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Re: [Public WebGL] The Newly Expanded Color Space Issue



On Sep 6, 2010, at 1:43 PM, stephen white wrote:

> On 07/09/2010, at 3:36 AM, Chris Marrin wrote:
>> states that "All RGB colors are specified in the sRGB color space". Since CSS colors are sRGB, it follows that the Canvas should be sRGB.
>> OpenGL assumes framebuffer color components are stored in a linear color space". So since OpenGL uses linear it follows that the WebGL Canvas should be linear.
> 
> Perhaps we're missing a point here... the colour of the pixels are in sRGB, while the values of the pixels are linear. Two different things.

I don't understand this distinction at all, and perhaps this is my problem! 

A pixel value of 128,128,128 in the drawing buffer will give me a particular shade of grey when displayed on a monitor. If the compositor considers it to be a linear buffer, it will perform color correction that will cause that pixel to appear 50% grey. If it considers the drawing buffer to be sRGB, it will perform color correction (or maybe none will be needed) to make that pixel look darker than that (according to the sRGB gamma).

So if I consider my drawing buffer to be sRGB, I would need a value greater than 128,128,128 to get a display of 50% grey. That gives you a greater range of dark colors, which I believe is Thatcher's argument. But figuring out what pixel value to use to get 50% grey requires extra computations, which I believe is Steve's argument. 

Is there more to it than that?

-----
~Chris
cmarrin@apple.com




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