Image forming apparatus

An image forming apparatus comprising:

• a photosensitive member;
• a light source configured to emit a light beam;
• a deflecting unit configured to deflect the light beam so that said photosensitive member is scanned with the light beam emitted from said light source;
• a storing unit configured to store magnification correction data set for each of a plurality of different scanning regions on said photosensitive member with respect to a scanning direction of the light beam;
• a correcting unit configured to correct, on the basis of the magnification correction data stored in said storing unit, image data for each of scanning positions included in a region corresponding to the magnification correction data and configured to output a driving signal on the basis of corrected image data;
• and
• a light source driving portion configured to drive said light source with the driving signal,
• wherein the magnification correction data is determined using a quadratic function of a variable representing the scanning position with respect to the scanning direction,
• wherein a result of an operation performed by the quadratic function represents a correction amount for correcting a magnification of a pixel formed at the scanning position corresponding to the variable, and
• wherein coefficients of two quadratic functions corresponding to adjacent two regions included in the scanning regions are set so that a differential value calculated at the variable corresponding to a boundary of the two regions by a differential of the quadratic function for one region and a differential value calculated at the variable corresponding to the boundary of the two regions by a differential of the quadratic function for the other region are equal to each other.