[cairo] Subtractive API, part 0

ecir hana ecir.hana at gmail.com
Sat Jan 30 12:46:26 PST 2010

On Sat, Jan 30, 2010 at 12:59 PM, Jon Cruz <jon at joncruz.org> wrote:

> You insist that what you want has nothing to do with display. However, it *does* seem to deal with color, since that is the general purpose of Cairo. A color is a sensation of perception. Without enough details to be able to *display* something, it's not really colors you are working with, just random numbers...

I'm afraid you misunderstood what I wrote. What I said was that the
numbers should be arbitrary from the Cairo's point of view. Your
application could supply any RGB for displaying you want, be it
managed or not. What I said was, that it should be the application who
keeps track of all the properties to make CMS work. The application
would do the color conversion (possible with the use of other library)
and supply the calibrated values straight to Cairo. I fail to see how
this prevent a color to show up on screen in the way you want..?

> Color management of *some* sort is required. For many situations, however, the W3C was able to solve the need by simply stating "all RGB values are in the sRGB colorspace". No need for conversions, libraries, etc. A simple change in documentation was sufficient in many areas. If things stay there, then nothing further has to be done. However, if one needs to go in and out of things, then things should be converted in a predictable manner. There are simple ways that Cairo can be updated to handle more than RGB. However, if broken shortcuts are taken, then implementers, maintainers and users of Cairo will have to suffer with any poor decisions for quite some time to come. I'm fairly certain we all just want to find a minimal solution that will be sufficient. But again, I'm pretty sure that "let me throw random numbers in, and I don't care what comes out days or weeks later" is a route that is best to be avoided.

Ok, I think we more or less agree. CMS - ok, why not. But do you think
it should be part of Cairo or it should be separated? Whether RGB
should be default in sRGB, I don't know, I don't have an opinion on
that one. Or maybe I have a tiny one - it feels a bit uncomfortable to
me to hardcode a certain color space to Cairo... How does it play with
the rest of Cairo? Is it ok just to say that from now one all the RGB
values mean sRGB? As I said, this is not the topic for the proposal -
we don't even know how to define a golden color, yet. Perhaps you
could start a separate thread about sRGB support? And what do you mean
by "converting in predictable manner"? Could you give an example?

"we all just want to find a minimal solution that will be sufficient"
- very well.

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