Method for continuous incremental color calibration for color document output terminals
First Claim
1. A color printer color calibration system for updating color calibration values for a color printer, which said color printer during normal printing operations is responsive to device-independent electronic printing signals to print normal color images of selectable combinations of a plurality of printer colorants on print substrates, wherein a device memory controls said color printer by initially storing a look-up table with a large amount of stored information relating said device-independent electronic printing signals to said printing of printer colorants to provide the initial color calibration values for said color printer;
- comprising;
a memory for storing electronic color calibration signals which are suitable for printing color calibration patches with said color printer, a color calibration image generation system for automatically printing plural different color calibration patches on selected said print substrates with said printer colorants from said electronic color calibration signals stored in said memory;
a printer controller controlling said color printer and said color calibration image generation system to print said color calibration patches on selected said print substrates during said normal printing operations;
a color sensor associated with said color printer for measuring the color of a color calibration patch printed on a print substrate by said color printer; and
a converter for sequentially converting said color of said color calibration patch printed on said print substrate measured by said color sensor into an color calibration update value for a small portion of said large amount of stored information in said look-up table, wherein said color calibration image generation system automatically prints different said color calibration patches during said normal printing operations to incrementally update said large amount of stored information in said look-up table relating said device-independent electronic printing signals to said printing of printer colorants during said normal printing operations.
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Abstract
A method and apparatus for continuously upgrading the color calibration for an electrophotographic printer using a color transform look up table stored in memory. A single or small number of color patch samples are printed at regular intervals during the use of the printing machine. The color patches are sensed and a determination made as to the difference between the sensed color and the desired color. A corrective color calibration value is determined for the sensed patch and a correction is made for that color in the printer memory. The process is repeated to assure that all of the colors within the gamut of the machine are continuously updated.
168 Citations
16 Claims
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1. A color printer color calibration system for updating color calibration values for a color printer, which said color printer during normal printing operations is responsive to device-independent electronic printing signals to print normal color images of selectable combinations of a plurality of printer colorants on print substrates, wherein a device memory controls said color printer by initially storing a look-up table with a large amount of stored information relating said device-independent electronic printing signals to said printing of printer colorants to provide the initial color calibration values for said color printer;
- comprising;
a memory for storing electronic color calibration signals which are suitable for printing color calibration patches with said color printer, a color calibration image generation system for automatically printing plural different color calibration patches on selected said print substrates with said printer colorants from said electronic color calibration signals stored in said memory;
a printer controller controlling said color printer and said color calibration image generation system to print said color calibration patches on selected said print substrates during said normal printing operations;
a color sensor associated with said color printer for measuring the color of a color calibration patch printed on a print substrate by said color printer; and
a converter for sequentially converting said color of said color calibration patch printed on said print substrate measured by said color sensor into an color calibration update value for a small portion of said large amount of stored information in said look-up table, wherein said color calibration image generation system automatically prints different said color calibration patches during said normal printing operations to incrementally update said large amount of stored information in said look-up table relating said device-independent electronic printing signals to said printing of printer colorants during said normal printing operations. - View Dependent Claims (2, 3, 4, 5, 6)
- comprising;
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7. A method of updating color calibration values for a color printer, which said color printer during normal printing operations is responsive to device-independent electronic printing signals to print an output of normal color images of selectable combinations of a plurality of printer colorants on print substrates, wherein said color printer is controlled by initially storing a look-up table with a large amount of stored information relating said device-independent electronic printing signals to said printing of printer colorants to provide the initial color calibration values for said color printer;
- comprising;
automatically printing with said printer colorants a limited number of color calibration patches corresponding to desired printer output colors on a limited number of said print substrates during said normal printing operations;
measuring color coordinates of said color calibration patches printed on said print substrates with a color sensor directly associated with said color printer;
converting said color coordinates of a color calibration patch printed on a print substrate as measured by said color sensor into a color calibration update value for said look-up table; and
automatically incrementally repeating during said normal printing operations said printing of limited numbers of additional different said color calibration patches on limited numbers of said print substrates, and automatically repeating said measuring and converting steps therefrom, to incrementally update only a small portion at a time of said large amount of stored information in said look-up table relating said device-independent electronic printing signals to said printing of printer colorants. - View Dependent Claims (8, 9, 10, 11, 12, 13, 14, 15, 16)
- comprising;
Specification