IMAGE ENCODER, IMAGE DECODER, IMAGE DECODING METHOD, AND IMAGE TRANSMITTING SYSTEM

摘要

An effective picture element detecting means detects the range of effective picture elements of blocks of picture element signals and a two-dimensional orthogonal transforming means performs two-dimensional orthogonal transformation in the smallest units containing all effective picture elements. A DC normalizing coefficient calculating means calculates the distribution of the DC components of the block from the effective picture elements and normalizes the DC components so that the distributions of DC components of the blocks containing different numbers of picture elements may be the same. Orthogonally transformed signals are fed to a quantizing means and the quantizing means quantizes the signals based on weighting factors and quantizing parameters.