Patent ID: 7746500

Claim:
An image forming apparatus comprising: a scanner unit configured to read an original; an image processing unit configured to input image data before image-processing from the scanner and determine whether the original is a monochrome original or a color original by a threshold value; a storage unit configured to store the image data before image-processing a parameter control unit configured to adjust the threshold value and set the adjusted threshold value in the image processing unit; and a printing unit configured to print image data outputted from the image processing unit in a single black color when the original is determined to be a monochrome original, and in multiple colors when the original is determined to be a color original, wherein, when the threshold value is adjusted, an evaluation chart including a major monochrome part and a minor color part is set in the scanner unit and read by the scanner unit, and the parameter control unit performs: a) setting an initial value of the threshold value high enough that the image processing unit determines the evaluation chart is a monochrome original, b) controlling to write image data of the evaluation chart before image-processing into the storage unit, c) controlling to read the image data of the evaluation chart before image-processing from the storage unit, d) sending the read image data of the evaluation chart before image-processing to the image processing unit, e) inputting a determination result of the image processing unit, and f) repeating the step c) through e), while changing the threshold value in a decreasing direction and setting the changed threshold value in the image processing unit, until the image processing unit determines the evaluation chart is a color original.