PURPOSE:To improve a picture quality at the time of reproduction by outputting smoothing information for decoding and using by encoding this information when an integrating value of an error between a true signal level of a picture element and an approximately encoded signal level exceeds a prescribed value at a border area of the block. CONSTITUTION:An encoding procedure of tone wedge information and resolution information for four lines is the same as publicly known. Resolution information is written in a memory 12 in respective block units, and in parallel to it, an approximate picture signal level of respective picture elements is selected and outputted and written in a memory 17 by a selecting device 16. After tone wedge information and resolution information for four lines are encoded, a picture signal is read from a memory 1 again, and simultaneously an approximate signal of corresponding picture elements is read from the memory 17, and in an error integrating counting circuit 18, the error with a true signal level is integrated respectively at respective border areas. A comparator 19 decides whether an error integrating value is two or above, the result is written in a memory 20 in the sequence of respective borders, and after that, encoded by an encoder 21 and smoothing information is transmitted to a decoder side.
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