Digital imaging color calibration

• US 6,262,810 B1
• Filed: 09/11/1997
• Issued: 07/17/2001
• Est. Priority Date: 09/11/1997
• Status: Expired due to Fees

• Current Assignee: Ricoh Corporation (Ricoh Company Limited)
• Original Assignee: Ricoh Corporation (Ricoh Company Limited)
• Inventors: Bloomer, Richard S.
• Primary Examiner(s): NGUYEN, ANH-VINH THI
• Application Number:
  US08/927,346
• Time in Patent Office: 1,405 Days
• Field of Search: 358/519, 358/520, 358/518, 358/522, 358/521, 358/523, 358/524, 358/525, 358/527, 358/504, 358/1.9, 358/1.8, 358/1.1, 358/1.16, 358/1.17, 382/167, 382/162, 382/274
• US Class Current: 358/1.9
• CPC Class Codes: H04N 1/6033 using test pattern analysis H04N1/6055 takes precedence

Abstract

The present invention relates to a method of determining optimum color density and gamma curves and includes a step of providing a first set of input color values representing a set of Cyan, Magenta and Yellow values corresponding to a desired output color. An array of color output simulations is output using the first set of input color values, the array consisting of a plurality of individual color samples having varying amounts of Cyan, Magenta and Yellow which differ by predetermined percentages. The sample which corresponds most closely with the desired output color is selected and the Cyan, Magenta and Yellow values corresponding to the sample are determined. The gamma correction curves which are used to adjust the input color values are adjusted by using the determined Cyan, Magenta and Yellow values.

Claims

1. A print utility allowing an end user to adjust gamma correction curves, said utility comprising steps of:

inputting a first set of color values representing a set of Cyan, Magenta and Yellow values corresponding to a desired output color;

outputting an array of color output simulations using the first set of color values, the array consisting of a plurality of individual color samples having varying amounts of Cyan, Magenta and Yellow which differ by predetermined percentages, the output array including information identifying the varying amounts of Cyan, Magenta and Yellow of each individual color sample, said outputting step varying an optimum maximum density value of each of Cyan, Magenta and Yellow by a predetermined amount for each color sample;

selecting the sample which corresponds most closely with the desired output color and determining from the identifying information optimum maximum density values for the Cyan, Magenta and Yellow values corresponding to the selected sample; and

adjusting gamma correction curves which are used to adjust input color values by using the determined optimum maximum density values for the Cyan, Magenta and Yellow values corresponding to the selected sample to alter the optimum maximum density value for each input color value by a predetermined amount.

2. A print utility as recited in claim 1, wherein the first set of color input values are derived from a desired color, the desired color being selected from a predetermined standard.

3. A print utility as recited in claim 2, wherein the predetermined standard is the PANTONE color matching system.

4. A print utility as recited in claim 2, wherein the predetermined standard is SWOP.

5. A print utility as recited in claim 1, wherein the outputting step comprises printing a plurality of combination color samples, each sample consisting of eight different combinations of Cyan, Magenta and Yellow.

6. A print utility as recited in claim 5, wherein the outputting step comprises printing an eight by eight array of color samples.

7. A print utility as recited in claim 6, wherein the eight by eight array consists of eight rows and eight columns and wherein at least one of the CMY values varies for each column and another of the CMY values varies for each row.

8. A print utility as recited in claim 7, wherein each sample is further divided into a plurality of segments, and another of the CMY values varies for each segment.

9. A print utility as recited in claim 1, wherein the adjusting step adjusts the dot gain values of the gamma correction curves.

10. A print utility as recited in claim 1, wherein said outputting step comprises varying the dot gain of each input color value by a predetermined amount for each color sample.

11. A print utility as recited in claim 10, wherein said adjusting step comprises altering the dot gain for each of the gamma correction curves based in the selected sample.

12. A print utility as recited in claim 1, wherein the adjusting step adjusts the optimum maximum density values of the gamma correction curves.

