Motion compensated interframe encoding system with adaptive quantization

Claim 1

A picture signal encoding and decoding apparatus comprising an encoding section for conversion encoding with movement compensation and a decoding section, said encoding section having: a movement detecting section for detecting the movement quantity of a digital picture signal; a subtracter for obtaining the difference between said digital picture signal and a predictive signal; an orthogonal transformation section which performs orthogonal transformation to a differential signal obtained from said subtracter; a quantizing section for quantizing a transform coefficient; and means for selecting a predetermined quantization characteristic from a plurality of such characteristics as a function of both the movement quantity detected by said movement detecting section and the sequence of transform coefficients for performing adaptively selected quantization of the transform coefficients, said decoding section having: an inverse orthogonal transformation section for creating a decoded differential signal by inverse orthogonal transformation; an adder for creating a decoded picture signal by adding said decoded differential signal to said predictive signal for movement compensation; and a memory for storing said decoded picture signal and creating said predictive signal for movement compensation according to said movement quantity.