NYCPHP Meetup

[Chris Bielanski]

Let me see if I follow the sordid details as Jeff opened them...

I am of the understanding that the GIF format is a bitmap compressed with
run-length encoding (RLE). What I don't really have information about is
this: Does Recursive-RLE mean LZW and vice versa? 

Maybe I should re-read or find anew the whitepapers I consumed a couple
years back when I was going to make a realtime palette-rotator for GIF
images. and some more on the Lempel-Ziv and Lempel-Ziv-Welch algorithms. The
sad part is I can remember what the alphabet soup means, and can even
visualize the chunk processing for loading a gif-stream, but I coulnd't tell
you what LZW actually is, or how it applies to GIF formatting.

Also, how does PNG compress itself without using LZW?


Thanks,
Chris Bielanski
Web Programmer, 
International Trademark Association,
1133 Avenue of the Americas, 33rd Floor
New York, NY 10036
+1 (212) 642-1745, f: +1 (212) 768-7796
mailto:cbielanski at inta.org, www.inta.org  
INTA -- 125 Years of Excellence



> -----Original Message-----
> From: putamare [mailto:jeffknight at mac.com]
> Sent: Friday, June 25, 2004 1:49 PM
> To: NYPHP Talk
> Subject: Re: [nycphp-talk] Gif -> Png or Jpeg
> 
> 
> It all depends on what libraries you have installed. Many 
> installations 
> of the gd library include gif read support.
> 
> What is the output of
> <?PHP print_r(gd_info()); ?>
> on your sever?
> 
> The patent that prevents the inclusion of gif support only applies to 
> the use of LZW compression when writing a gif, so in general, read 
> support is not a problem. Also check out libungif
> http://sourceforge.net/projects/libungif
> which saves gifs w/o compression avoiding patent issues. Also 
> note that 
> the worldwide patent expires on July 7, 2004, so things might turn 
> around after then.
> 
> On Jun 25, 2004, at 12:57 PM, Kshitij Bedi wrote:
> 
> > Any Ideas on converting Gif to Png or Jpeg using PHP GD?
> > _______________________________________________
> > talk mailing list
> > talk at lists.nyphp.org
> > http://lists.nyphp.org/mailman/listinfo/talk
> 
> 
> Jeff Knight
> putamare not junk at putamare.net
> 
> _______________________________________________
> talk mailing list
> talk at lists.nyphp.org
> http://lists.nyphp.org/mailman/listinfo/talk
>