[1 4 1]
[4 20 4] : 3 × 3
[1 4 1]
[1 1 1 1 1]
[1 4 4 4 1]
[1 4 12 4 1] : 5 × 5
[1 4 4 4 1]
[1 1 1 1 1]
i don't think this is a fast way of doing it in games, since it takes a whole image (640x480x24) about 1 second to use such a filter......it's the way i do things on my PictureShop.
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Dance with me......
Method I'd figure out is to have 2 images per sprite, other blit normally and other transcluent (the one that only contains some pixels around sprite borders). Anyone got better ideas?
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"Tank, I need an exit. Fast!"
Beyond the naming BS 
, this is a question of having patially transparent pixel around the edges of your sprites. If sprites a rendered in a 3D package, this is easily achieved by rendering on a transparent background, if not, it requires a seriously talented 2D artist .
Anyhow, you need to set each color channel of the destination pixel according to the following eq. (assuming a true color (no palette) mode):
d=(1-a)*d+a*s
where "a" is transparency (1.0 for opaque, 0.0 for transparent), "d" is the destination pixel and "s" is the source pixel.
With respect to performance; it's not a major hit if you only use it for edges, but you can't use HW blitting (and that's a real pain )...
(Note: For real-world use you don't wanna use the eq. above, instead you pre-multiply the transparency on the source image, and then invert it, giving the following equation: d=a*d+s)
/Niels
