Details:
Summary:
With dynamic image reproduction it is possible to add more information to the printed product. The print can reveal two or more images in different optical states, thus adding more attention to the final printed product. The dynamic images in this study consist of conventional process ink layers combined with dynamic ink layers that can be brought to different optical states where they display a certain colour or turn transparent, thus revealing the underlying process ink. The dynamic images will be reproduced with more printing primaries than ordinary four process colour printing (CMYK), so called multicolour printing, where every dynamic image requires a unique set and number of printing primaries. There are several problems common to multi-colour printing, which require more complex colour separation algorithms. The complexity of these problems increases as the number of printing primaries grows. When dealing with dynamic image reproduction, the additional requirement to be able to shift between images places completely new demands on the entire colour separation process. For example, it requires a physical model that accurately predicts how arbitrary process and dynamic inks will interact when printed together, in superposition and side by side using halftoning. This paper addresses these challenges and focuses on finding solutions for the colour separation process when reproducing dynamic images using thermochromic inks as dynamic inks in screen printing. Although a great deal more work remains to be done before a complete colour separation model for dynamic image reproduction can be presented, this paper takes some steps towards that goal.