Patent ID: 8189244

Claim:
A calibration system for conducting calibration by using a patch sheet produced on the basis of data to form measurement patches arranged with respective different densities in a predetermined direction and reference patches arranged with a constant density in the vicinity of the measurement patches for each color toner, comprising: a correcting section to correct, on the basis of the colorimetric values of the reference patches, the colorimetric values of the measurement patches arranged in the vicinity of the reference patches, wherein the correcting section calculates an amount of density deviation of each of the reference patches on the basis of the colorimetric value of each of the reference patches and an average value of the colorimetric values of all of the reference patches or a preset value, further calculates for a measurement patch arranged in the vicinity of a reference patch having an amount of density deviation exceeding a criterion value an amount of correction based on the amount of density deviation of the reference patch for the colorimetric value of the measurement patch, and corrects the colorimetric value of the measurement patch on the basis of the amount of correction.