engleski

Comparative study of offset plate tone value reproduction using different measuring and image processing tools

The quality of tone values on offset printing plate is one of the crucial factors affecting the printed product quality. By implementing Computer to Plate systems tonal values are first formed on a printing plate's surface and therefore their size and shape are one of the crucial factors affecting the printed product quality. In particular, when producing printing plates, a rigorous quality control has to be performed, since any bulk and surface imperfection can have a large detrimental effect on tone value reproduction and thus on print sharpness, contrast, nonuniformity and other print properties. The aim of this paper was to analyse measured results of two different measuring instruments and two different image processing software, determined by two different assessment methods. For direct analysis, of tone value parameters on the printing plate, we have used Techkon spectroplate measuring device with built-in software for image analysis. For indirect analysis, we have used Vitiny VT-300 digital microscope for image recording and microDot software (CC dot) for image analysis. Tools independent software-based image analysis, on all recorded images from both measuring devices, was accomplished using ImageJ, a public domain Java image processing program. This study has shown that indirect and independent image analysis-based evaluation methods proved to be a viable alternative to the established ones on built-in software method with Techkon spectroplate measuring device, providing a reliable tool for the monitoring of the tone value reproduction parameters of offset printing plate.

offset printing plate, measuring device, image-based software, TV reproduction

nije evidentirano