# US 6,724,422 B1 · Method for automatically selecting color calibrations > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 6,724,422 B1 - Document ID: US6724422B1 - Status: Granted - Kind: B1 - Application number: 09/646,052 - Filed: 2000-10-25 - Granted: 2004-04-20 - Earliest claimed: 1998-03-12 - Assignees: Heidelberger Druckmaschinen AG - Inventors: Winfried Werner - Web page: https://patentgrep.com/patent/US6724422B1 ## CPC - H04N 1/6083: {controlled by factors external to the apparatus} - H04N 1/603: {controlled by characteristics of the picture signal generator or the picture reproducer} - H04N 1/6077: {Colour balance, e.g. colour cast correction} - H04N: PICTORIAL COMMUNICATION, e.g. TELEVISION ## Abstract In a method for automatically selecting color calibrations for digital color image recording, especially for digital photography or digital video recording in any lighting conditions, at least one color calibration is produced and stored by recording a calibrated color table. The color calibration which best resembles the color cast of a color image is selected on the basis of the correlation between the color cast parameters of the color image which is being recorded and the respective color calibration. In the event that no matching color calibration is found by comparing the color cast parameters, a standard color calibration is selected. ## Claims ### Claim 1 A method for automatic selection of color calibrations for digital color image acquisition under arbitrary lighting conditions and for correction of take data of a color image with the color calibrations based on a color cast compensation and a color transformation, whereby it is not only neutral colors that are utilized for the color cast compensation, comprising the steps of: producing at least one color calibration by acquiring a calibrated color table under defined lighting conditions; implementing an analysis of the color cast of the take data of the color table and determining parameters that describe the color cast of the take data of the color table; undertaking a compensation of the color cast of the take data of the color table; calculating at least one color calibration from the color cast-corrected take data of the color table and storing it; storing the determined parameters of the color cast of the take data of the color table together with the color calibration; determining color cast parameters of the take data of the color image and comparing them to the stored color cast parameters of the color calibrations; and undertaking a selection of a color calibration on the basis of the comparison. ### Claim 2 (depends on 1) The method according to claim 1 wherein the comparison of the color cast parameters is implemented with a correlation. ### Claim 3 (depends on 1) The method according to claim 1 wherein the color calibration whose stored color cast parameters are correlated best with the color cast parameters of the color image is selected. ### Claim 4 (depends on 1) The method according to claim 1 wherein a standard color calibration is selected when an adequately good correlation of the color cast parameters is not found in the comparison of the color cast parameters of the color calibrations and of the color image. ### Claim 5 (depends on 1) The method according to claim 1 wherein the user is informed when an adequately good correlation of the color cast parameters is not found in the comparison of the color cast parameters of the color calibrations and of the color image, so that the user himself can select a suitable color calibration. ### Claim 6 (depends on 1) The method according to claim 1 wherein the color cast parameters of the color image are compared to the color cast parameters of the selected color calibration, and the color cast parameters of the color image are employed for the color cast compensation of the color image given good correlation and the color cast parameters of the selected color calibration are employed for the color cast compensation of the color image given a poor correlation. ### Claim 7 (depends on 1) The method according to claim 1 wherein the comparison and the selection of the color cast parameters employed for the color cast compensation is undertaken separately for the image light area and for the image dark area of the color image. ### Claim 8 (depends on 1) The method according to claim 1 wherein a color transformation of the take data of the color image is implemented with the selected color calibration. ### Claim 9 (depends on 1) The method according to claim 1 wherein at least one additional photographic parameter selected from the group diaphragm, exposure time, distance, flash settings, and time of day of the exposure is involved in the comparison of the color calibrations to the color image. ### Claim 10 (depends on 1) The method of claim 1 wherein the method is employed for at least one of digital photography and digital video recording. ### Claim 11 A method for the automatic selection of color calibrations for digital color image acquisition under arbitrary lighting conditions, and for correction of take data of a color image with the color calibrations on the basis of a color cast compensation, comprising the steps of: producing at least one color calibration by acquiring a calibrated color table under defined lighting conditions; implementing an analysis of the color cast of the take data of the color table and determining parameters that describe the color cast of the take data of the color table; undertaking a compensation of the color cast of the take data of the color table; calculating at least one color calibration from the color cast-corrected take data of the color table and storing it; storing the determined parameters of the color cast of the take data of the color table together with the color calibration; determining color cast parameters of the take data of the color image and comparing them to the stored color cast parameters of the color calibrations; and undertaking a selection of a color calibration on the basis of the comparison.