IMAGE READER, ITS CONTROLLING METHOD AND RECORDING MEDIUM

摘要

PROBLEM TO BE SOLVED: To obtain the mechanism of an image reader and its control method for improving the gradation resolution of picture data by increasing the number of practical processing bits without increasing the number of system bits to be supplied for the generation of picture data as to an image reader connected to a host device and capable of supplying picture data to the host device and a method for controlling the image reader. SOLUTION: An image is read out on the same scanning line by reading operation based on extended exposure time set up longer than reference exposure time in addition to reading operation allowed to be executed by a reading part 3 built in the image reader 1 on the basis of the reference exposure time. Picture data obtained by reading out a dark image area out of the picture data of individual pixels generated by the image reader 1 are selected to apply the picture data based on the extended exposure time and picture data obtained by reading out a bright image area are selected to apply the picture data based on the reference exposure time.