HALFTONE FACSIMILE SIGNAL PROCESSING SYSTEM

PURPOSE:To attain an optimum output signal processing by deciding a block whether its tone change is rapid or slow and deciding whether the block is a dot or not based on the number of times of the change in a signal level between two consecutive picture elements in the block along a prescribed access path. CONSTITUTION:A signal inputted from an input terminal 1 for a halftone facsimile signals is stored in a picture signal memory 2 by plural lines and then read sequentially. A maximum value detection circuit 4 obtains a maximum signal level Lmax in a block, a minimum value detection circuit 5 obtains a minimum signal level Lmin in the block, a subtractor 6 obtains a value of Lmax-Lmin, a deciding circuit 7 compares the said value with a threshold P thereby discriminating that the block is a rapidly changing or a slowly changing block. A main scanning direction number of time of change measuring circuit 8 and a subscanning direction number of change measuring circuit 9 obtain the number of times of signal change caused between predetermined picture elements. A dot deciding circuit 10 discriminates a block whose number of times of change is the threshold P or above as a dot. A signal output circuit 13 outputs a picture signal to an output terminal 14 according to the decision of an output signal decision circuit 12.