Colour Gamuts

Today's inkjet printers are capable of producing colour images of very high quality. However, in inkjet printing, the substrate has a large influence on the quality of a printed image. In addition, the large variety of inkjet substrates increases the complexity of the colour reproduction in inkjet printers. Even when high-quality substrates are used, colour management is required when the input data is represented in any of the RGB colour spaces used today. Moreover, colour gamut transformations are inherent as the colour gamut of colour reproduction systems differ in size and shape. In this study, three colour rendering attributes associated with image quality - colour gradation, colour gamut volume and sharpness have been varied prior to printing in a set of test images. In real life, variations in these colour rendition attributes can be caused by different substrate properties, inappropriate printer settings for a specific substrate or the result of shortcomings in colour management. Whatever the cause may be, the effects of these variations can be observed in inkjet-printed images. The colour gamut volume, colour gradation and sharpness were varied simultaneously according to a statistical experimental design thus producing a subset of modified versions for each image in the test set. Furthermore, a visual assessment study was carried out in order to study the effect of the modifications on the perceived impression of the colour rendition in the printed images. Finally, the data from the visual assessment study was analysed in order to reveal how the different attributes influenced the perceived colour rendition.