[Netsurf-develop] Low image quality in 256 colours

John Duffell jwd104 at york.ac.uk
Fri Dec 26 19:51:14 GMT 2003


In message <Pine.LNX.4.44.0312261737240.30227-100000 at tarrant.ecs.soton.ac.uk>
          John-Mark Bell <jmb202 at ecs.soton.ac.uk> wrote:

> On Fri, 26 Dec 2003, John Duffell wrote:
> 
> > Hi, something you may be interested to know.
> > 
> > Image quality is rather poor in 256 colour modes. wheras it's alright on
> > oregano, for example.  However, I wopuld agree that oregano is slower at
> > rendering.
> 
> Yep. This needs looking at. TBH, only the gif renderer is anywhere near 
> finished (although it doesn't do animated gifs yet). The jpeg renderer 
> uses the OS's inbuilt renderer (which is rather old and can't cope with 
> many images).

The Select image renderer seems quite good though, if I set it to quality 3
with the built in viewer the quality is as good as oregano, at quality 2 it's
as bad as netsurf.

It would be nice for it to use the built in ImageFileConvert for most things
but I would see the logic behind using optimised renderers for gif/jpeg and
perhaps png.  These could use some clever rendering algorithm to only render
parts of the images visible but cache them to allow smooth scrolling of the
page.  Of course increasing your font cache also helps ;)

> The png renderer is incomplete.
> 
> So it isn't really a surprise that image quality is poor. Does this happen 
> for gifs as well?

GIFs look ok, although there's a bit of thinking time before it appears. 
I presume one of the things going to be added would be rendinging images as
they arrive.

> If so, there's obviously something wrong in all the  image loading modules.
> If not, then I'm inclined to blame the  incompleteness of the code ;)

Yeah, well I can blame that :)

Thanks,
-- 
John Duffell
http://www.duffell.riscos.me.uk/




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