IMAGE OUTPUT COLOR MANAGEMENT SYSTEM AND METHOD

• US 20090161127A1
• Filed: 12/20/2007
• Published: 06/25/2009
• Est. Priority Date: 12/20/2007
• Status: Active Grant

• Current Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Original Assignee: Xerox Corporation (Xerox Holdings Corp.)
• Inventors: Mestha, Lalit Keshav, Schweid, Stuart Alan
• Granted Patent: US 7,847,976 B2
• Time in Patent Office: Days
• US Class Current: 358/1.900
• CPC Class Codes: H04N 1/6033 using test pattern analysis H04N1/6055 takes precedence

Abstract

Disclosed is an image output device color management system. The color management system includes a 2 dimensional principle component analysis (PCA) compensation method for reducing the number of measurement required for re-profiling a device, such as a printer.

Claims

1. A method for controlling an image output device comprising:

(a) generating an initial image output device LUT (look-up-table) characterizing an image output device for a plurality of states associated with the image output device, wherein each state of the image output device LUT associates a first set of target colors with a plurality of respective spectral measurements;

(b) generating a first data matrix representing all spectral measurements associated with each respective target color for all image output device states;

(c) calculating the nominal spectral response associated with each target color;

(d) generating a second data matrix representing the target color spectral variation by subtracting the nominal spectral response from each target color spectral response for each state;

(e) performing a first PCA (Principle Component Analysis) on the second data matrix to represent the image output device LUT with a third data matrix including the first set of target colors associated with a predetermined number of spectral directions;

(f) performing a second PCA on each spectral direction associated with the third data matrix to represent the image output device LUT with a fourth data matrix including each principle spectral direction associated with the variation of the first set of target colors;

(g) measuring the spectral properties associated with a second set of target colors, the second set of target colors including a subset first set of target colors; and

(h) estimating an image output device LUT for the first set of target colors utilizing the third and fourth data matrixes, and the measured spectral properties associated with the second set of target colors.

2. The method for controlling an image output device according to claim 1, wherein the first data matrix is represented as D, and the first PCA generates eigenvalues and eigenvectors of D^T D/(M*N), where M equals the number of colors in the first set of target colors and N equals the number of states, and D^T represents the transpose of matrix D.

3. The method for controlling an image output device according to claim 2, wherein M is greater than or equal to 100 and N is greater than or equal to 8.

4. The method for controlling an image output device according to claim 1, wherein the initial image output device LUT is a multi-dimensional profile LUT and step (h) estimates a multi-dimensional image output device profile LUT.

5. The method for controlling an image output device according to claim 1, wherein the initial image output device profile is a single dimensional LUT and step (h) estimates a single dimensional image output device profile LUT.

6. The method for controlling an image output device according to claim 2, wherein the third data matrix (D₃) is calculated according to D₃=D β

r, where r=[β

₁ β

₂ β

₃], where λ

=eigenvalues of D^T D/(M*N), λ

_i represents the i^th largest eigenvalue of D^T D, β

=the eigenvectors of D^T D/(M*N), and β

₁ represents the eigenvector associated with λ

_i.

7. The method for controlling an image output device according to claim 6, wherein the fourth data matrix Data set estimate=patch mean values+c₁₁*β

11_patch*⊕

1_spectral^T+c₁₂*β

12_patch*⊕

1_spectral^T+c₁₃*β

13_patch*β

1_spectral^T+c₂₁*β

21_patch*β

2_spectral^T+c₂₂*β

22_patch*β

2_spectral^T+c₃₁*β

31_patch*β

3_spectral^T, where β

XY_patch is the Y^th eigenvector/principal component of the X^th spectral component and c_xy=β

xy_patch^T*D*β

x_spectral.

8. An image output device color control system comprising:

an image output device comprising an input configured to receive image data for display or printing by the image output device;

a spectral measurement device; and

a controller operatively connected to the image output device and spectral measurement device, the controller configured to receive CMYK or RGB data and convert to image output device independent image input data and map the device independent input data to image output device dependent input data for display or printing by the image output device, wherein the controller comprises a controller-usable data carrier storing instructions that, when executed by the controller cause the controller to perform a method comprising;

(a) generating an initial image output device LUT (look-up-table) characterizing an image output device for a plurality of states associated with the image output device, wherein each state of the image output device LUT associates a first set of target colors with a plurality of respective spectral measurements;

(b) generating a first data matrix representing all spectral measurements associated with each respective target color for all image output device states;

(c) calculating the nominal spectral response associated with each target color;

(d) generating a second data matrix representing the target color spectral variation by subtracting the nominal spectral response from each target color spectral response for each state;

(e) performing a first PCA (Principle Component Analysis) on the second data matrix to represent the image output device LUT with a third data matrix including the first set of target colors associated with a predetermined number of spectral directions;

(f) performing a second PCA on each spectral direction associated with the third data matrix to represent the image output device LUT with a fourth data matrix including each principle spectral direction associated with the variation of the first set of target colors;

(g) measuring the spectral properties associated with a second set of target colors, the second set of target colors including a subset first set of target colors; and

(h) estimating an image output device LUT for the first set of target colors utilizing the third and fourth data matrixes, and the measured spectral properties associated with the second set of target colors.

