Abstract
Readability can be defined as the measure of how easy it is to read and comprehend a document. Unfortunately, in the web world, the main colour guidelines given by W3C are not completely informative and they are based on the colour system used by NTSC used in the US television and not valid everywhere (http://www.w3.org/TR/AERT#color-contrast). In order to better determine when a colour combination is readable we fixed a font and a size of the text and then we varied the colour of the strings (evaluated in the CIElab colour system) on a constant background. In our research we tried to individuate the variables determining a good foreground/background colour combination. We first kept the luminance constant and we investigated how geometric distance (ΔE), difference in croma (ΔC) and in hue (ΔH) could have an effect and predict a preference in readability. None of the variables investigate showed a significant result. We then took an account another possibility. We kept constant the croma too and compared colours with a different hue. This approach gave interesting results: colours with an ‘opposite’ hue seemed to gave a good index of readability that gets worse when the colours' hue moves closer.