Hybrid halftoning, a useful method for flexography

摘要

Most printing devices, such as laser and ink jet printers and many print presses, are restricted to very few colors. The contone images should therefore be transformed into binary ones before being printed. The techniques doing this transformation are referred to as halftoning methods. Halftoning methods can be divided into two main categories, namely AM (Amplitude Modulated) and FM (Frequency Modulated). Some printing methods, such as Flexography, are not able to produce dots sufficiently small in order to handle the highlights and the shadows of the original image by using just an AM halftoning method. In this article we propose a hybrid halftoning method that incorporates AM and FM technologies in order to overcome this problem. The strategy is to use an FM method in the highlights (and the shadows) of the image and an AM method in the rest of the image.