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Re: [E-devel] More Tiff loader oddities



On Fri, 19 May 2006 17:04:01 +0100 Simon Wistow <simon@thegestalt.org> babbled:

> On Sat, May 20, 2006 at 12:36:23AM +0900, Carsten Haitzler said:
> > i am going to have to make your day get worse....
> > 
> > "works for me" (tm).
> > 
> > imlib2_view display the same results that gimp and imagemagick display for
> > both tif files. when imlib2_convert runs it converts to just what i'd expect
> > (converting to a png) but png does nuke the pixel values where the alpha
> > value is 0 (so for new_ducked its all blank and for the weird_ducked only
> > the colorwheel contains useful pixels).
> 
> Well, that's better than having to delve around in tiffio.h :)
> 
> You are, of course right.
> 
> What was confusing me was that I have a image_context_set_alpha(0) so I 
> was assuming that it would be ignoring the alpha when I saved out as, 
> say, jpg.

ooh no - jpeg cannot contain alpha. when u set alpha to 0 - imlib2 just
"ignores" the alpha channel entirely so if there was pixel rgb values where
before there was alpha - you get the pixels back :) if that's not what you want
- you want to blend the image onto some pre-defined solid background (often
image display apps use a grey checkerboard to indicate that those parts were
transparent). then save the result :)


-- 
------------- Codito, ergo sum - "I code, therefore I am" --------------
The Rasterman (Carsten Haitzler)    raster@rasterman.com
裸好多
Tokyo, Japan (東京 日本)