IMAGE READER AND CHROMATIC ABERRATION CORRECTION METHOD

摘要

PROBLEM TO BE SOLVED: To accurately read a color of an image of an original by discriminating a chromatic aberration due to a lens from a chromatic aberration due to the original so as to correct the chromatic aberration. SOLUTION: A CCD line sensor 11 scans a chromatic aberration correction chart. A GCA 30 amplifies an RGB output of the CCD line sensor 11 and an A/D converter 32 converts the amplified RGB output into a digital signal. After shading processing by a shading circuit 34, the processed signal is stored in a line RAM 36. An edge discrimination circuit 38 detects a position of an edge pixel for each RGB output from the image signal stored in the line RAM 36 based on a threshold V1 obtained from a CPU 40 and gives the detected result to a chromatic aberration correction circuit 42. The chromatic aberration correction circuit 42 obtains a chromatic aberration correction coefficient from the position of the edge pixel for each obtained RGB output, and image data obtained by scanning an image of an original by means of the CCD line sensor 11 are corrected based on the chromatic aberration correction coefficient.