Patent ID: 7557960

Claim:
An image forming apparatus, comprising an image processing means for determining a pixel gradation indicating gray level in each pixel based upon a prescribed image data, and an exposing means for writing an electrostatic latent image onto a photoreceptor by exposing a surface of said photoreceptor previously electrified by an electrification means with an exposure amount obtained by transforming said pixel gradation determined by said image processing means, said image forming apparatus further comprising; an individual slope information memory means for individually memorizing said slope information that defines a slope of when said pixel gradation is approximately linear-transformed into said exposure amount within a partial or whole range of said pixel gradation for each segment multi-divided a surface of said photoreceptor, and a means of individual exposure amount transformation for individually transforming said pixel gradation into said exposure amount for each of said segments based upon said slope information, wherein said slope information is an information which, with a reference electric potential that is common between all of said segments, approximately matches an electric potential after exposure of when an exposure amount, obtained by transforming a reference pixel gradation that is common between all of said segments by said means for individual exposure amount transformation, is applied, to an approximately-linear exposure property excepting a converging region to a residual potential, or to a exposure property extending said approximately-linear exposure property by extrapolation operation of above approximately linear exposure property, among exposure properties showing correspondences between exposure amounts and electric potentials after exposure in each of said segments.