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Re: [Public WebGL] Gamma correction and texImage2D/texSubImage2D



Oliver Hunt wrote:
> The way browsers currently handle colour space is fairly simple, the
> actual format does not matter:
>
>   * The image includes a colour profile: then use that colour profile
>   * The image does not include a colour profile: then assume the image
> is in sRGB
>
> This is the model that WebGL texture loading should follow in order to
> be consistent with other web content.
>
> Obviously WebGL will need an API to load raw (un "corrected") data
> into a texture in order to handle a few use cases, but other than that
> additional API there shouldn't be any other logic necessary.
>
> Basically the complete (image to display) model is:
>
>             Image                       WebGL Context                
>       Display
>   <arbitrary colour space>  -> match ->   Linear RGB   -> match ->  
> <arbitrary colour space>
>
> With an option to do
>             Image                       WebGL Context                
>       Display
>   <arbitrary colour space>  ->  nop  ->   Linear RGB   -> match ->  
> <arbitrary colour space>
>
> The actual file formats, and the actual mechanism of matching isn't
> relevant, all that we need to do is guarantee the colour space of the
> GL context.
>
> --Oliver
Yes - that's workable.

I'm a little concerned about the meaning of if the "image does not
include a color profile: then assume the image is in sRGB"...that's
going to cause a bunch of grief to people who don't have an advanced
degree in specification-parsing.   But so long as we can override the
Image=>WebGL conversion painlessly, I'll just do that unconditionally
and all will be well.

The critical parts are that we assume that the WebGL context is ALWAYS a
linear color space (because that's all our hardware will ever be) - and
that (as a consequence) something after that in the pipeline applies a
decent gamma value...which would most efficiently be a GPU-based
compositing step.

Great!

  -- Steve

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