13. A print utility allowing an end user to perform spot color dot gain adjustment, said utility comprising the steps of:

inputting a first set of color values representing a set of Cyan, Magenta and Yellow values (CMY values) that correspond to a desired output value;

outputting an array of color output simulations using the first set of color values, the array consisting of a plurality of individual color samples having varying amounts of Cyan, Magenta and Yellow which differ by predetermined percentages, the output array including information identifying the varying amounts of Cyan, Magenta and Yellow of each individual color sample, the outputting step printing an array of combinations of color samples, each sample consisting of different combinations of Cyan, Magenta and Yellow, the array including rows and columns, wherein an optimum maximum density value of at least one of the CMY values varies for each column and an optimum maximum density value of another of the CMY values varies for each row;

selecting a sample which corresponds most closely with the desired output color and deriving optimum maximum density values for the Cyan, Magenta and Yellow values corresponding to the selected sample from the identifying information; and

adjusting gamma correction curves for each of Cyan, Magenta and Yellow using the derived optimum maximum density values for the Cyan, Magenta and Yellow values corresponding to the selected sample, the gamma correction curves being used to adjust the color input values.

14. A print utility as recited in claim 13, wherein a spot color dot gain adjustment is performed by using the derived CMY values to adjust the dot gain for each of the CMY curves.

15. A print utility as recited in claim 13, wherein a maximum optimum density is adjusted for each color by using the derived CMY values to adjust the maximum density for each of the CMY curves.

16. A print utility allowing an end user to adjust gamma correction curves, said utility comprising steps of:

inputting a first set of color values corresponding to a desired output color;

outputting an array of color output simulations using the first set of color values, the array consisting of a plurality of individual color samples having varying amounts of colors which differ by predetermined percentages, the outputting step varying an optimum maximum density value of each input color value by a predetermined amount for each sample;

selecting the sample which corresponds most closely with the desired output color and determining optimum maximum density values for each color from the selected sample; and

adjusting gamma correction curves which are used to adjust input color values by using the determined optimum maximum density values for each color from the selected sample.

17. A print utility allowing an end user to adjust gamma correction curves, said utility comprising steps of:

inputting a first set of color values representing a set of colors used to output a desired output color;

outputting an array of color output simulations using the first set of color values, the array consisting of a plurality of individual color samples having varying amounts of colors which differ by predetermined percentages, the outputting step outputting an array including a plurality of combination color samples, each sample consisting of different optimum maximum density values of combinations of colors, the array consisting of rows and columns and wherein an optimum maximum density value of at least one of the color values varies for each column and an optimum maximum density value of another of the color values varies for each row;

selecting the sample which corresponds most closely with the desired output color and determining optimum maximum density values of the selected sample; and

adjusting gamma correction curves which are used to adjust input color values by using the determined optimum maximum density values of the selected sample.

18. A print utility as recited in claim 17, wherein each sample is further divided into a plurality of segments, and wherein an optimum maximum density value of another of the color values varies for each of the plurality of segments.

19. A print utility allowing an end user to perform spot color dot gain adjustment, said utility comprising the steps of:

inputting a first set of color values representing a set of colors that correspond to a desired output value;

outputting an array of color output simulations using the first set of color values, the array consisting of a plurality of individual color samples having varying amounts of the colors and which differ by predetermined percentages, the outputting step outputting an array of combinations of color samples, each sample consisting of different combinations of colors, the array including rows and columns, wherein a dot gain of at least one of the color values varies for each column and a dot gain of another of the color values varies for each row;

selecting a sample which corresponds most closely with the desired output color and deriving dot gains of the resulting color values corresponding to the selected sample; and

adjusting gamma correction curves for each of the colors using the derived dot gains of the resulting color values corresponding to the selected sample, the gamma correction curves being used to adjust the color input values.

