Blend Modes

[Bug Importer]

Different blend modes (screen, lighten only, overlay,
etc) as in the GIMP would be useful. I use that feature
frequently. It could be used to create effects as
illustrated in the tutorial at:

http://www.ndesign-studio.com/resources/tutorials/glassy_button.htm

Al,
San Jose

[Daniel Pope (djpope)]

The effect given in the tutorial you linked can be easily
achieved with alpha composition. However, it is true that
not all effects can be achieved without compositing options
(eg. lens flare requires "lighten").

SVG 1.1 only provides alpha-channel compositing:

http://www.w3.org/TR/SVG11/masking.html#SimpleAlphaBlending

SVG 1.2 will provide this stuff with the comp-op property.

[Niko Kiirala (kiirala)]

Originator: NO

While there are plans for blending modes for SVG 1.2, some of them can
already be accomplished by using filter effects. There are some caveats
with semi-transparent backgrounds, though.

Blending with filter effects is implemented in current SVN head, with an
UI to select the blending mode, so I'd say this request is implemented.

[Antonio Roberts (hellocatfood)]

Is it possible to have more blend modes? Currently there's four available whilst GIMP has 21

[ScislaC (scislac)]

Antonio,
Unlike gimp, we are limited by the SVG specification. If there are only 5 blend modes specified by the w3, that is all we can implement.

[Pablo Trabajos (pajarico)]

ScislaC, yes, but maybe other modes can be implemented with a combination of filters? I'm not a filter guru...

[naught101 (naught101)]

ScislaC: There's a number of other features that inkscape has implemented that aren't in the SVG spec... maybe things like this should be implemented in order to improve the SVG spec on the next version?

[Pablo Trabajos (pajarico)]

naught101: there are two ways to get out of the SVG spec:
A) by implementing new stuff that's still backwards compatible with the SVG spec. Example: path effects, where the effect attributes are stored for Inkscape to use while producing a perfectly viewable file for other standard SVG viewers.
B) by implementing new stuff that's is outside of specs and there is no way (or not an easy one) to make it compatible with standard SVG viewers. Example: the proposition of conical gradients that is laying somewhere in this bug tracker.

I think that Inkscape has used A several times but B is completely NOT encouraged for it would be against the SVG spec, which is one of the main targets of the software.