Red feather

The Problem
You want to feather your image to look like the one on the right, but instead you ended up with an image like the one on the left. What happened? You probably placed your feathered image on top of a red (or green, or blue) background thinking that you were later going to mark red as transparent. When you told your transparency program to make red transparent, though, it only marked one shade of red (i.e. 255,0,0 or 0xff0000). Feathering works by interpolating between foreground and background, so there are several shades of red present that are not exactly 0xff0000 (that can't all be marked as transparent).

The Solution
See the section on feathering in the Advanced Examples.

Halo bender

The Problem
The effect is subtle, but if you look at the image on the left, you'll notice a slight halo effect around the swirly shape. If you look closely, you'll see that some of the pixels on the border between the swirl (which is 100% black) and the (simulated) page background (which is 25% black) are of shades that are not between 25 and 100% black.

This is because the postscript swirl shape was rasterized on a white background, so pixels padding the foreground and background are anywhere between 0% black and 100% black.

Comments? Last modified: Thu Jun 20 16:07:38 1996