Re: NSImageRGBColorTable crash
Re: NSImageRGBColorTable crash
- Subject: Re: NSImageRGBColorTable crash
- From: Glenn Andreas <email@hidden>
- Date: Mon, 19 Apr 2004 22:26:51 -0500
On 20 apr 2004, at 00.34, Glenn Andreas wrote:
At 11:22 PM +0200 4/19/04, David Remahl wrote:
[[Resend, because the message didn't appear on the list the first time...]]
Has anyone had any success with using NSImageRGBColorTable to generate GIFs?
If tmp is a 768 byte file, containing a color lookup table, the
following will crash:
Have you tried a valid color lookup table?
Yes, I did start off with using a valid color table (the all-white
one was just for demonstration)...It wasn't quite as regular as the
ramp one, because it was generated by the neuquant algorithm, so I
should have thought of using a more typical one. I also explicitly
turned off dithering, and still got the crash.
I have now tried the grayscale one, and it still crashes in
ComputeDither (even with dithering turned off...).
Hm, perhaps "packed RGB" doesn't mean what it sounds like it should mean.
I've tried increasing the size of the file (just in case it was 16
bit components instead of 8 bit components), and it crashes in
InitColorTable, called from NSCompressGIFImage.
I'm not sure if that's an improvement or not.
So I tried changing it to skip the CLUT, and take the NSData it
produces, and recreate the image and dump the clut from there. Turns
out it appears that "packed RGB" is actually suppose to mean "packed
ARGB" (or maybe RGBA), because if I do:
python -c 'f=open("/tmp/clut","w"); f.write("\xff\xff\xff\xff"*256); f.close()'
it seems to work.
--
Glenn Andreas email@hidden
mondo blobbo, Cythera, Theldrow, oh my!
Mad, Bad, and Dangerous to Know
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