W3C home > Mailing lists > Public > www-svg@w3.org > April 1999

Re: Request for information.

From: Chris Lilley <chris@w3.org>
Date: Sun, 04 Apr 1999 18:37:29 +0200
Message-ID: <37079549.1B0E8B43@w3.org>
To: MWhisman@aol.com
CC: www-svg@w3.org


MWhisman@aol.com wrote:
> 
> maggieomally@sprint.ca
> wrote asking about color codes.

> Red, Lime, Blue, Aqua, Fuchsia, Yellow
> Maroon, Green, Navy, Teal, Purple, Olive
> Black, Gray, Silver, White
> 
> There are other color names defined, but they are non-standard, so you're
> better off using the standard names or the standard numeric method below.

Yes.

> You can also specify colors as hexadecimal sRGB values. For example, here is a
> light blue: #99CCFF, and here is a rusty brown: #993300.

Note that these can be expressed more compactly as #9CF and #930
respectively.

> Browser- or "web-safe" colors are colors that any web browser 

Correction - any Web browser which always uses either the MacOS or
Windows system palette, has a 256 color mode, is not using a 16 color
mode and is not using a 15bit, 16bit or 24bit color mode, and never
tries to redefine the palete to an optimal or non-default one.

> can view non-
> dithered (solid) regardless of their graphics system's color depth. 

Unless that depth is 16 (4bits). Or 128 (7bits) etc.

> Use values
> 00, 33, 66, 99, CC, and FF in your colors and they'll be safe. You can define
> any RGB color, such as #ABCDEF, but they may appear dithered (speckled) to
> visitors with poor graphics capabilities.

Otherwise, correct. If someone still believes in the convenient fiction
of browser safe colors and would like to cater for folks who think that
256 color modes are suitable for multimedia systems[1], then CSS does
actually make it easy for you.

Just use any three-digit color where the digits arte taken from the list
0,3,6,9,C,F

> Sorry, no way of defining in CMYK, if you're familiar with that.

That is a feature not a bug, which I can expand on in mind-numbing
detail if you really want.

However, if you want to specify a particular color in CSS (and thus, in
SVG), have your color management system convert it from whatever color
space it is in to sRGB, and express it in decimal percentage notation so
that you can get component values less than zero and greater than 100%.

This gives you the ability to specify any visible color,  even those
which are way outside the gamut of any monitor or printer. The closest
displayable color which is within gamut will be used.

[1] have you ever seen a new computer for sale in the last three years
which has a highest available color resolution on 256 colors indexed?
No, not have I. Ever sincde 2Mb of video memory became a trifling and
inconsequential amount, rather than the stuff of dreams (I believe this
happened areound 1995), 256 colors as a design medium became quaint and
obselete.

--
Chris
Received on Sunday, 4 April 1999 12:39:57 GMT

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