Image processing apparatus including image rotator for correcting tilt of the image data

Abstract

In an image processing apparatus, an image reading unit reads a document put on a platen glass to generate image data, and a detector in the image reading unit detects a tilt angle of the document put on the platen glass. A rotation angle is set based on the image data of a document and the image data is modified according to the rotation angle. The modification is controlled so as not to deteriorate the image quality. For example, the image data is rotated by an angle at which the document is tilted when the document is read, if the detected tilt angle of a document is larger than a predetermined value. The modification of the image data may be controlled according to a characteristic of the image data. For example, the image data is not rotated when the document is decided to include a half-tone image by detecting the attribute of the image data. Preferably, a magnifying power for reading the document is calculated according to the detected tilt angle, and the image data are read again at the magnifying power. Then, the optically magnified image data of the document is rotated by the tilt angle.