PURPOSE: To realize gradational image recording having a high quality by a small quantity of memory, by storing the number of dots being in an independent relation corresponding to light and shade, when light and shade are expressed by plural dots of different colors.

CONSTITUTION: One dot is further divided into a dot matrix of 4×4. Ternary dots of black, gray and white are distributed to each picture element of this matrix of 4×4. The ternary assignment in the matrix element is allowed 9 to correspond to being easy to become black, grey and white. In case when black, grey and white consist of (x) pieces, (y) pieces and (z) pieces, respectively, (x)+ (y)+(z) are 16. As to which part of the 4×4 matrix black of (x) pieces is assigned, determination is performed automatically in accordance with (x) pieces. Grey of (y) pieces is determined in the same way. Accordingly, the processing can be executed by only storing the number of pieces of black and grey in the image memory.