Block transformation coding and decoding system with offset block

Abstract

An image data coding system, wherein an image data in a bit map form is divided into first and second groups, pixels in each group of which are distributed over the whole area of the image data in the bit map form. First and second coders respectively code the first and second groups of image data into first and second groups of coded image data. The first and second groups of image data in the original image data are respectively input into first and second memories, respectively. Blocks of the first group of image data are supplied to the first coder at first times, respectively, and blocks of the second group of image data are supplied to the second coder at second times, respectively. Boundaries of the blocks in the first group of image data are located in different positions from boundaries of the blocks in the second group of image data, and the first times are different from the second times. In the receiver side, first and second decoders respectively decode the above first and second groups of coded image data into first and second groups of decoded image data. By composing the first and second groups of decoded image data, the original image data in the bit map form is restored.