In accordance with an image processing method, a data region is detected from input image data. The input image data is rotated in accordance with inclination of an image. Determination is made whether the data region of rotated image data protrudes from an image area of the input image data. When detection is made of protruding, the smallest area including the data region is extracted from the rotated image data. When the data region of the rotated image data protrudes from the image area of the image data previous to rotation, the smallest region including the data region of the rotated image data is extracted from the rotated image data. Therefore, loosing information from image data subjected to rotational correction can be prevented. Also, the amount of image data subjected to rotational correction can be minimized.