Algorithm for generating flexographic screen dots

Abstract

To define the appropriate algorithm needed to generate screen dot for flexographic printing. The printed image is compared with that obtained available commercial Flexo software based on tone reproduction. To create the screen, the cluster-dot-ordered dither technique is proposed. This includes screen function, threshold array and multicenter dot. The process has to determine the dot growth sequence of the threshold value and the size of the threshold matrix used to generate round halftone dots. The former is based on spiral dot structure in order to increase dot size until dot joint and to control non-image area of the image. It is found to give the better reproduction. The result shows the capability to retain round shape of dot screen through the tonal range, which resulted in wider tone range for the flexographic printing. The important of these algorithms are the flexibility to design or control shape of dot screen suitable for other printing systems. Another consideration is threshold matrix size used to generate dot screen. Based on 50 lpi, it is found that a 50x50-matrix size is better than a 24x24-matrix size, regarding the tone reproduction.