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Re: [css3-images] Gradients feedback

From: Alan Gresley <alan@css-class.com>
Date: Mon, 30 Aug 2010 14:46:35 +1000
Message-ID: <4C7B37AB.9050505@css-class.com>
To: fantasai <fantasai.lists@inkedblade.net>
CC: "Tab Atkins Jr." <jackalmage@gmail.com>, Boris Zbarsky <bzbarsky@mit.edu>, www-style list <www-style@w3.org>
Alan Gresley wrote:
> fantasai wrote:
>> On 08/29/2010 01:20 PM, Tab Atkins Jr. wrote:
>>> On Sun, Aug 29, 2010 at 11:12 AM, Boris Zbarsky<bzbarsky@mit.edu>  
>>> wrote:
>>>
>>>> [1] More precisely, in non-premultiplied space the point |t| between
>>>> rgba(r1, g1, b1, a1) and rgba(r2, g2, b2, a2), where 0<= t<= 1 is:
>>>>
>>>>  ...(a consequence of all such colors being equal to each other 
>>>> numerically
>>>> in premultiplied space).
>>>
>>> Yeah, color math goes over my head.  I'll just nod.
>>
>> I'm not even looking at the math here, but if bz's example is useful,
>> I suggest putting it in the spec as an example.
>>
>> ~fantasai
> 
> 
> There is a precise maths in color.
> 
> 
> <http://css-class.com/test/css/colors/3d-color-prism-216-colors.htm>
> 
> 
> The grayish band in the middle of the gradient is roughly the same as 
> the midway point between yellow and white / black in the 3d-color-prism. 
> It would actually be half the value in intensity. As seen in this the 
> 3d-color-prism, it is only the colors between yellow red and white/black 
> that get dirty. A gradient between orange and transparent would have a 
> brownish color in the middle.


Follow up.

<http://css-class.com/test/css/colors/gradient1.htm>


Note the brown midway between Orange and Transparent. This brown 
decreases somewhat if the background color is difference.

This next test shows what happens with color (full value to 
transparent) when there are steps between white and black in the 
background (this test has links to change the background, excuse the 
primitive of method). Note how the colors seem more intense as the 
background get darker.

<http://css-class.com/test/css/colors/gradient2.htm>


In saying this, there can be no true precise color because since we 
have 'trichromatic color vision' then one perception of a color 
changes depending on what other colors are around.



1. <http://en.wikipedia.org/wiki/Trichromatic_color_vision>



-- 
Alan http://css-class.com/

Armies Cannot Stop An Idea Whose Time Has Come. - Victor Hugo
Received on Monday, 30 August 2010 04:47:09 GMT

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