Abstract

Any desired screen angle is obtained through calculation for coordinate conversion. Since the screen angle can be set to any desired value for each color used in color recording, a moire can be prevented. The memory capacity required for a memory constituting a threshold table is reduced. The interporation processing is performed to make small an error in calculations. The linear interporation method, the distance allocation method, cubic convolution, etc. are available. Data for respective values of R, G and B in association with the elements of masking equations used in determining Y, M and C, each element including the function of second or higher degrees, have been previously stored in the form of a table, and the respective data obtained by referring to the table with R, G and B as parameters are calculated to obtain Y, M and C.