Here’s a trick to see faults in a design. Check the grayscale conversion. All touching colors should have a 30-percent differential – especially for text. If something can’t be read in grayscale (no color cues) adjustments need to be made.
There are various ways to convert to grayscale. In this case, I used GIMP (for Linux) and under COLORS used the Desaturation tool to remove all color. If I run over it with the color picker, it gives me percent grayscale.
Set the gamut to CMYK instead of RGB and use the percent “K” (black) to see the percentage grayscale.
I also use Photoshop to do the same trick but just a little different. Again, the color picker will show percent grayscale in a control panel.
Optical, or visual illusions are caused by information gathered by the eye being processed in the brain to cause a perception that does not tally with an actual physical measurement of the object being viewed. Human biology and the mechanism of the human eye create anomalies and make us unreliable witnesses to colour contrasts.
Our eyes recognize edges better without optical popping created by touching colors with low contrast.