There is provided an image processing apparatus including: a determination unit configured to determine an inclination of a document portion in read image data generated by reading a document based on an inclination of an edge of the document portion detected in the read image data; a correction unit configured to correct the inclination of the determined document portion by a rotation process of the read image data; and a cut-out unit configured to cut out, based on a size of the document portion determined from the detected edge, a partial image of the document portion from the read image data in which the inclination has been corrected.

There is provided an image processing apparatus including: a determination unit configured to determine an inclination of a document portion in read image data generated by reading a document based on an inclination of an edge of the document portion detected in the read image data; a correction unit configured to correct the inclination of the determined document portion by a rotation process of the read image data; and a cut-out unit configured to cut out, based on a size of the document portion determined from the detected edge, a partial image of the document portion from the read image data in which the inclination has been corrected.

An image processing apparatus including: a halftone processing unit configured to generate halftone image data represented by a halftone dot corresponding to a density value by performing halftone processing using a dither matrix for input image data; a phase change processing unit configured to correct a deviation of a laser beam scan line that is used in forming an image in accordance with the input image data on a printing medium by performing phase change processing to shift the phase of a pixel in the halftone image data in a sub scanning direction; and a pseudo high-resolution processing unit configured to convert the halftone image data after the phase change processing into halftone image data with a lower resolution by performing pseudo high-resolution processing, and in the dither matrix, threshold values are arranged so that the number of pixels in the sub scanning direction, which make up the halftone dot, is always even.

An image processing apparatus including: a halftone processing unit configured to generate halftone image data represented by a halftone dot corresponding to a density value by performing halftone processing using a dither matrix for input image data; a phase change processing unit configured to correct a deviation of a laser beam scan line that is used in forming an image in accordance with the input image data on a printing medium by performing phase change processing to shift the phase of a pixel in the halftone image data in a sub scanning direction; and a pseudo high-resolution processing unit configured to convert the halftone image data after the phase change processing into halftone image data with a lower resolution by performing pseudo high-resolution processing, and in the dither matrix, threshold values are arranged so that the number of pixels in the sub scanning direction, which make up the halftone dot, is always even.

An optical scanning apparatus includes a light source having five or more light-emitting portions arrayed in a row, a cylindrical lens, a restricting portion, a polygon mirror, and a plurality of scanning lenses. A plurality of such light sources are provided and each emit light beams. The restricting portion has a plurality of first apertures that restrict the optical path width of the light beams along the sub scanning direction. The first apertures have first openings respectively that penetrate them along the optical axis direction and let the light beams pass through them. The centers of the first openings along the sub scanning direction are disposed displaced along the sub scanning direction.