| 摘要 |
PROBLEM TO BE SOLVED: To realize a good gradation representation over the entire range of pixel value of pixels included in an original image. SOLUTION: Based on the thermal transfer characteristics of a thermal head or an ink sheet, normal sections (e.g. 16-240) capable of stabilized gradation control, and first specific sections (e.g. 1-15) and second specific sections (e.g. 241-254) where gradation control becomes unstable are set for 8 bit pixel values 0-255. For pixels having a pixel value in the normal section, full tone print for sublimation transferring a quantity of ink depending on the pixel value is carried out as usual. For pixels having a pixel value in each specific section, halftone printing is performed by selecting any one of alternative pixel values 0 and 16 or 240 and 255 with a probability corresponding to the pixel value. A dither mask for halftone processing is utilized for determining the selection. COPYRIGHT: (C)2004,JPO
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