W3C home > Mailing lists > Public > www-svg@w3.org > September 2010

Re: Some comments on <image>

From: Jeff Schiller <codedread@gmail.com>
Date: Sun, 19 Sep 2010 16:18:19 -0700
Message-ID: <AANLkTinFznROjH45UUZZ4cC_GXuqWcdiWmcO-pT0QLFq@mail.gmail.com>
To: anthony.grasso@cisra.canon.com.au
Cc: David Woolley <forums@david-woolley.me.uk>, ddailey <ddailey@zoominternet.net>, www-svg@w3.org
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 23:19:07 GMT

This archive was generated by hypermail 2.3.1 : Friday, 8 March 2013 15:54:46 GMT