On Tue, Sep 13, 2005 at 06:06:14AM +0300, Diaa Sami wrote: > first, I want to thank you for your long and clear response. > > well, you're asking about what I'm trying to achieve. > what I want is to have somekind of transparent color which is written in > the PNG file. > I don't want to have an alpha channel, just that transparent color. > > I'm don't know the details of the PNG file format, but I almost sure it > is possible, because IrfanView does it. > if you want, download that IrfanView, and choose PNG as the saving file > format, you'll find a checkbox called 'save transparent color'.
Ahhh. "tRNS" I haven't looked at that chunk in a long time. Hmm, I hate to
say it, but ImageMagick might be your best bet. I actually wasn't aware of
this particular trick of using tRNS without a PLTE chunk in the image.
Interesting.
Yeah, create the image in GIMP with whatever the color you want to have be
transparent in place, then in ImageMagick, run
convert input.png -transparent color output.png
My initial reaction was that it would be easy to patch the GIMP to mimic
ImageMagick's behaviour, but it really is a can of worms having a color
pretend to be transparent.
Jeff
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