Patent ID: 8963968
Filing Date: 2015-02-24
Classification: G09G,H04N

Abstract:
1. An image processing apparatus which performs a screen process on image data of a plurality of colors using a threshold matrix for each of the colors, the apparatus comprising: an address calculation section which calculates a first address in the threshold matrix based on a position of a pixel in the image data for each pixel; a threshold processor which acquires, from the threshold matrix, a threshold corresponding to the first address, and performs an n-valued process (n≧2) on a pixel value of the pixel using the acquired threshold for each pixel; a shift section which divides the image data into blocks in units of the threshold matrix, determines a shift amount in a main scanning direction and a shift amount in a sub-scanning direction for each of the blocks, and shifts the first address by the shift amounts to form a second address, wherein the threshold processor acquires a threshold corresponding to the second address after the shift by the shift section for the image data of at least one of the colors, and performs the n-valued process using the acquired threshold; and wherein the threshold matrix for a color for the second address has a screen ruling with a lower number of lines than the threshold matrix for a color for which the first address.