9. The image output device color control system according to claim 8, wherein the first data matrix is represented as D, and the first PCA generates eigenvalues and eigenvectors of D^T D/(M*N), where M equals the number of colors in the first set of target colors and N equals the number of states, and D^T represents the transpose of matrix D.

10. The image output device color control system according to claim 9, wherein M is greater than or equal to 100 and N is greater than or equal to 8.

11. The image output device color control system according to claim 8, wherein the initial image output device LUT is a multi-dimensional profile LUT and step (h) estimates a multi-dimensional image output device profile LUT.

12. The image output device color control system according to claim 8, wherein the initial image output device profile is a single dimensional LUT and step (h) estimates a single dimensional image output device profile LUT.

13. The image output device color control system according to claim 9, wherein the third data matrix (D₃) is calculated according to D₃=D β

r, where β

_r=[β

₁ β

₂ β

₃], where λ

=eigenvalues of D^T D/(M*N), λ

_i represents the i^th largest eigenvalue of D^T D, β

=the eigenvectors of D^T D/(M*N), and β

₁ represents the eigenvector associated with λ

_i.

14. The image output device color control system according to claim 13, wherein the fourth data matrix Data set estimate=patch mean values+c₁₁*β

11_patch*β

1_spectral^T+c₁₂*β

12_patch*β

1_spectral^T+c₁₃*β

13_patch*β

1_spectral^T+c₂₁*β

21_patch*β

2_spectral^T+c₂₂*β

22_patch*β

2_spectral^T+c₃₁*β

31_patch*β

3_spectral^T, where β

XY_patch is the Y^th eigenvector/principal component of the X^th spectral component and c_xy=β

xy_patch^T*D*β

x_spectral.

15. The image output device color control system according to claim 8, wherein the spectral measurement device is operatively connected in line with the image output device.

16. The image output device color control system according to claim 8, wherein the target color sets comprise a number of colors selected using a low rank approximation algorithm.

17. The image output device color control system according to claim 8, wherein the image output device dependent color space representations comprise one or more GCR (Gray Component Replacement) and UCR (Under Color Removal) sets of image output device dependent color space representations.

18. A xerographic imaging system comprising:

an image marking device;

an in-line spectral measurement device operatively connected to the image marking device; and

a controller operatively connected to the image marking device and spectral measurement device, the controller configured to receive CMYK or RGB data and convert to image output device independent image input data and map the device independent input data to image output device dependent input data for display or printing by the image output device, wherein the controller comprises a controller-usable data carrier storing instructions that, when executed by the controller cause the controller to perform a method comprising;

(a) generating an initial image output device profile LUT (look-up-table) characterizing the color profile of the image output device for a plurality of states associated with the image output device, wherein each state of the image output device LUT associates a first set of target colors with a plurality of respective spectral measurements;

(b) generating a first data matrix representing all spectral measurements associated with each respective target color for all image output device states;

(c) calculating the nominal spectral response associated with each target color;

(d) generating a second data matrix representing the target color spectral variation by subtracting the nominal spectral response from each target color spectral response for each state;

(e) performing a first PCA (Principle Component Analysis) on the second data matrix to represent the image output device profile LUT with a third data matrix including the first set of target colors associated with a predetermined number of spectral directions;

(f) performing a second PCA on each spectral direction associated with the third data matrix to represent the image output device profile LUT with a fourth data matrix including each principle spectral direction associated with the variation of the first set of target colors;

(g) measuring the spectral properties associated with a second set of target colors, the second set of target colors including a subset first set of target colors; and

(h) estimating an image output device profile LUT for the first set of target colors utilizing the third and fourth data matrixes, and the measured spectral properties associated with the second set of target colors.

19. The xerographic imaging system according to claim 18, wherein the first data matrix is represented as D, and the first PCA generates eigenvalues and eigenvectors of D^T D/(M*N), where M equals the number of colors in the first set of target colors and N equals the number of states, and D^T represents the transpose of matrix D.

20. The xerographic imaging system according to claim 19, wherein M is greater than or equal to 100 and N is greater than or equal to 8.