# US 8,542,410 B2 · Least squares based exposure modulation for banding compensation > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,542,410 B2 - Document ID: US8542410B2 - Status: Granted - Kind: B2 - Application number: 12/555,287 - Filed: 2009-09-08 - Published: 2011-03-10 - Granted: 2013-09-24 - Earliest claimed: 2009-09-08 - Assignees: Xerox Corporation - Applicants: Palghat Ramesh; Peter Paul - Inventors: Palghat Ramesh; Peter Paul - Web page: https://patentgrep.com/patent/US8542410B2 ## CPC - G03G 15/5058: {using a test patch} - G03G 15/0131: {for transferring a pattern to a second base} - G03G 15/0194: {primary transfer to the final recording medium (G03G15/0184 takes precedence)} - G03G 2215/00059: on intermediate image carrying member, e.g. transfer belt - G03G 2215/00067: on recording medium - G03G 2215/0129: horizontal medium transport path at the secondary transfer - G03G 2215/0164: Uniformity control of the toner density at separate colour transfers - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY ## Abstract A method, system, and computer program product for estimating exposure modulation in an image printing system is disclosed. The method includes determining a banding profile for an image printing system by a processor; determining an adjusted exposure modulation profile based on the banding profile using a least squares estimation by the processor; and printing an output based on the adjusted exposure profile. ## Claims ### Claim 1 A method for estimating an exposure modulation in an image printing system comprising at least one marking engine, the at least one marking engine comprising a charging device for charging the image bearing surface, an exposing device for irradiating and discharging the image bearing surface to form a latent image, and a developer unit for developing toner to the image bearing surface, the method comprising: determining, using a processor, a banding profile for an image printing system at different area coverages of a Tone Reproduction Curve (TRC), wherein the procedure of determining the banding profile further comprises: obtaining image data across multiple measurement intervals for each area coverage by one or more sensors, combining the image data with timing information into a coherent signal, and analyzing the coherent signal for periodic and aperiodic components for each area coverage, wherein the periodic components represent the banding profile; determining, using the processor, an adjusted exposure modulation profile based on the determined banding profile using a least squares estimation; and printing an output based on the adjusted exposure modulation profile, wherein the adjusted exposure modulation profile is configured to provide an optimal banding correction across all the area coverages of the TRC. ### Claim 2 (depends on 1) The method according to claim 1, wherein the least squares estimation method is a weighted least squares estimation method, wherein the weights are values assigned for the different area coverages. ### Claim 3 (depends on 2) The method according to claim 2, wherein the weights for the different area coverages are preset in the factory or dynamically adjusted based on a customer image or user input. ### Claim 4 (depends on 1) The method according to claim 1, wherein the aperiodic components of the banding profile represent page-to-page drift variation and lead edge to trail edge variation. ### Claim 5 (depends on 1) The method according to claim 1, wherein the timing information comprises one or more page synchronization signals and/or one or more once-around signals from one or more banding sources. ### Claim 6 (depends on 1) The method according to claim 1, wherein said multiple measurement intervals are at least one of printed pages, interdocuments zones, and customer image zones. ### Claim 7 (depends on 1) The method according to claim 1, wherein said method further comprises applying the adjusted exposure modulation profile to the Tone Reproduction Curve (TRC). ### Claim 8 A system for estimating an exposure modulation in an image printing system: a marking engine; a sensor configured to obtain image data across multiple measurement intervals; an exposing device; and a processor configured to: determine a banding profile for the image printing system at different area coverages of a Tone Reproduction Curve (TRC), wherein to determine the banding profile the processor is further configured to: obtain image data across multiple measurement intervals for each area coverage by one or more sensors, combine the image data with timing information into a coherent signal, and analyze the coherent signal for periodic and aperiodic components for each area coverage, wherein the periodic components represent the banding profile, determine an adjusted exposure modulation profile based on the determined banding profile using a least squares estimation, wherein the adjusted exposure modulation profile is configured to provide an optimal banding correction across all the area coverages of the TRC. ### Claim 9 (depends on 8) The system according to claim 8, wherein the least squares estimation method is a weighted least squares estimation method, wherein the weights are values assigned for the different area coverages. ### Claim 10 (depends on 9) The system according to claim 9, wherein the weights for the different area coverages are preset in the factory or dynamically adjusted based on a customer image or user input. ### Claim 11 (depends on 8) The system according to claim 8, wherein the aperiodic components of the banding profile represent page-to-page drift variation and lead edge to trail edge variation. ### Claim 12 (depends on 8) The method according to claim 8, wherein the timing information comprises one or more page synchronization signals and/or one or more once-around signals from one or more banding sources. ### Claim 13 (depends on 8) The system according to claim 8, wherein said multiple measurement intervals are at least one of printed pages, interdocuments zones, and customer image zones. ### Claim 14 (depends on 8) The system according to claim 8, further comprising a controller configured to apply the adjusted exposure modulation profile to the Tone Reproduction Curve (TRC). ### Claim 15 A non-transitory computer-readable storage medium comprising a computer program product encoded with computer executable instructions that when executed by a processor are configured, to implement a method for estimating an exposure modulation in an image printing system, said method comprising: determining a banding profile for an image printing system at different area coverages of a Tone Reproduction Curve (TRC), wherein the procedure of determining the banding profile further comprises: obtaining image data of images sensed across multiple measurement intervals for each area coverage by a sensor, combining the image data with timing information into a coherent signal, and analyzing the coherent signal for periodic and aperiodic components for each area coverage, wherein the periodic components represent the banding profile; and determining an adjusted exposure modulation profile based on the determined banding profile using a least squares estimation, wherein the adjusted exposure modulation profile is configured to provide an optimal banding correction across all the area coverages of the TRC. ### Claim 16 (depends on 15) The non-transitory computer-readable storage medium according to claim 15, wherein the least squares estimation method is a weighted least squares estimation method, wherein the weights are values assigned for the different area coverages. ### Claim 17 (depends on 16) The non-transitory computer-readable storage medium according to claim 16, wherein the weights for the different area coverages are preset in the factory or dynamically adjusted based on a customer image or user input. ### Claim 18 (depends on 15) The non-transitory computer-readable storage medium according to claim 15, wherein the aperiodic components of the banding profile represent page-to-page drift variation and lead edge to trail edge variation. ### Claim 19 (depends on 15) The non-transitory computer-readable storage medium according to claim 15, wherein the timing information comprises one or more page synchronization signals and/or one or more once-around signals from one or more banding sources. ### Claim 20 (depends on 15) The non-transitory computer-readable storage medium according to claim 15, wherein said multiple measurement intervals are printed pages, interdocuments zones, and/or customer image zones. ### Claim 21 (depends on 15) The non-transitory computer-readable storage medium according to claim 15, wherein said method further comprises applying the adjusted exposure modulation profile to the Tone Reproduction Curve (TRC).