On Sunday 06 August 2006 16:00, Simone Giannecchini wrote:
> I fully agree with Andrea, we have been playing around the all week
> with different writers and the conclusion is that if you want to speed
> up things you need to use gif or png with indexed color model, if you
> want to dramatically speed up thing you need to used natively in the
> streaming renderer image with an index color model instead or drawing
> true color rgb and then reducing.
> What I am going to do next days is enabling the streaming renderer to
> use directly indexed buffered image with a standard prefixed palette
> of 256 color enabling that for GIF and paletted PNG and TIFF.
>
> Next step, as Andrea pointed out, would be investigating some sort of
> customization of palettes for optimal quality. The options we have
> right now on the plate are as he described, let's see if someone has
> some others bright ideas for step 2 (that is, after the standard
> palette work fine).
that's great guys, it was just the idea i had but still  hadn't the time to 
accomplish.
Wouldn't it be possible, instead of using a fixed pallete, to create it at 
runtime by inspecting the colors needed by the SLD object?

2c-

Gabriel.
>
>
>
> Simone.
>
> On 8/6/06, Andrea Aime <[EMAIL PROTECTED]> wrote:
> > Hi all,
> > during the last week I spent some time trying to get the best possible
> > performance out of GIF WMS serving.
> >
> > Now, during my tests I noticed that GIF encoding took as much time
> > as pure rendering, if not more. One way to speed encoding up in a
> > dramatic way (5/10 times faster) is to render stuff directly on a
> > 256 colors palette, something that you can get by creating a
> > buffered image with the TYPE_BYTE_INDEXED flag.
> >
> > The drawback about this approach is that the TYPE_BYTE_INDEXED
> > provides you with a fixed 256 colors palette. Now, thinking about
> > this, it's not such a great problem if we allow the user to create its
> > own palette, or give him some tools to estimate a good one.
> >
> > It would not be so difficult: take the map you want
> > to render, with all of the layers enabled, and render it into true
> > colors. Then perform a reduction to 256 colors -> the palette you get is
> > a stable palette and it's a good estimate of the one you need.
> > Of course this would be only a tool for estimation, leaving the user
> > free to perform the estimation in another way (for example, we could
> > learn to import paint shop pro/gimp palettes).
> >
> > I haven't tried, but hope the same would apply to PNG images as well
> > (with various palettes, ranging from 256 to 65xxx colors).
> > Me or Simone are going to try this out on the coverage branch next week.
> >
> > Cheers
> > Andrea
> >
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-- 
Gabriel Roldán ([EMAIL PROTECTED])
Axios Engineering (http://www.axios.es)
Tel. +34 944 41 63 84
Fax. +34 944 41 64 90

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