20. A computer readable medium containing a print utility allowing an end user to adjust gamma correction curves, said computer readable medium comprising instructions for:

receiving a first set of color values representing a set of Cyan, Magenta and Yellow values corresponding to a desired output color;

outputting an array of color output simulations using the first set of color values, the array consisting of a plurality of individual color samples having varying amounts of Cyan, Magenta and Yellow which differ by predetermined percentages, the output array including information identifying the varying amounts of Cyan, Magenta and Yellow of each individual color sample, said outputting step varying an optimum maximum density value of each of Cyan, Magenta and Yellow by a predetermined amount for each color sample;

receiving information indicating a selected sample which corresponds most closely with the desired output color;

identifying optimum maximum density values for the Cyan, Magenta and Yellow values corresponding to the selected sample; and

adjusting gamma correction curves which are used to adjust input color values by using the identified optimum maximum density values for the Cyan, Magenta and Yellow values corresponding to the selected sample to alter the optimum maximum density value for each input color value by a predetermined amount.

21. A computer readable medium containing a print utility allowing an end user to perform spot color dot gain adjustment, said computer readable medium comprising instructions for:

receiving a first set of color values representing a set of Cyan, Magenta and Yellow values (CMY values) that correspond to a desired output value;

outputting an array of color output simulations using the first set of color values, the array consisting of a plurality of individual color samples having varying amounts of Cyan, Magenta and Yellow which differ by predetermined percentages, the output array including information identifying the varying amounts of Cyan, Magenta and Yellow of each individual color sample, wherein an array of combinations of color samples are output, each sample consisting of different combinations of Cyan, Magenta and Yellow, the array including rows and columns, wherein an optimum maximum density value of at least one of the CMY values varies for each column and an optimum maximum density value of another of the CMY values varies for each row;

receiving information indicating a selected sample which corresponds most closely with the desired output color;

identifying optimum maximum density values for each of the Cyan, Magenta and Yellow values corresponding to the selected sample from the identifying information; and

adjusting gamma correction curves for each of Cyan, Magenta and Yellow using the identified optimum maximum density values for the Cyan, Magenta and Yellow values corresponding to the selected sample, the gamma correction curves being used to adjust the color input values.

22. A computer readable medium containing a print utility allowing an end user to adjust gamma correction curves, said computer readable medium comprising instructions for:

receiving a first set of color values corresponding to a desired output color;

outputting an array of color output simulations using the first set of color values, the array consisting of a plurality of individual color samples having varying amounts of colors which differ by predetermined percentages, wherein the outputting varies an optimum maximum density value of each input color value by a predetermined amount for each sample;

receiving information indicating a selected sample which corresponds most closely with the desired output color;

identifying optimum maximum density values for each color from the selected sample; and

adjusting gamma correction curves which are used to adjust input color values by using the optimum maximum density values identified for each color from the selected sample to alter the optimum maximum density value for each input color value by a predetermined amount.

23. A computer readable medium containing a print utility allowing an end user to adjust gamma correction cures, said computer readable medium comprising instructions for:

inputting a first set of color values representing a set of colors used to output a desired output color;

outputting an array of color output simulations using the first set of color values, the array consisting of a plurality of individual color samples having varying amounts of colors which differ by predetermined percentages, the output array including a plurality of combination color samples, each sample consisting of different optimum maximum density value of combinations of colors, the array consisting of rows and columns and wherein an optimum maximum density value of at least one of the color values varies for each column and an optimum maximum density value of another of the color values varies for each row;

receiving information indicating a selected sample which corresponds most closely with the desired output color;

identifying optimum maximum density values of the selected sample; and

adjusting gamma correction curves which are used to adjust input color values using optimum maximum density values of the selected sample.

24. A computer readable medium containing a print utility allowing an end user to perform spot color dot gain adjustment, said computer medium comprising instructions for:

inputting a first set of color values representing a set of colors that correspond to a desired output value;

outputting an array of color output simulations using the first set of color values, the array consisting of a plurality of individual color samples having varying amounts of the colors and which differ by predetermined percentages, by outputting an array of combinations of color samples, each sample consisting of different combinations of colors, the array including rows and columns, wherein a dot gain of at least one of the colors values varies for each column and a dot of another of the color value varies for each row;

receiving information indicating a selected a sample which corresponds most closely with the desired output color;

identifying dot gains of color values corresponding to the selected sample; and

adjusting gamma correction curves for each of the colors using the derived dot gains of the color values, corresponding to the selected sample the gamma correction curves being used to adjust the color input values.