[CREATE] First early draft for the OpenRaster's layer stack

[Cyrille Berger]

> - "standard" : for the list of filters and the associated mathematics,
> see the relevant OpenRaster specification
>
> -"composite" : composite are filters which are a composition of a list
> of stantard filters, the name must be the name of a filter defined in
> the same file
>
> I don't quite understand the difference :(
standard are "individual filters" filters for 
instance "invert" "brightness/contrast" "blur" etc.
And "composite" are filters which are in fact a composition of other filters. 
For instance "blur and invert at the same time" In the following example, the 
layers stack are equivalent:
<image>
<stack>
<effect name="standard:invert" />
<effect name="standard:blur" />
<layer name="layer 1" />
</stack>
</image>

or

<image>
<stack>
<effect name="composite:blurinvert" />
<layer name="layer 1" />
</stack>
<compositefilter name="blurinvert" >
 <filter name="standard:blur" />
 <filter name="standard:invert" />
</compositefilter>
</image>




-- 
--- Cyrille Berger ---