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RE: 3.7 DDC: Colors

From: Scheppe, Kai-Dietrich <k.scheppe@t-online.net>
Date: Thu, 3 Aug 2006 10:16:38 +0200
Message-ID: <398533C370C23441981074C456AA3BDDCED754@QEO00226.de.t-online.corp>
To: "Chris Lilley" <chris@w3.org>, "Susan Lesch" <lesch@w3.org>
Cc: <public-bpwg-comments@w3.org>

Hi Chris,

Thanks for the input.
As I read your message at the moment this is a lost cause :-)

What would be, in your opinion, a better way to express our intent? 
The intent is to give a minimum capability in color display that must be
fulfilled in order to have decent online experience.
Since there doesn't seem to be a generally understood, basic system, we
chose this to express that intent.

-- Kai

> -----Original Message-----
> From: public-bpwg-comments-request@w3.org 
> [mailto:public-bpwg-comments-request@w3.org] On Behalf Of Chris Lilley
> Sent: Wednesday, August 02, 2006 1:09 PM
> To: Susan Lesch
> Cc: public-bpwg-comments@w3.org
> Subject: Re: 3.7 DDC: Colors
> On Wednesday, August 2, 2006, 7:56:42 AM, Susan wrote:
> SL> Hello,
> SL> A comment for the MWBP guidelines 3.7 Default Delivery 
> Context [1]. 
> SL> Under Colors it says:
> SL>     "Web safe.
> SL>      (A Web safe color is one that has Red/Green/Blue components
> SL>      chosen only from the values 0, 51, 102, 153, 204, and 255.)"
> SL> The definition looks good
> I wouldn't call it "good", and the concept of 'web safe 
> colors' is based on a number of misunderstandings. 
> I'm frankly alarmed to see some piece of mythology like this 
> turning up in a W3C spec. Next we are going to be claiming 
> that using some magic set of colors always prevents 
> dithering, and such like nonsense.
> SL> but usage of the phrase "Web safe" doesn't always match the 
> SL> definition. Maybe the spec could say "216 colors" instead of Web 
> SL> safe (the 216 are the 6x6x6 cube that is part of some 
> popular 8-bit 
> SL> video palettes). Chris Lilley, copied on this mail, may 
> or may not 
> SL> have a moment to correct me there.
> Thanks, Susan.
> I do have a moment - both to correct the definition and to 
> argue that the term is a misnomer and is neither safe nor 
> useful for the Web. 
> Its easier to describe it in hex, rather than arbitrary 
> decimal numbers.
> A 6x6x6 simulation of truecolor is produced by using three 
> digit color values (eg #3CF )  where each digit is either 
> 0,3,6,9,C or F.
> There is no guarantee whatsoever that restricting colors in 
> an image to these values will prevent dithering, so the 
> 'safe' part of 'web safe' does not apply.
> Furthermore, restricting an image to these colors often means 
> that,on a limited palette system,the colors need to get 
> mapped to the closest color in the palette so the original 
> color is subject to two distortions one to move it to 'web 
> safe' and one to move it to the actual device palette. This 
> results in objectionable color shifts and banding which could 
> have been avoided. 
> 'Web safe' colors are an anachronism based on faulty logic. 
> They had some utility in the days of 8-bit Mac and PC 
> graphics, giving some chance that the colors would not 
> dither. However, they totally failed on other systems (eg 
> XWindows) where they would *always* dither. Their 
> applicability to mobile is highly questionable.
> SL> [1] http://www.w3.org/TR/2006/CR-mobile-bp-20060627/#ddc
> SL> Thank you,
> -- 
>  Chris Lilley                    mailto:chris@w3.org
>  Interaction Domain Leader
>  Co-Chair, W3C SVG Working Group
>  W3C Graphics Activity Lead
>  Co-Chair, W3C Hypertext CG
Received on Thursday, 3 August 2006 08:16:59 UTC

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