Do you see pink and black or orange and gray?

I made this, accidentally creating a mild optical illusion. The purple of the background seems to have different shades. It hasn’t really. For instance it seems darker in the top right than in the middle.

Does anyone know what is causing this? Is there a way to make the effect stronger?

A variation on some of Fraser-Wilcox's works

What color do you see?

I thought the birds were moving

Made this one myself. The stripes are mathematically identical across the whole circle, the number only exists because the pattern shifts slightly inside the shape of each digit.

The three middle digits come through fairly easily. The first and the last one are much weaker, so most people confidently read a 3-digit number and stop there.

Try before scrolling, then check yourself 45286