Details:
Summary:
In an earlier trial, an eight-page sample was printed on five different newsprint substrates with cold or heat set inks. A direct correlation was found between the value added based on visual assessment and both the chroma of individual colours and colour gamut of the printed product. This paper reports the results of the follow on study undertaken to extend the work to cover UV inks and to obtain more colorimetric and print process data. The images on the sample were changed in light of the experiences from the first trial to include both high and low key images, thus allowing the assessment of images that would be more difficult to print, yet were of potentially commercial significance. An IT8 target and other colour scales were also included to allow for the analysis of tone gain, as well as solids and overprints. Bespoke software was used to obtain colour gamut information directly from the printed images. The tone value increase was found to be highly dependent on the ink and paper combination. The heatset ink had the less tone value increase compared to the UV ink. Measurement of the physical dot area highlighted that this was in part due to reduced penetration into the substrate and thus the ink density remained high for a given dot area. The results highlighted the complex three dimensional shape of the colour gamut of the printing process and the limitations of using solids and overprints to characterize the prints.