Architecture for color space transformation to compensate for relative chip-to-chip spectral variations on a butted full-width array sensor bar

• US 6,266,438 B1
• Filed: 09/28/1998
• Issued: 07/24/2001
• Est. Priority Date: 09/28/1998
• Status: Expired due to Term

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Williams-Fuller, Dawn M., Metcalfe, David J., Taillie, Joseph P., Jedlicka, Josef E.
• Primary Examiner(s): Mancuso, Joseph
• Assistant Examiner(s): Bayat, Ali
• Application Number:
  US09/162,097
• Time in Patent Office: 1,030 Days
• Field of Search: 382/162-167, 438/68, 250/239-208, 250/559.1, 250/559.39, 156/160-297, 156/562, 358/1.9, 358/518, 358/520, 358/523
• US Class Current: 382/162
• CPC Class Codes: H01L 27/14601 Structural or functional details thereof
• CPC Class Codes: H04N 1/56 Processing of colour picture signals H04N1/52 takes precedence
• CPC Class Codes: H04N 1/603 controlled by characteristics of the picture signal generator or the picture reproducer

Abstract

A color space transformation device includes a sensor bar. The sensor bar includes a plurality of sensor chips. Each sensor chip scans a unique section of an original image to produce first data in a first color space. A memory means stores groups of coefficients. Each group of coefficients corresponds to one of the sensor chips. A processor independently transforms each of the sections of the first data to a respective section of a second data. The transformation is performed as a function of one of the groups of coefficients corresponding to the sensor chip which produced the first data.

Claims

1. A system for transforming first data representing an original image in a first color space to second data representing the image in a second color space, comprising:

a plurality of sensors for scanning pixels in the original image and producing the first data, each sensor scanning a plurality of colors associated with the pixels in a respective one of a plurality of portions included in the original image and producing a corresponding portion of the first data, at least two of the sensors including different spectral characteristics;

a memory for storing a plurality of sets of coefficients, each of the sets of coefficients corresponding to one of the sensors; and

a converter for transforming the first data to the second data as a function of the respective set of coefficients corresponding to the sensor for the respective portion of the original image.

2. The system for transforming as set forth in claim 1, wherein the plurality of sensors are butted against one another to form a full-width array sensor bar.

3. The system for transforming as set forth in claim 2, wherein the plurality of sensors are color sensors.

4. The system for transforming as set forth in claim 3, wherein the original image is an original color image.

5. The system for transforming as set forth in claim 2, further including:

a multiplexer for dynamically switching the set of the coefficients corresponding to the respective sensor into the converter.

6. The system for transforming as set forth in claim 5, wherein the converter transforms one portion of the first data during each of a plurality of steps, further including:

means for identifying the sensor corresponding to the portion of the first data being transformed during the respective step.

7. The system for transforming as set forth in claim 6, wherein the sensor chip storage memory is a random access storage memory.

8. The system for transforming as set forth in claim 1, further including:

means for storing the second data.

9. The system for transforming as set forth in claim 8, further including:

a second converter for transforming the second data into a color space compatible with a color printing device; and

a color printer for producing the transformed second data.

10. A method of transforming source data representing an image in a first color space to target data representing the image in a second color space, comprising:

storing a plurality of groups of predetermined coefficients in an accessible memory, each of the groups of the predetermined coefficients corresponding to one of a plurality of chips in a sensor array;

scanning pixels within the image with the chips to acquire a plurality of source data segments, each of the chips scanning a plurality of colors and being associated with a respective one of a plurality of portions of the image, each of the source data segments being stored in one of the chips in the sensor array;

reading one segment of the source data from one of the chips in the sensor array into a transformer;

determining the one chip in the sensor array with which the one segment of the source data is associated;

transferring one of the groups of the predetermined coefficients, which corresponds to the one chip, to the transformer; and

transforming the segment of the source data from the first color space to a segment of the target data as a function of the one group of predetermined coefficients and the chip, the segment of the target data representing the segment of the source data in the second color space.

11. The method of transforming data according to claim 10, further including:

storing the segment of the target data in a second memory.

12. The method of transforming data according to claim 10, the step of scanning including:

scanning an entire line of the image to acquire the plurality of source data segments.

13. The method of transforming data according to claim 10, further including:

repeating the steps of reading, determining, transferring, and transforming for each of the other source data segments in the scanned line.

14. The method of transforming data according to claim 10, wherein the step of transforming includes:

transforming the source data from an RGB color space to a L*a*b* color space.

15. The method of transforming data according to claim 14, wherein the step of transforming includes:

transforming the source data from an RGB color space to a L*a*b* color space via an XYZ color space.

16. The method of transforming data according to claim 10, wherein the step of transferring includes:

passing one of the groups of the predetermined coefficients, which corresponds to the one chip, to the transformer via a multiplexer.

17. The method of transforming data according to claim 10, wherein each of the source data segments corresponds to one pixel in the image, the step of determining including:

counting pixels in the image which have been transformed; and

counting chips for which all the corresponding pixels in the image have been transformed.

18. A color space transformation device, comprising:

a sensor bar including a plurality of sensor chips, each sensor chip being capable of scanning a plurality of colors associated with a respective one of a plurality of unique sections of an original image to produce respective first data in a first color space;

a memory means for storing groups of coefficients, each group of coefficients corresponding to one of the sensor chips; and

a processor for independently transforming one of the sections of the first data to a respective section of a second data, the transformation being performed as a function of one of the groups of coefficients corresponding to the section and the sensor chip which produced the first data.

19. The color space transformation device according to claim 18, further including:

a multiplexer connected to the memory means and the processor for transferring the one group of coefficients, corresponding to the sensor chip which produced the first data, from the memory means to the processor.

20. The color space transformation device according to claim 18, wherein each section of the original image includes a plurality of pixels, the color space transformation device transforming individual and sequential pixels of each section of the original image during a plurality of respective steps, further including:

a pixel counter for counting a number of transformed pixels within each sensor chip; and

a chip counter for counting a number of sensor chips which have had all pixels transformed, the one group of coefficients being identified as a function of values produced by the pixel counter and the chip counter.