Patent ID: 7924464
Filing Date: 2011-04-12
Classification: H04N

Abstract:
1. An image processing method of processing image data indicative of an image represented with a prescribed number of input tones by each of pixel groups composed of a plurality of print pixels, and generating dot data representing a status of dot formation on each of the print pixels to be formed on a print medium, the method comprising: preparing a first conversion table containing first correspondence relationships of pixel group tone values representing tone values of the pixel groups and multi-value quantization result values assuming a prescribed range of values, the first correspondence relationships being prepared for each of the pixel groups; preparing a second conversion table containing second correspondence relationships of output dot arrangements indicative of dot states for each pixel in the pixel groups and the multi-value quantization result values, the second correspondence relationships being prepared for each of the pixel groups; determining the pixel group tone value in response to input tone values corresponding to the pixel group, among the image data; converting the determined pixel group tone value into the multi-value quantization result values for each of the pixel groups, by referring to the first conversion table; transforming the acquired multi-value quantization result value into the output dot arrangement for each of the pixel groups, by referring to the second conversion table; and outputting the dot data in response to the output dot arrangement, wherein the first correspondence relationships and the second correspondence relationships are configured to make a state of dot formation close to either one of blue noise characteristics and green noise characteristics over a whole range of the input tone values, wherein dot positions of at least part of the output dot arrangements are changed within each pixel group so that a decrease of a granularity evaluation value of the state of dot formation to a granularity evaluation value of the state of dot formation provided by referring to the first and second conversion table is not greater than a preset value to make the state of dot formation closer to either one of blue noise characteristics and green noise characteristics with regard to a partial range of the input tone values corresponding to each of the output dot arrangements, wherein the second conversion table includes a third conversion table and a fourth conversion table, the third conversion table containing third correspondence relationships of dot count data indicative of numbers of multiple dot sizes and code values, the fourth conversion table containing fourth correspondence relationships of order value matrixes indicative of sequential orders of pixels for dots to be formed in the pixel group and the multi-value quantization result values, the fourth correspondence relationships being prepared for each of the pixel groups, wherein the transforming includes: wherein each of the operations of the image processing method is executed by a processor.