Bildsignalkorrekturverfahren

摘要

Disclosed herein is a method of correcting an image signal, which is suitable for use in reading an image by an image sensor having a black reference pixel and effective pixels. This method comprises a first process for determining initial offset data from the black reference pixel and determining such first correction data that values outputted from all the effective pixels of the image sensor are identical to each other at the exposure greater than the minimum value of an exposure range required to read the image and smaller than the maximum value of the exposure range necessary to read the same; a second process for determining the latest offset data from the black reference pixel; a third process for determining offset correction data from the difference between the latest offset data and the initial offset data; a fourth process for determining image data from the effective pixels of the image sensor upon reading the image borne by an original; a fifth process for adding the first correction data to the offset correction data to obtain second correction data; and a sixth process for subtracting the second correction data from the image data to obtain image data subsequent to correction processing. In addition, this method includes a seventh process for performing shading correction of the image data obtained in the sixth process.