Re: [filter-effects] feBlend filter (was: Re: [css-filters] feBlend filter)

On Wed, May 29, 2013 at 8:35 PM, Dirk Schulze <dschulze@adobe.com> wrote:

>
> On May 29, 2013, at 7:41 PM, Rik Cabanier <cabanier@gmail.com> wrote:
>
> >
> >
> > On Wed, May 29, 2013 at 7:14 PM, Dirk Schulze <dschulze@adobe.com>
> wrote:
> >
> > On May 29, 2013, at 6:59 PM, Rik Cabanier <cabanier@gmail.com> wrote:
> >
> > >
> > >
> > > On Wed, May 29, 2013 at 5:33 PM, Dirk Schulze <dschulze@adobe.com>
> wrote:
> > >
> > > On May 29, 2013, at 5:05 PM, Rik Cabanier <cabanier@gmail.com> wrote:
> > >
> > > [snip]
> > > > If we replace the formulas with the one without compositing, what
> would it mean for blending two intermediate results?
> > > > The result would exclude compositing completely. It is unclear how
> this can be done.
> > > >
> > > > You'd have to explicitly call feComposite on the blended result.
> > >
> > > feComposite uses the alpha channel of the two input primitives.
> feBlend the same, just that you loose the alpha channel on the result of
> your feBlend (since the state is unclear).
> > >
> > > Why would you lose the alpha channel? Blending doesn't affect source
> alpha (ár = ás)
> > >
> > > If the next primitive after feBlend is feGaussianBlur, what would be
> blurred on the alpha channel? I do not think that you can easily separate
> blending from compositing inside a SVG filter tree.
> > >
> > > Sure you can. feGaussianBlur would work the same except that the
> source colors are now blended and alpha is unaffected.
> >
> > If ar = as, why would the alpha channel would not be affected on
> blurring?
> >
> > If you do a gaussianBlur, its input regardless of it's blended or not,
> will always have the same alpha values.
> > A good question is if blurring after blending makes sense of course :-)
>
> You blur all channels, including the alpha channel for feGaussianBlur.
> Since you say ar = as, this basically means source-in, doesn't it?
>

I'm unsure what you mean.
Blending changes the color, but leaves the alpha. This result is fed into
feGaussianBlur which will change the colors and the alpha. There's no
'compositing' happening...

Received on Thursday, 30 May 2013 04:22:34 UTC