| 摘要 |
PURPOSE: To eliminate uneven density and deterioration in image quality of a halftone image by applying multi-value dither matrix processing to image data with a gradation lower than a prescribed gradation before gradation conversion matching the image data with the gradation capability of a recording head. CONSTITUTION: An image processing circuit 1 sends received image data to a 1×1 matrix 2A/2×2 matrix 2B depending whether the gradation is more/less than a prescribed threshold level set by a threshold level setting circuit 7. The matrix 2A gives the image data to a gradation conversion circuit 3 without special processing, and the matrix 2B applies multi-value dither matrix processing to the image data and gives the resulting data to the circuit 3. The circuit 3 converts 0 to 255 gradation of input image data into 0 to 31 gradation capable of being processed by an LED array head 5. The signal is given to a head controller 4, in which P/S conversion is applied to the signal, the head 5 is driven, a control section 6 controls the entire circuit and sets a threshold level of the circuit 7. Thus, uneven density of background is eliminated and beautiful images as a whole are generated.
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