[CREATE] [OpenRaster] Layer colorizing (and other non-separable blend modes)

[Andrew Chadwick]

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OpenRaster should be able to store layers which colorize or set the
lightness of underlying pixels. It's a commonly requested feature from
artists using MyPaint.

Given the active Editor's Draft from the W3C CSS-SVG Effects Task
Force which is up at

http://dvcs.w3.org/hg/FXTF/rawfile/tip/compositing/index.html

would anybody object to my adding the following composite-op values to
the OpenRaster Layers Stack specification[1] using the following new
bullet point:

"""
  * In addition, the following non-separable compositing operations
are defined in the (SVG, Canvas and CSS) _Compositing and Blending 1.0
Editor's Draft_[[link]]: svg:color | svg:luminosity | svg:hue |
svg:saturation.
"""

Of interest, they're the non-separable blend modes defined in the PDF
specification and also in the Cairo compositing operators docs[2].

There is sample code available at
https://gitorious.org/~achadwick/mypaint/achadwick-mypaint in the
branch "layer-colorize-2" which implements the Color and Luminosity
blend modes. I would like to push this branch to the MyPaint
development master reasonably soon.

Would the Krita and GIMP folks reading this be OK with the change
outlined above?



[1]
http://www.freedesktop.org/wiki/Specifications/OpenRaster/Draft/LayersStack
revision 3, dated 2012-03-28 20:41:47

[2] http://cairographics.org/operators/ , CAIRO_OPERATOR_HSL_COLOR and
CAIRO_OPERATOR_HSL_LUMINOSITY

- -- 
Andrew Chadwick
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