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Re: [css3-images] Proposed Gradients changes

From: Alan Gresley <alan@css-class.com>
Date: Wed, 24 Nov 2010 11:41:29 +1100
Message-ID: <4CEC5F39.50509@css-class.com>
To: "Tab Atkins Jr." <jackalmage@gmail.com>
CC: Chris Lilley <chris@w3.org>, Anne van Kesteren <annevk@opera.com>, Brad Kemper <brad.kemper@gmail.com>, www-style list <www-style@w3.org>
On 24/11/2010 7:53 AM, Tab Atkins Jr. wrote:
> On Tue, Nov 23, 2010 at 11:54 AM, Chris Lilley<chris@w3.org>  wrote:
[snip]
>> TAJ>  (going from yellow to transparent in premultiplied colors is
>> basically TAJ>  equivalent to going from yellow;opacity:1 to
>> yellow;opacity:0 in SVG, TAJ>  modulo possibly some precision loss
>> in the CSS colors).
>>
>> Yes. The precision loss is a real concern there; at opacity 0.5
>> (1/2) you have gone from 8 bits per component to 7; at opacity
>> (1/16) you are down to 4 bits per component (only 16 distinct
>> shades of red, green and blue). This causes hue shifts due to
>> quantisation error.
>
> Right, but isn't that shift too minor to care about in basically all
> cases, since lower opacity means you're contributing less color
> information in the first place?

This may be true for current display devices that shows a sRGB gamut but 
some display devices now can show scRGB. Also future displace devices 
may have much better gamma correction.

I would like to ask you a simple question. At what point does the below 
gradient use imaginary colors of scRGB gamut?

background: linear-gradient(left, rgba(-20, 270, 250), transparent);

Or at what point along the gradient does it become transparent?


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

Armies Cannot Stop An Idea Whose Time Has Come. - Victor Hugo
Received on Wednesday, 24 November 2010 00:42:12 GMT

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