On 02.01.2014, at 15:14, Nicolas Cellier <nicolas.cellier.aka.nice at gmail.com> wrote:

> 
> 2014/1/1 Tobias Pape <Das.Linux at gmx.de>
> 
> On 01.01.2014, at 19:55, commits at source.squeak.org wrote:
> 
> > Nicolas Cellier uploaded a new version of Graphics to project The Inbox:
> > http://source.squeak.org/inbox/Graphics-nice.285.mcz
> >
> > ==================== Summary ====================
> >
> > Name: Graphics-nice.285
> > Author: nice
> > Time: 1 January 2014, 8:53:32.416 pm
> > UUID: 04aee02d-83ae-4b4d-aed9-968a6a7487db
> > Ancestors: Graphics-nice.284
> >
> > Change Color implementation from 10 bits per (rgb) component to 8 bits per component.
> > Several considerations motivate this change:
> > - no Graphic output is using 10 bits;
> 
> Au contraire!
> http://lmgtfy.com/?q=10+bit+graphics
> https://nvidia.custhelp.com/app/answers/detail/a_id/3011/~/10-bit-per-color-support-on-nvidia-geforce-gpus
> http://www.luminous-landscape.com/reviews/accessories/10bit.shtml
> http://www.amd.com/us/Documents/10-Bit.pdf
> 
> Best
>         -Tobias
> 
> Thanks for the links Tobias, that's interesting.
> Well, no graphics output in Squeak was what I meaned.
> Squeak is far from being able to exploit those 10 bits, because it would require
> - BitBlt support with a new format (30 bits depth)
> - per device gamma correction
> It's also unclear for me how the alpha channel is represented/processed (pre-processed?)

You need to use OpenGL anyway to create a 10 bit display surface. I think you will still get an 8 bit alpha channel if you request 10 bits each for r, g, and b. But a typical texture format would be RGB10_A2 (with just 2 bits of alpha). Refer for example to the AMD document Tobias googled.

It makes little sense to use 10 bit color for a regular bitblt-based UI, so that is no reason to object.

However, looking at Graphics-nice.285, the only method that gets simpler is asHTMLColor. So except for reducing the resolution by 8 bits, what benefit do we have? I thought the original reason was to get rid of TranslucentColor, but since that would result in more LargeInts you didn't do it, right? 

- Bert -

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