 Edul N. Dalal
- 👤 Susan June Zoltner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 18:26
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/00002; H04N1/00007; H04N1/00015; H04N1/00023; H04N1/00026; H04N1/00031; H04N1/00045; H04N1/00053; H04N1/00058; H04N1/00061; H04N1/00068; H04N1/00071; H04N1/00074; H04N1/00079; H04N1/46; H04N1/56; H04N1/60; H04N1/603; H04N1/6033
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
258 words
A method of performing image quality analysis on a color image output device having an output station that generates a hardcopy color image output from an input image, the method comprising: providing a test pattern having first and second sections of spaced geometrical marks, the first section of marks being black while the second section includes black marks and at least one color mark of a color other than black; generating a hardcopy image output from the image output device using the test pattern as an input image; scanning the hardcopy image to form a digital raster image using a scanner; and performing image quality analysis on the digital raster image, including determination of color-color misregistration with skew correction, wherein the step of performing image quality analysis includes: taking reflectance profiles across both the first section and the second section using a channel of the scanner complementary to the color other than black; calculating centroids of lines having the color and black; measuring a first offset between a centroid of a color line and a centroid of a corresponding line from the first section having black marks to determine a total misregistration; measuring a second offset between a centroid of a black mark from the second section and a centroid of a corresponding black mark from the first section having black marks to determine the contribution from skew to the previously calculated misregistration; and subtracting the second offset from the first offset to determine color misregistration compensated for skew of the color other than black relative to black.
Claim 2
Independent Claim
258 words
A method of performing image quality analysis on a color image output device having an output station that generates a hardcopy color image output from an input image, the method comprising: providing a test pattern having first and second sections of spaced geometrical marks, the first section of marks being black while the second section includes black marks and at least one color mark of a color other than black; generating a hardcopy image output from the image output device using the test pattern as an input image; scanning the hardcopy image to form a digital raster image using a scanner; and performing image quality analysis on the digital raster image, including determination of color-color misregistration with skew correction, wherein the step of performing image quality analysis includes: taking reflectance profiles across both the first section and the second section using a channel of the scanner complementary to the color other than black; calculating centroids of lines having the color and black; measuring a first offset between a centroid of a color line and a centroid of a corresponding line from the first section having black marks to determine a total misregistration; measuring a second offset between a centroid of a black mark from the second section and a centroid of a corresponding black mark from the first section having black marks to determine the contribution from skew to the previously calculated misregistration; and subtracting the second offset from the first offset to determine color misregistration compensated for skew of the color other than black relative to black.
Claim 3
Dependent Claim
13 words
The method of claim 1 , wherein the geometric marks are parallel lines.
Claim 4
Dependent Claim
15 words
The method of claim 2 , wherein the step of scanning uses an RGB scanner.
Claim 5
Dependent Claim
11 words
The method of claim 1 , wherein the color is cyan.
Claim 6
Dependent Claim
129 words
The method of claim 4 , wherein the step of performing image quality analysis further includes: taking reflectance profiles across both the first section and the second section using a channel of the scanner complementary to magenta; calculating centroids of marks having magenta and black; measuring a first offset between a centroid of a magenta mark and a centroid of a corresponding mark from the one section having black marks to determine a total misregistration; measuring a second offset between a centroid of a black mark from the second section and a centroid of a corresponding black mark from the first section having black marks to determine misregistration due to skew; and subtracting the second offset from the first offset to determine magenta to black misregistration compensated for skew.
Claim 7
Dependent Claim
129 words
The method of claim 4 , wherein the step of performing image quality analysis further includes: taking reflectance profiles across both the first section and the second section using a channel of the scanner complementary to yellow; calculating centroids of marks having yellow and black; measuring a first offset between a centroid of a yellow mark and a centroid of a corresponding mark from the first section having black marks to determine a total misregistration; measuring a second offset between a centroid of a black mark from the second section and a centroid of a corresponding black mark from the first section having black marks to determine misregistration due to skew; and subtracting the second offset from the first offset to determine yellow to black misregistration compensated for skew.
Claim 8
Dependent Claim
42 words
The method of claim 1 , wherein the geometric marks are parallel lines, the step of calculating centroids includes: determining an approximate edge position for a line; defining a line surround; calculating a weight profile; and calculating a centroid of the line.
