US Patent 7379624 Image processing method and apparatus

An image processing method includes the steps of performing resolution conversion processing on input image data to increase the number of grayscale levels, performing edge enhancement processing to increase the number of grayscale levels of the input image data, and performing dithering processing to reduce the number of grayscale levels of each pixel of the input image data. The number of pseudo grayscale levels is determined, based on a combination of a parameter concerning the resolution conversion processing and a parameter indicating the level of the edge enhancement processing.