Simulate color blindness/defects?

Existing solutions and proposals for Inkscape:

a) Script extension:
Inkscape - Color Blindness Extension | kaioa.com:
<http://kaioa.com/taxonomy/term/33>

b) SVG filter effects:
Color Blindness filters - OpenClipArt:
<http://www.openclipart.org/detail/22299>

c) Display filters
Blueprint "Display filters"
<https://blueprints.launchpad.net/inkscape/+spec/display-filters>
<http://wiki.inkscape.org/wiki/index.php/SpecDisplayFilters>

d) New color tool
Blueprint "A Colorscheme designer for the Inkscape palette"
<https://blueprints.launchpad.net/inkscape/+spec/agave-integration-in-inkscape-bottom-palette>
Bug #641403 “Import Agave into the Inkscape GUI”

Making a tool or extension which would let you simulate different levels of colorblindness would be ideal, especially for the thousands of us scientists which use inkscape, since conveying properly messages through color-coded graphics is essential to sceintific production

We already have too many extensions IMHO, and an SVG filters version looks more promising. If it's only a matter of colormatrix values, it could be relatively easy to implement.

Patch attached. Tested on Windows XP with Inkscape trunk rev. 13979.

Some comments:

> a) Script extension

Unfortunately, the extension is based on a code that might not be compatible with the GPLv2 license:
-----
The used Color Blind Simulation algorithm is copyright (c) 2000-2001 by Matthew Wickline ( http://matthew.wickline.org/ ) and the Human-Computer Interaction Resource Network ( http://hcirn.com/ ). For commercial licenses [of the original JavaScript code or derivative works thereof], please contact the Human-Computer Interaction Resource Network ( http://hcirn.com/ ).
-----

> b) SVG filter effects

The attached patch uses the filters as defined in the SVG file. No license issue here (openclipart), seems faster than the Python extension, but the result it not as accurate (everything is calculated in the RGB colorspace).

Comments are very welcome.

Just a quick comment: (as a non color blind person) try to replicate the topmost figure on https://nl.wikipedia.org/wiki/Kleurenblindheid

(the figure caption says: bottom left: how a "red-colourblind" person sees the picture; bottom right: how a "green-colourblind" person sees the picture )

Attaching fixed version of patch (original one doesn't apply) as convenience for other testers.

Could inkscape use a tighter filter effects region FER (100% instead of 120% (default if not specified)) for such color effects?

> Attaching fixed version of patch

Thanks! I had to hand-edit the file and completely failed my copy-paste...

> Could inkscape use a tighter filter effects region FER

Of course yes.

Feature added in the trunk, revision 13984.
Please test!

Hishihara plates. Should help testing.