Patent ID: 6967605
Filing Date: 2005-11-22
Classification: H03M,H04N

Abstract:
1. An image reading apparatus for reading an original, comprising: a light source for scanning the original, a photoelectric converter for converting light reflected from the original in each pixel to an analog signal, an A/D converter electrically connected to the photoelectric converter for converting the analog signal of each pixel from the photoelectric converter to a digital signal, adjusting means electrically connected between the photoelectric converter and the A/D converter for performing an offset processing and a gain processing of the analog signal from the photoelectric converter, a memory electrically connected to the adjusting means for storing a formula representing a correlation between an offset value to be used for the offset processing and a gain value to be used for the gain processing, and offset value calculating means for obtaining the offset value corresponding to the gain value to be used for the gain processing of the analog signal from the photoelectric converter using the formula stored in the memory when the original is scanned so that the gain value and the offset value corresponding to the gain value calculated by the formula in the memory as image data are obtained.