Am 01.03.2011 06:14, schrieb Scott M:

> No more corruption of my images with mysterious black bands. Goodness reigns.

Good to know. So whatever it was, I must have fixed it ;-)


> But it's not a proper .bmp, at least according to the sources at
> http://en.wikipedia.org/wiki/BMP_file_format
>
> To contain transparency, you are supposed to move up to the 108 byte header, and
> specify the masks for red, green, blue and alpha. Without those masks, there's
> no way to tell which bits represent which colors. I'm willing to bet there's
> code out there that assumes it must be 8.8.8.8.0 if there's no masks present, so
> probably many tools will work with these .bmps anyway, but that doesn't make it
> right.

You live and learn - I didn't even know that there /is/ some official 
way of supporting an alpha channel with bmp. I was always convinced it 
was a hack format that makes use of the padding byte of the 
pad-to-32-bit variant of BMP (Well, in the case of POV-Ray it apparently 
is).

Thanks for the pointer, I'll keep that in mind when I re-visit file output.

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