Original determination equipment, document reader, the original determination method and image forming apparatus

摘要

PPROBLEM TO BE SOLVED: To reduce the mistaken decision of the colored original or a colorless original even when the quantity of light differs in a light source irradiating an original. PSOLUTION: An image-reading control unit 110 decides whether or not a gain value adjusted by an analog corrector 102 is less than a gain threshold value 0, and whether or not the gain value is less than the gain threshold value 1 when an ACS (Auto color selection) mode is selected by a user; and sets either of ACS decision parameters 0 to 2 to an ACS 108 in response to the result of the decision. The gain threshold values 0 and 1 represent preset threshold values for deciding whether or not the ACS 108 must decide the original by using the ACS decision parameters 0 or 1 as the combination of a pixel decision threshold value, a colored-pixel number decision threshold value, an original decision threshold value, and an ACS decision region in this case. The ACS 108 decides either of the colorless original or the colored original by using either of the set ACS decision parameters 0 to 2. PCOPYRIGHT: (C)2007,JPO&INPIT