PURPOSE: To reduce the scale of hardware for a mode discrimination section by using a prediction error already calculated for motion prediction for the discrimination of the inter-frame coding mode and the in-frame coding mode, thereby eliminating circuits for sum of products arithmetic operation having been required for a conventional coder.
CONSTITUTION: In-frame blocks X are fed to an image input terminal 1 in a prescribed sequence, and fed to a subtractor 2, in which the block X is taken of a difference from a prediction block P whose motion is predicted and calculated based on a reference image stored in a prediction section 11 and from which an inter-frame difference block E is outputted in the order of a prescribed image. A control section 4 receives the block X and a predicted error PE from the prediction section 11 and compares a predicted error based on the error PE and an in-frame random quantity to code the block X or the block E through the control of a changeover device 3. The selected block E is given to a coding section 5, from which coded data Y are given to a multiplexer 6 and a decoding section 8.
MIYAKE TOSHIYUKI
KATADA HIROYUKI
AONO TOMOKO
KUSAO HIROSHI
