PURPOSE: To perform highly efficient transmission possible for picture reproduction with high quality, by determining the share of density of small picture elements with the state of eight adjacent original picture elements, for the picture elements of intermediate density out of picture elements signals encoded and transmitted in 3 levels of white, black and intermediate density.

CONSTITUTION: A reading transmitter 30 transmits readout picture element signals to a reception side via a transmission line after encoding and quantizing in 3 stages of 0, 1 and 2. A signal decoded at a decoder 32 at the reception side is transferred to a buffer memory 33, signals of eight picture elements adjacent to a remarked picture element are picked up from each terminal and the eight picture elements are added at eight adders 34A∼34H. The output sum T1∼T8 of the adjacent eight picture elements of each adder are respectively inputted to a maximum value detection circuit 35 to detect a maximum value TM. Depending on the TM belonging to the sum of 8 picture elements, i.e., either of the T1∼T8, the value of the small picture elements sectioning the remarked picture element into small sections can be determined.