| 摘要 |
PURPOSE:To realize a standard dot angle in color plate making, etc., with the number of the same halftone lines of respective colors by calculating rotational coordinates, in which a theta angle is rotated corresponding to the scanning position coordinates of respective picture elements of an original picture scanned and separated, and converting them to a dot specified concerning a black or white small dot. CONSTITUTION:When a scanning starting signal is inputted to a rotational coordinate arithmetic circuit 1, a picture element clock and horizontal synchronizing signal (x, y) are converted to rotational coordinates (x', y') based on the information of a rotation angle theta and a rotation direction inputted as a parameter. Next, by the rotation coordinates (x', y'), a threshold arithmetic circuit 2 obtains a value (r) and a binarizing circuit 3 binarizes an input image signal and outputs it with the above-mentioned threshold. A binary pattern converting circuit 100 converts and outputs a picture element and the peripheral image element during the present processing to the prescribed picture element pattern in accordance with the above-mentioned image signal level. Thus, respective dots which are a standard dot angle and the same number of halftone lines can be realized.
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