[BUG] GIFReadWriter - degradation on writing

Andreas Raab andreas.raab at gmx.de
Thu Aug 7 21:10:48 UTC 2003


Interesting. That's a bug. GIFReadWriter tries to reduce the color count of
the image being written (e.g., when you write form > 8bpp) and apparently
that's broken for ColorForm. It's not quite clear how to fix this though. We
either need to find out what breaks in colorReduced and/or simply disable
the call in GIFReadWriter for forms <= 8bpp.

Cheers,
  - Andreas

> -----Original Message-----
> From: squeak-dev-bounces at lists.squeakfoundation.org 
> [mailto:squeak-dev-bounces at lists.squeakfoundation.org] On 
> Behalf Of tblanchard at mac.com
> Sent: Thursday, August 07, 2003 10:19 PM
> To: The general-purpose Squeak developers list
> Subject: Re: [BUG] GIFReadWriter - degradation on writing
> 
> 
> 
> On Thursday, August 7, 2003, at 02:09  PM, Ned Konz wrote:
> 
> > On Thursday 07 August 2003 12:44 pm, tblanchard at mac.com wrote:
> >> I don't know a whole lot about image file formats but I've noticed
> >> that gifs written with GIFReadWriter end up looking worse than when
> >> they were read.  The (hopefully still) attached image illustrates
> >> the problem.
> >
> > How did the images look in Squeak?
> 
> Fine.  Only on writing did it get ragged.
> 
> > You attached a PDF, not a GIF.
> 
> Yes, that's what OS X uses as its screen capture format.  If you view 
> it full size, you can see from left to right the original image, the 
> written back ragged image, and the view of the image in squeak.  (I 
> overlaid the windows to get that shot) It definitely gets worse on 
> writing.
> 
> > And I'm not sure what it was, or how you made it, or what you don't
> > like about it, or what it looked like originally.
> 
> OK, again - the middle one's characters look much more 
> pixellated than 
> either the original gif (on the left) or the squeak rendering of the 
> gif (on the right).
> 
> > Can you attach "before" and "after" gifs?
> 
> Yes - one is clearly (on my screen anyhow) smoother looking than the 
> other.
> 
> 



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