10.5. The feComponentTransfer Filter

The problem with the background is that it is too dark. Using saturate isn't the answer; it raises or lowers all the color levels. What we need to do is increase the level of green and red more than the blue level, and the <feComponentTransfer> element lets us do just that.

You adjust the levels of red, green, blue, and alpha by placing a <feFuncR>, <feFuncG>, <feFuncB>, and <feFuncA> element inside the <feComponentTransfer>. Each of these sub-elements may independently specify a type attribute that tells how that particular channel is to be modified.