[webkit-dev] WebKit runtime image compression

[Antti Koivisto]

On Sun, Dec 14, 2008 at 9:12 AM, Paul Pedriana <ppedriana at gmail.com> wrote:

> For a lot of web pages, images are the primary source of memory usage.
> These images seem to be typically stored as RGB or ARGB data in the
> BitmapImage class. It seems to me that applications that wish or need to
> save runtime memory could benefit from runtime image compression whereby
> images are stored in some compressed form instead of RGB or ARGB formats. I
> am currently looking into this possibility and I'm wondering if anybody has
> previously looked into it.
>
> My current idea is to support two kinds of compressed images: RLE and
> YCoCg-DXT5. The former could be for any images that are simple enough, and
> the latter could be for general images and give a fixed 4:1 compression
> ratio. RGB transforms to YCoCg with better decorrelation (breakdown of RGB
> to YCC) than YCbCr and many images can get PSNR values over 40 (i.e. hard to
> tell from original). If the computer has decent vector processing or a
> programmable GPU, the performance could be decent, otherwise it depends on
> the CPU. (A)RGB could of course remain as a fallback.
>
> I'm wondering if anybody has looked into runtime image compression with
> WebKit and considered options such as this.


Several ports (S60 and Android I think) RLE compress suitable bitmaps. It
does not need WebKit level support.


   antti


>
>
> Thanks.
>
>
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