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Re: Some comments on <image>

From: ddailey <ddailey@zoominternet.net>
Date: Sun, 19 Sep 2010 19:46:42 -0400
Message-ID: <597210E6BC79411BA224001830D4969E@disxgdg31szkx7>
To: "Jeff Schiller" <codedread@gmail.com>, <anthony.grasso@cisra.canon.com.au>
Cc: "David Woolley" <forums@david-woolley.me.uk>, <www-svg@w3.org>
All five of the major released browsers (ASV, FF, Opera, Chrome and Safari) support GIF in SVG. I don't know about IE9 or mobile platforms.

D
  ----- Original Message ----- 
  From: Jeff Schiller 
  To: anthony.grasso@cisra.canon.com.au 
  Cc: David Woolley ; ddailey ; www-svg@w3.org 
  Sent: Sunday, September 19, 2010 7:18 PM
  Subject: Re: Some comments on <image>


  Out of curiosity - is there any browser that doesn't actually support GIF files in svg:image ?  I'd be surprised...

  Jeff


  On Sun, Sep 19, 2010 at 4:10 PM, Anthony Grasso <anthony.grasso@cisra.canon.com.au> wrote:



    On 20/09/2010 4:22 AM, David Woolley wrote:

      ddailey wrote:


        1. The spec says "Conforming SVG viewers need to support at least PNG, JPEG
        and SVG format files." Why not GIF? I recall a profound nervousness


      I think the basic reason is that PNG can exactly represent any image that GIF
      can represent, except for animations, and usually does so more compactly for
      equal quality, but also has the option of better quality.




    In saying that, there is nothing stopping an SVG viewer/editor (to my knowledge) from supporting GIF in addition to JPEG and PNG. :)



        that spread like squid ink through the open source community [1] 10 or 12
        years ago as the holders of the GIF patent threatened to go after those who
        used it without license. I believe, however, that the patent has since
        expired. [2] A search of gif in Google images shows about a billion files with
        close to half that number for PNG. In many cases GIF


      Image formats are often chosen without any real understanding. There are an
      awful lot JPEG images (or PDF images using DCT) that are totally unsuitable for
      JPEG, either because people believe it produces the best compression for
      everything (and only make one dimensional decisions), or because they don't know
      PNG and paintbrush produces very poor GIFs.


        files are smaller than PNG files, I think, and lots of the older public


      Although it is possible, and may be more common for very small images, the
      compression scheme used in PNG is generally better than that used in GIF (the
      LZW used in GIF, and the actual subject of the patent, is designed as a
      compromise between compression speed and and compression ratio - it was really
      intended for real time compression of streamed data. That in PNG is designed to
      give good compression, at the expense of slow compression speeds.

      Apart from the possibility that PNG may have a higher overhead, the other reason
      that you may observe this is that PNG has more possible formats, and, for
      example, paintbrush uses 24 bit unpalletised for PNG and uses a non-optimised
      palette for GIF.


        domain imagery sites on the web used gif because, well, PNG wasn't available
        then. All the browsers I know of go ahead and support GIF anyhow, but it is
        one thing we can be certain of that no longer has patent entanglements. PNG??
        Who can ever be completely sure until the 20 years pass?


      It's very likely that any such patent would also affect GIF.
Received on Sunday, 19 September 2010 23:47:14 GMT

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