[cairo] Linear colorspace not a good idea

Michael Sweet mike at easysw.com
Tue Mar 14 03:29:36 PST 2006

Bill Spitzak wrote:
> Although I wrote a lot of arguments in favor of using linear space (see
> http://mysite.verizon.net/spitzak/conversion/index.html), there are 
> serious problems with using this for GUI. I think Cairo has to do all 
> compositing in the device space (ie sRGB for most of the devices we are 
> interested in, but allow the backend to decide).
> First is that there is a huge supply of icons that have been designed to 
> be composited in sRGB space and will have bad edges otherwise when put 
> atop the background they are designed for.
> ...

Images either have an implied profile or an embedded profile, and that
profile must be used in order to get the proper output.

Apple's Quartz2D manages multiple colorspaces - this does introduce
some complexity and it is sometimes confusing for developers when
they draw RGB=255,0,0 and get a slightly different color on the
screen, but ultimately it results in consistent output that is
properly matched to the screen/surface you are drawing to.  IMHO,
*that* is the model Cairo needs to adopt - surfaces with attached
profiles which define the mapping from a linear RGB colorspace to/from
the surface.

Michael Sweet, Easy Software Products           mike at easysw dot com
Internet Printing and Publishing Software        http://www.easysw.com

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