T
ext on screen seems to be more sensitive than images. An image is generally quite accommodating, it can be quite fuzzy but still recognisable. But I suppose text performs a more personal function. people want to be able to read it and to feel comfortable when reading it.
Readability is different from legibility, something might be legible but not that easy to read. This can be especially so in colour and there are plenty of myths around about what colour should or should not be used over which. Often when people are talking about colour in this context they refer to hues, words like red, or green.
In fact hue is not particularly significant as regards readability, relative brightness is the crucial thing. If the difference between the brightness of a piece of text and its background is small, in other words if both are of a similar brightness, then it is likely to be more difficult to read than one where the contrast between brightnesses is greater.
This text is readable though may be hard work on the eyes.
This text is less challenging, if maybe less exciting than the one to the left.
Both those panels are the same hues, they are both magenta, (280° on the colour circle), on orange, (35° on the colour circle) – but at different levels of saturation and brightness. You can do this with red and green too, they’re said by some people to be unreadable one over the other, and so they are if the brightness levels are close, but not if the brightnesss levels aren’t close, and note this applies as much to people with colour vision deficiencies as it does to anyone else.
One can start to get into hot water here, because people often like to believe what they have been told by others they regard as experts. Better though to try the experiments.
Note too that where the brightness difference between text and background is small, larger text will be easier to distinquish than text that is smaller.
This text is just about readable though hard work especially in large passages.
This text is less challenging, because it is bigger text than that to the left.
You can experiment with text of one colour over a background of a different colour on my page
Text Readability in Colour. That page allows you to try out text in a colour over a background of a different – or even the same – colour and it programmatically works out how readable it thinks the combination is. I think you will find that the code gets it pretty-well right every time.