[cairo] Color Filter for ColorBlind

Peter Clifton pcjc2 at cam.ac.uk
Thu Oct 22 05:58:20 PDT 2009

On Thu, 2009-10-22 at 10:59 +0100, Øyvind Kolås wrote:
> On Wed, Oct 21, 2009 at 5:23 AM, Tiago Rezende Campos Falcao
> <tiagofalcao at gmail.com> wrote:
> > First, I would like to introduce myself.  I am a student at a Brazilian
> > University (Unicamp), attending a graduation course entitled "Communitary
> > Informatics".  Me and other 2 fellows are interested in contributing with
> > GCompris, but we can apply the fix filter in lower layer like Cairo to give
> > this option to all cairo based programs.
> > We would like to know from you if we can try do this and if it is
> > interesting for Cairo Community.
> What type of "color filter for color blind" are we talking about here?
> One useful for Color Blind people or developers/designers taking such
> users into account?
> Simulating color deficient vision is simpler than augmenting a color
> image with extra contrast helping a color blind person perceive
> differences that otherwise would not be perceived.
> Simulating color blindness by simply changing individual colors is
> useful for designers/developers to understand how different color
> deficiencies cause an interface to be perceived and address problems
> and can be implemented as a point-filter. I believe a proper filter to
> add back the spatial contrast lost by observers with deficient color
> vision needs to be a spatial filter (like a blur) on the final UI.
> I do believe that both kinds of such filters belong either in the
> application(s) themselves or in the window manager/windowing system
> along other forms of color profiles.

Just a quick note, that if you are using compiz, then you will already
have the feature you need in its accessibility section. I believe it
uses an OpenGL pixel shader (or some other OpenGL-fu) to implement the
filter very efficiently. (I can watch full-screen videos with the filter
enabled with no notable CPU penalty).


Peter Clifton

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