| 摘要 |
PURPOSE:To inexpensively attain multivalued AD conversion to a still picture high speed picture signal by writing the result of comparison of a comparator to a bit corresponding to a threshold level selected at a comaprison timing and at its point of time. CONSTITUTION:A threshold level 7 at the position of j=1, i=1 is read from a threshold level matrix 10 and fed to a comaprator 12 via a D/A converter 11 and compared with a still picture signal from a CRT display device. A print image buffer 13, based on the result of comparison, writes 1 or 0 in print unit areas E11, E12-corresponding to each dot of the picture signal. Then the CRT display device outputs the picture signal of the same picture again (because of a still picture), a threshold level 8 at the position of j=1. i=2 is read from the matrix 10 and the result of comparison is written in each print unit area E. When the write is finished as to all bits, a printer control circuit 14 controls a printer 15 based on the data in each print unit area E to attain gradation print by the density pattern method.
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