Image forming apparatus and control method thereof

An image forming apparatus, comprising:

• an image carrier that carries an electrostatic latent image formed by irradiated light from a light emitting device;
• a main scanning portion that scans the irradiated light in a main scanning direction of the image carrier,
• a sub-scanning portion that causes a light-receiving surface of the image carrier to move in a sub-scanning direction;
• an irradiated point adjustment portion that adjusts an irradiated point of the irradiated light in the sub-scanning direction so as to correct shift in scanning lines by the irradiated light, which can occur in the sub-scanning direction;
• an interpolation processing portion that, after the irradiated points of the irradiated light have been adjusted, performs interpolation calculations on pixel data of a group of pixels of interest constituted by one or more pixels;
• a phase calculation portion that calculates a shift amount of the scanning lines as phase information and, from the calculated phase information, determines and outputs a first set of coefficients to be supplied to the interpolation processing portion;
• a pattern recognition portion that outputs a pattern recognition rate obtained by performing pattern recognition on a group of pixels of interest and peripheral pixels thereof;
• and
• a correction coefficient output portion that outputs a second set of coefficients to correct the first set of coefficients in accordance with the pattern recognition rate,
• wherein the interpolation processing portion executes interpolation calculations by referring to the first set of coefficients, the second set of coefficients, and the pattern recognition rate.