It takes a color in and applies an XOR mask just like a regular XOR would a bit mask, except it is on the RGB colors, so it produces the color you pass in if it overlays a color with the same values or the inverse of that colors RGB and and color below its RGB if the values are different.
Just write some code and try it and it will be immediate evident what happens.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…