Screen dot image recording method

Abstract

A screen dot image recording method is disclosed in which whether or not each minimum recording element of an image recording system is to be recorded is determined on the basis of a gray level obtained from an original. A matrix is prepared which has a size capable of including each of screen dot blocks arranged at a predetermined pitch in directions inclined at a predetermined angle with respect to an orthogonal coordinate system based on recording directions of the recording system and has a plurality of matrix elements one of which is defined as a reference element. From among reference points which have a fixed positional relationship therebetween in the screen dot blocks, there is determined a reference point which exists in a screen dot block including a recording element. Another recording element has a coordinate value obtained by converting the coordinate of the determined reference point into an integer value. There is selected a matrix element having a positional relation of that matrix element with the reference element of the matrix which is the same as a positional relation of the recording element with said another recording element. The selected matrix element is compared as a threshold value with a gray level assigned to the recording element to determine whether or not the recording element is to be recorded as a part of a screen dot. Thereby, there is recorded a screen dot image which has any screen angle and any screen pitch and in which each screen dot has a desired form and a desired size corresponding to a gray level.