Thanks for the explanation and the solution !

However I suppose the kind of rendering artefacts seen on the joined png has been noticed a long time before. It occurs with every versions of Inkscape and at every render quality for blur and filters.

De : Niko Kiirala <niko@...1267...>
À :
Envoyé le : Mar 30 mars 2010, 17 h 34 min 37 s
Objet : Re: [Inkscape-devel] Filter effect and blur background

Tue, 30 Mar 2010 11:15:26 +0200
Yann Papouin <yann.papouin@...1063....> kirjoitti:

> On there is a
> note about this property
> "There's no GUI for setting the enable-background property. This
> property has to be set on some parent layer of filtered object to
> make Background Image and Background Alpha input images work."
> Does the background image support is implemented?  Do you think that
> the same effect can be achieved with filters by applying the effect
> on a shape (that will blur its background content)?

Seems you've received a couple responses already while I was writing
this. however, I'll explain the background here a bit.

The renderer does support background images and can do the effect you
are looking for. What that wiki page is trying to tell, the GUI is
somewhat incomplete. You'll need to use the XML editor to add the
enable-background:new property to a suitable layer or apply a
non-default layer blending mode (which will automatically add
enable-background:new to the root layer of the document)

Also, shamelessly promoting my own blog posts here ;)

I created my own version of this filter, too. For the enable-background
stuff, take a look at the layer1 in Inkscape XML editor. Anything
inside layer1 will now be able to access the background image - but
only inside layer1. If you were to place stuff in layer under layer1,
that wouldn't be counted as background for filtering purposes.

Niko Kiirala