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Re: [css4-color] Make the r/g/b components be <number> rather than <integer>?

From: Boris Zbarsky <bzbarsky@MIT.EDU>
Date: Sat, 09 Jun 2012 01:24:03 -0400
Message-ID: <4FD2DDF3.6000408@mit.edu>
To: www-style@w3.org
On 6/9/12 12:59 AM, Brad Kemper wrote:
> RGB values can be negative?

Last paragraph of 
http://www.w3.org/TR/CSS21/syndata.html#value-def-color says:

   Other devices, such as printers, have different gamuts than sRGB;
   some colors outside the 0..255 sRGB range will be representable
   (inside the device gamut), while other colors inside the 0..255 sRGB
   range will be outside the device gamut and will thus be mapped.

and then there is a nice note:

   Note. Mapping or clipping of color values should be done to the
   actual device gamut if known (which may be larger or smaller than
   0..255).

> Isn't zero the absence of any light from that component of the pixel?

You just assumed that your CSS styled document is being shown using "light".

> Do negative values suck the light from other light sources in the room?

Negative values correspond to a subset of the colors you can get our of 
your printer that your computer screen can't show.

-Boris
Received on Saturday, 9 June 2012 05:24:33 GMT

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