Apparatus for dot matrix recording

Abstract

A dot matrix recording system records a wide range of gray levels without compromising recording resolution. Resolution is maintained by using a relatively small dot matrix, preferably a 2 by 2 matrix, for representation of the graphic information at a point within an image being reproduced. When adjacent points within the image have the same optical density, then the matrix representation thereof is altered from point to point so as to produce a matrix of effectively increased size. The larger matrix or matrix group may comprise 4 of the 2 by 2 matrices positioned in a square arrangement. Thus when two horizontally adjacent points within an image have the same optical density and are situated immediately above two other points having the same optical density, then the four-point area is represented by a matrix group comprising a total of 16 matrix cells arranged in a 4 by 4 pattern. Such an arrangement permits recording a gray scale comprising 17 gray levels from white to black, while preserving the resolution afforded by the smaller 2 by 2 matrix. A further gray scale extension is obtained by a 'special case' technique wherein the 2 by 2 matrices are combined into a rectangular matrix group which is 2 matrices high by 4 or 6 matrices wide for a total of 32 or 48 matrix cells.