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

摘要

An effective picture element area of a pixel signal at every block is detected at effective pixel detection means, two dimensional orthogonal transformation is done for a minimum unit including all effective pixels at two dimensional orthogonal transform means, a distribution of the DC component which the corresponding block can take from the effective pixels is calculated and the DC component is normalized so that the distributions of the DC components become the same among blocks having different number of pixels at DC normalization coefficient calculation means, and the orthogonal transform signal is supplied to quantization means and quantization is done based on a weighting coefficient and a quantization parameter.