Claim 9
Dependent Claim
270 words
The method of claim 1 , wherein the geometric marks are parallel lines and the test pattern includes 10 black lines L 1 to L 10 in the first section and 10 lines U 1 to U 10 in the second section, with U 1 and U 2 being black lines, U 3 and U 4 being cyan lines, U 5 and U 6 being magenta lines, U 7 and U 8 being yellow lines and U 9 and U 10 being black lines, the method comprising the steps of: taking reflectance profiles across both the first section and the second section using a channel of the scanner complementary to cyan; calculating centroids of lines U 1 , U 2 , U 3 , U 4 , U 9 and U 10 as XU 1 , XU 2 , XU 3 , XU 4 , XU 9 and XU 10 , respectively; calculating centroids of lines L 1 , L 2 , L 3 , L 4 , L 9 and L 10 as XL 1 , XL 2 , XL 3 , XL 4 , XL 9 and XL 10 , respectively; obtaining a measurement of misregistration UMC uncorrected for skew using the following equation, UMC= 0.5×(( XU 3 + XU 4 )−( XL 3 + XL 4 )); obtaining a measurement of skew SM using the following equation, SM= 0.25×(( XU 1 + XU 2 + XU 9 + XU 10 )−( XL 1 + XL 2 + XL 9 + XL 10 )); obtaining a measurement of cyan to black misregistration MC using the following equation, MC=UMC−SM.
Claim 10
Dependent Claim
24 words
The method of claim 1 , wherein only a central region CR of the first and second sections are used for image quality analysis.
Claim 11
Dependent Claim
19 words
The method of claim 1 , wherein the test pattern is stored in memory in the image output device.
Claim 12
Dependent Claim
14 words
The method of claim 10 , wherein the image output device is a printer.
Claim 13
Dependent Claim
14 words
The method of claim 10 , wherein the image output device is a copier.
Claim 14
Dependent Claim
195 words
An image quality analysis system for performing image quality analysis on a color image output device having an output station that generates a hardcopy color image output from an input image, the system comprising: a test pattern having first and second sections of spaced geometrical marks, the first section of marks being black while the second section includes black marks and at least one color mark; a scanner that forms a digital raster image from a hardcopy image output from an image output device to be tested that used the test pattern as an input image; an image quality analysis module that performs image quality analysis on the digital raster image to determine color-color misregistration corrected for skew, wherein the geometric marks are lines, and the test pattern includes 10 black lines L 1 to L 10 in the first section and 10 lines U 1 to U 10 in the second section, with U 1 and U 2 being black lines, U 3 and U 4 being cyan lines, U 5 and U 6 being magenta lines, U 7 and U 8 being yellow lines and U 9 and U 10 being black lines.
Claim 15
Dependent Claim
195 words
An image quality analysis system for performing image quality analysis on a color image output device having an output station that generates a hardcopy color image output from an input image, the system comprising: a test pattern having first and second sections of spaced geometrical marks, the first section of marks being black while the second section includes black marks and at least one color mark; a scanner that forms a digital raster image from a hardcopy image output from an image output device to be tested that used the test pattern as an input image; an image quality analysis module that performs image quality analysis on the digital raster image to determine color-color misregistration corrected for skew, wherein the geometric marks are lines, and the test pattern includes 10 black lines L 1 to L 10 in the first section and 10 lines U 1 to U 10 in the second section, with U 1 and U 2 being black lines, U 3 and U 4 being cyan lines, U 5 and U 6 being magenta lines, U 7 and U 8 being yellow lines and U 9 and U 10 being black lines.
Claim 16
Dependent Claim
13 words
The system of claim 13 , wherein the geometric marks are parallel lines.
Claim 17
Dependent Claim
13 words
The system of claim 13 , wherein the scanner is an RGB scanner.
Claim 18
Dependent Claim
32 words
The system of claim 15 , wherein the image quality analysis module isolates misregistration for each color by conducting image quality analysis using signals from individual RGB channels of the RGB scanner.
Claim 19
Dependent Claim
16 words
The system of claim 13 , wherein the scanner is integral with the image output device.
Claim 20
Dependent Claim
16 words
The system of claim 13 , wherein the scanner is separate from the image output device.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2006-03-03 | 2006-09-02 | 2007-03-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2010-03-03 | 2010-09-02 | 2011-03-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2014-03-03 | 2014-09-02 | 2015-03-04 | $7700.00 | Window Closed / Lapsed |