W3C home > Mailing lists > Public > www-style@w3.org > August 2008

Re: Color Lightening and Darkening

From: James Elmore <James.Elmore@cox.net>
Date: Thu, 28 Aug 2008 10:30:33 -0700
Message-Id: <11A4A3DD-8594-45FD-B682-EEB855C136B2@cox.net>
Cc: CSS <www-style@w3.org>, w3c-css-wg@w3.org
To: Daniel Glazman <daniel.glazman@disruptive-innovations.com>


On Aug 28, 2008, at 10:05 AM, Daniel Glazman wrote:

>
> Dave Artz wrote:
>
>> Can we get a second opinion 6 years later?  If a script kid can do  
>> it in PHP...
>
> I am no color expert and I am ready to read pros and cons here.
>
> </Daniel>
>
>

I am no expert, either, but I can see a few problems. First, and  
hardest, is that color is not a simple linear progression. Should  
lighter be linear or geometric, or should it be something else, which  
more closely matches the human perception; and what about filters and  
gamma corrections on output: will those be taken into account as  
well? And, what about the different colors (RGB)? If all three colors  
are the same intensity (#888888, for example) then it is fairly  
simple to lighten or darken the colors by changing them all the same  
amount. But what if they are different (e.g., #4488CC)? should all be  
adjusted the same amount? (To #2266AA? Or #3377BB? Probably not.) Or  
should they be adjusted some proportional way (e.g. 25%, giving  
#336699)? And, if we agree on how to lighten a color, what do we say  
to the next person, who asks CSS to lighten JUST THE RED? (or Green?  
or Blue?)

There is disagreement on what bolder and lighter mean for text, and  
now the group may try and agree on what lighter/darker means for  
colors. It seems to me that SVG has some experience with lighter  
colors, perhaps someone from that group could inform this group what  
they tried and how it worked.

This is not to say that I disagree with the request. Conceptually,  
lighter and darker for colors and for text are similar. In reality  
they are different. If there is a good solution, I would like to be  
able to use it.

(Wrote some more and deleted it. It sounded like I was insulting  
everyone.) Let me just say that this is a hard problem.


</James>
Received on Thursday, 28 August 2008 17:31:26 GMT

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