Patent ID: 8712165
Filing Date: 2014-04-29
Classification: G06K,H04N

Abstract:
1. An image processing apparatus, comprising: a blocking section to block multiple-valued image data by a predetermined plurality of pixels to create a pixel block; an image block average value calculating section to calculate an average value of gradation values of pixels constituting the pixel block blocked by the blocking section; a gradation converting section to quantize the average value of the gradation values calculated by the image block average value calculating section based on a previously determined quantization threshold value; an edge detecting section to detect an edge portion in the pixel block based on the gradation values of the respective pixels constituting the pixel block; a pixel output order pattern setting section to set a first pixel output order pattern of a size same as a size of the pixel block for outputting dots in a descending order of the gradation values based on the gradation values of the respective pixels constituting the pixel block; a pixel output order pattern storage section to store a plurality of second pixel output order patterns, each being a pixel output order pattern of the same size as the size of the pixel block and including a previously determined output order of dots; a pixel output order pattern selecting section to select the first pixel output order pattern set by the pixel output order pattern setting section when the edge detecting section detects the edge portion in the pixel block, the pixel output order pattern selecting section selecting any of the plurality of second pixel output order patterns stored in the pixel output order pattern storage section when the edge detecting section does not detect the edge portion in the pixel block; an image data generating section to generate the image data of the pixel block in order that the dots may be output in conformity with the pixel output order pattern selected by the pixel output order pattern selecting section based on the gradation value obtained by the gradation converting section; and an error diffusion section to diffuse errors before and after the quantization of the average value of the gradation values by the gradation converting section to surrounding pixel blocks of the pixel block subjected to the quantization processing.