

JPEGs with Alpha Channels? - ggasp
http://blog.jackadam.net/2010/alpha-jpegs/

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ggchappell
Nice little trick. And pretty useful, too, I imagine.

I suppose the reason JPEG files don't allow for transparency information is
that the DCT would mess it up? (I'm imagining little waves of semi-opaqueness
appearing just outside the boundary of an opaque portion of an image. And
little waves of semi-transparency appearing just inside. Ick.)

Of course, there's no law that says JPEG formats have to use the DCT for
absolutely _everything_. Heck, [ordinary JPEG + PNG mask] probably wouldn't be
a bad file format. Now if we could just get people to start supporting it ....

