Patent ID: 7580156

Claim:
An image processing system for performing specific image processing on image data and for outputting dot data for forming dots on a recording medium based on the results of said image processing system, comprising: correspondence relationship preparation unit that prepares in advance, for each group of pixels, each comprising a plurality of pixels, a correspondence relationship between a representative tone value, which is a tone value that represents said group of pixels, and a multilevel halftoning resultant value that represents the results of performing multilevel halftoning on each individual pixel that structures said group of pixels, wherein each of a plurality of correspondence relationships is defined as groups of threshold values that group together a number of threshold values equal to the number of pixels included in said group of pixels, and said plurality of correspondence relationships is prepared comprising threshold values with different values from a plurality of individual threshold values selected from a global dithering matrix having included therein a number of threshold values that is larger than a number of tones in an image, laid out following specific characteristics, while varying the order of the extraction locations; representative tone value determining unit that splits said groups of pixels, sequentially extracted from said image, into a plurality of regions and, for each region, determining a representative tone value for representing the tone value of said region; multilevel halftoning unit that uses said determined representative tone values for each region to obtain a multilevel halftoning resultant value, for each of said regions, through referencing said correspondence relationships assigned to said groups of pixels belonging to said regions; sequence value specifying unit that specifies sequence values that indicate the sequence in which will be formed the dots in each pixel in said pixel groups according to the correspondence relationships referenced when obtaining said multilevel halftoning resultant values; dot data generating unit that generates dot data indicating whether or not to form a dot for each pixel within each of said regions based on said specified sequence value for said group of pixels to which region belongs and on said multilevel halftoning resultant values obtained for each of said regions; and output unit that outputs said dot data.