Secret colours of the Commodore 64

This was freaky. When you owned any 8-bit computer, you became intimately familiar with its colour scheme. This simple photograph blew my mind. That blue colour just wasn't possible.According to the caption, by presenting two colours to the eye and alternating them quickly enough, a whole new colour emerged. What would this new, secret colour look like on your crappy early-90s CRT television? The screenshot was only a hint. Would it glow? Would it flicker?Twenty-six years later, I found out the answer.This article is all about colour switching on the Commodore 64. There are interactive examples to play with below. I haven't found anything else on the topic, so it's possible this is the only resource on the subject.It's amazing what talented programmers can eke out of old 8bit machines.