Comments on Electronic Techniques for Pictorial Image Reproduction

The role of dither threshold matrices has not been paid much attention in a recent paper [1]: These comments highlight the useful features of the so-called Nasik pattern as a threshold matrix. It is shown that the total number of Nasik type matrices is 384. The properties of Nasik patterns are invariant to dyadic shifts. Hence, random selection of matrices and adaptive selection schemes can be devised, resulting in a minimization of texture and good rendition of details.