Method of obtaining white reference data used for correcting non-uniformity in photoelectric cell array

摘要

In an image scan reader, a white reference plate (3) is attached to a transparent plate on which an original is to be placed. Respective optical densities on a plurality of scanning lines (L_A1-L_An, L_B1-L_Bm) are detected, and are averaged within respective regions (R_A, R_B). The maximum values of the respective averaged densities are selected for each pixel to be used for correcting non-uniformity of CCD cells which is employed in reading the white reference plate and the image of the original.