Colour palettes with meaning (Was: Motivation for having a 'text color' that is invisible)

[christian ridderstrom gmail com]

On Sun, 28 Oct 2007, Lars Clausen wrote:

> For clarity, then: "transparent" means a color setting, while 
> "undisplayed" means that the (part of the) object is not considered to 
> exist for any calculations at all, including bounding box, diagram 
> extends, parenting etc.

While reading this thread, I had a partially related thought.

If there is a 'transparent' colour, or perhaps rather an 'alpha' channel, 
then I think it'd be good to be able to specify this using a symbolic 
reference rather than a number. I'm probably being unclear right now, so 
let me expand on the subject.

Generally speaking for colours, I would like to be able to specify a 
colour, e.g. "red-1" and the let several objects be "red-1". Once I change 
the definition of "red-1", I'd like the appearance of all object with this 
colour to also change. This is in contrast to having to go to every object 
and manually change the colour.

How is the above related to transparancy?  Well, if this can be done in 
degrees, we are really talking about an alpha channel (at least I think 
this is what it's called). With 50% transparancy, we will still have some 
colours in the object, and thus the R, G, and B channels are combined with 
an alpha channel that is 50%.  Now, instead of just adding a fourth value 
for the alpha channel, I think it'd be much better to be able to name 
certain colours (perhaps also being able to add a comment/description), 
and then refer to these.  This named colour would then in addition to the 
RGB values also have an alpha channel, i.e. a level of transparancy.

I hope this makes sense.
/Christian

--
Christian Ridderström, +46-8-768 39 44               http://www.md.kth.se/~chr