Method and appartus for converting grey scale values into binary values

摘要

The invention relates to a method for converting grey scale values into binary values in the frequency-modulated rastering of grey scale pictures. The recording area is gaplessly divided into part-fields. To each part-field, a field of threshold values is allocated from a set of stored threshold value fields in accordance with a random selection. Each threshold value field of the set has another preferably randomly changed distribution of the threshold values. The threshold values are compared dot by dot and line by line with the associated grey scale values and on the basis of the comparison, binary values are generated which decide whether a possible exposure point in the recording area is exposed as raster dot or not. IMAGE