| 摘要 |
PURPOSE:To execute a conversion with a minimum density error by extracting a reference picture element in a range half of the size of a dither matrix from a original picture data, operating, applying a dither processing and outputting a binary picture. CONSTITUTION:When the data of the original picture is inputted to a linear density conversion processing part 3, a position (x, y) on the original picture of a converted picture Q(I, J) is obtained based on a prescribed variable power ratio Cv in a sampling picture element selecting part 4. This position (x, y) is standardized by a distance between the adjacent picture elements of the original picture, and then, x=I/Cv, y=J/Cvo. An original picture element Of(i, j) (reference picture element) the nearest to this converted picture Q(x, y) is obtained and i=[I/Cv], j=[J/Cv] and the square brackets indicate a Gaussian symbol. These data is fed to a reference picture element selecting part 5, an original picture element group including the picture element Of(i, j) is selected as the reference picture element in the range of 2X4 half of the size 4X4 of the dither matrix, arithmetically operated 6, subjected to the dither processing in a dither processing part 7, binarized and outputted as the converted picture. |
