Patent ID: 7483185

Claim:
A method of calibrating image luminance values, comprising: scanning N calibration charts to obtain N actual luminance values, wherein N is a positive integer larger than 2, the N actual luminance values include 1 st to N th actual luminance values, and the (i+1) th actual luminance value is larger than the i th actual luminance value where i ranges from 1 to N-1; scanning a document to obtain a scan luminance value; providing N ideal luminance values corresponding to the N calibration charts, wherein the N ideal luminance values include 1 st to N th ideal luminance values, the (k+1) th ideal luminance value is larger than the k th ideal luminance value where k ranges from 1 to N-1, and the 1 st to N th ideal luminance values correspond to the 1 st to N th actual luminance values; comparing the scan luminance value with the N actual luminance values; determining a j th actual luminance value and a (j+1) th actual luminance value for the scan luminance value, where j ranges from 1 to N-1, wherein the scan luminance value is smaller than the (j+1) th actual luminance value and larger than or equal to the j th actual luminance value; and determining the calibrated luminance value according to the j th actual luminance value, the (j+1) th actual luminance value, the j th ideal luminance value, the (j+1) th ideal luminance value and the scan luminance value.