| 摘要 |
PURPOSE:To prevent a moire from occurring at the time of halftone picture image scanning in a halftone picture image detector for a scanning paper used for a facsimile terminal equipment, by detecting whether or not the variable point interval of a white and black two-valued picture signal exists within the range of a specified cycle. CONSTITUTION:A picture signal (a) is inputted in a block 1, and a variable point interval signal (b) of positive pulse is outputted at the rise of the picture signal (a). A block 2 outputs a positive reset pulse (c) to a counter 3 at the fall of the signal (b). The counter 3 counts a sampling clock (d) after being reset and outputs a count value N to comparators 4 and 5. The comparator 4 compares the count value N with a set value and outputs a discrimination result (e) of 1, if the count value N is small. The comparator 5 compares the count value N with the set value and outputs a discrimination result (f) of 1, if the N is large. If the signals (b), (e) and (f) become 1 at the same time in an AND gate 6, a halftone detection signal (g) of 1 is outputted. |
