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From: "Sam Leffler" <sam@cthulhu.engr.sgi.com>
To: <tiff@sgi.com>, "Michael S. Harrison" <michaelh@dragonseye.com>
Subject: Re: TIFFReadRGBAImage (cont)
Date: Mon, 21 Sep 1998 10:57:54 -0700
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If you provide an image (by ftp please; do not post to this mailing list);
then perhaps
someone can provide a "good solution" to your problem.

    Sam

-----Original Message-----
From: Michael S. Harrison <michaelh@dragonseye.com>
To: tiff@sgi.com <tiff@sgi.com>
Date: Sunday, September 20, 1998 7:02 PM
Subject: TIFFReadRGBAImage (cont)


>this is quite likely a shameless hack, but I found that if I add the
>following code to TIFFRGBAImageBegin, just after the call to get the
>extrasamples, my alpha files are read in and parsed correctly.
>
> if ( img->samplesperpixel == 4 && img->alpha == 0 )
> img->alpha = EXTRASAMPLE_UNASSALPHA;
>
>-------------------------------
>I've run into a problem with TIFFReadRGBAImage where I am trying to load an
>image with alpha information (TIFFTAG_SAMPLESPERPIXEL == 4) and it's
>returning a buffer that has no alpha information.
>
>I've traced it as far as the point where it tries to set the img->alpha
>member using TIFFTAG_EXTRASAMPLES data and that call appears to indicate
>that there's no alpha data (although there is).  As a result,
>pickTileContigCase is calling putRGBcontig8bittile rather than
>putRGBUAcontig8bittile or putRGBAAcontig8bittile.
>
>The file was created with Photoshop for Windows and is read properly by
>both PaintShop and Picture Publisher.
>
>Any help with this problem would be greatly appreciated.
>
>(btw, I'm using 3.4 Beta 37 of the tiff library)
>
>  Michael S. Harrison
>  Dragon's Eye Software
>
>* Custom & Commercial Windows Development
>* From Animation to System Tools
>* http://www.dragonseye.com
>

