[whatwg] Colour correction (was: Canvas ImageData comments)

[Henri Sivonen]

On Jan 21, 2008, at 01:36, Maciej Stachowiak wrote:

> On Jan 20, 2008, at 11:03 AM, Henri Sivonen wrote:
>
>> On Jan 20, 2008, at 19:58, Darin Adler wrote:
>>> I think the sRGB design is a good one.
>>
>> I disagree. Why would you want a brand new Cinema display emulate  
>> the gamut of an office CRT from the previous millennium potentially  
>> by clipping instead of stretching the colors to gamut of the device  
>> at hand?
>
> Wouldn't changing the default gamma have essentially the same effect  
> (with the added difference that even profile-tagged images could not  
> take advantage of wider gamut)?

Gamma correction maps the [0.0, 1.0] range to [0.0, 1.0], so it  
doesn't make the available range of color narrower or wider--it just  
affects the spacing of the available values within the range. If  
compatibility considerations were absent, the Mac default gamma would  
have merit, since it gives the light color range more precision  
whereas the TV/Windows legacy gamma wastes precision in the dark  
range. However, if the common case (the Web) lives in sRGB, which  
isn't the Mac native gamma, doing the color space conversion not only  
takes away the supposed benefit of the Mac default gamma *and* adds  
the loss of precision caused by the inevitable rounding in the  
conversion.

-- 
Henri Sivonen
hsivonen at iki.fi
http://hsivonen.iki.fi/