| 摘要 |
An error adding portion adds together input multi-tone image data and peripheral error information. An adding/subtracting portion adds to or subtracts from multi-tone image data calculated by the error adding portion, a random number in a matrix prepared for each set of pixels of the input multi-tone image data. A quantizing portion quantizes multi-tone image data calculated by the adding/subtracting portion into image data, the number of bits of which image data being smaller than the number of bits of the multi-tone image data calculated by the adding/subtracting portion. An error calculating portion calculates an error based on the multi-tone image data calculated by the error adding portion and the image data quantized by the quantizing portion. An error storing portion stores the error calculated by the error calculating portion for each peripheral pixel. An error operation portion calculates peripheral error information based on the error stored by the error storing portion for each peripheral pixel, and provides the peripheral error information to the error adding portion.
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