Method for coding image memory

PROBLEM TO BE SOLVED: To shorten the drawing time and plotting time of an image in a memory for refreshing the image on a screen. SOLUTION: An image is provided with a uniformly colored surface demarcated by outlines and the outlines have middle lines and the vicinities of the middle lines having picture elements near by the picture elements of the middle lines. The image contains a filler-plotted feature and one picture element on a screen corresponds to a memory cell containing words one to one. The reading of a present cell constitutes at least part of the information required for writing the corresponding picture element on the screen and memory words recoded with respect to the outlines contain not only those related to the middle lines of the outlines, but also those related to the vicinity of each outline. The code of each recoded memory word has two information bits for discriminating the writing environment of recoded bits.