W3C home > Mailing lists > Public > www-svg@w3.org > July 2012

Re: mask: luminance or alpha

From: Rik Cabanier <cabanier@gmail.com>
Date: Mon, 30 Jul 2012 21:06:57 -0700
Message-ID: <CAGN7qDCrorVP+SYUbhad_2bK+Cd+A=3mzrm7N0MJyyQ4e9ziLw@mail.gmail.com>
To: Dirk Schulze <dschulze@adobe.com>
Cc: Rik Cabanier <cabanier@adobe.com>, "Tab Atkins Jr." <jackalmage@gmail.com>, "www-svg@w3.org" <www-svg@w3.org>
On Mon, Jul 30, 2012 at 8:20 PM, Dirk Schulze <dschulze@adobe.com> wrote:

>
> On Jul 30, 2012, at 8:02 PM, Rik Cabanier <cabanier@gmail.com> wrote:
>
> > On Mon, Jul 30, 2012 at 7:51 PM, Dirk Schulze <dschulze@adobe.com>
> wrote:
> >
> > On Jul 30, 2012, at 7:31 PM, Rik Cabanier <cabanier@gmail.com> wrote:
> >
> > > Any vector artwork created from any Adobe application, InkScape,
> CorelDraw and XAML.
> > No, I meant content. All these products can create alpha masks as well.
> That doesn't count, otherwise I could say 99.99% of the vector artwork use
> alpha masking :).
> >
> > I'm not talking about the products, but what they create.
> > My original 99.99% was for SVG/PDF content, but I think it applies to
> other vector content as well (Flash excluded).
> I am just saying that this is not an argument. And when a platform just
> supports one possibility but not the other, then of course you just find
> content with that technology - everything else would be stupid. So your
> number of 99.99% doesn't help at all. And again to "what they create": all
> these tools can create alpha masks as well.
>

PDF1.4 and up and SVG have support for both.
I can assure you that Adobe vector applications never create alpha masks;
it's always luminosity. I can do a query on our internal PDF database to
see if there are any PDFs with alpha mask

I don't know the details for the other applications. Maybe someone from
InkScape can tell us.


>
> >
> >
> > No seriously, most people I spoke with thought that masking would
> operate on the alpha channel initially. It just seems to be more intuitive.
> However, in SVG we will actually support both!
> >
> > Did you talk to graphic designers, or people that design web pages or
> browsers?
> > My issue is not with having both; it's with having them being
> inconsistent + having a default that is rarely used for vector data
> I am talking to people on IRC that blame the implementation to be wrong. I
> replied on bug reports that were created because of the same
> misunderstanding. I assume that they are content creators, otherwise they
> wouldn't try to create content :P


OK, so they misunderstand.
If they were to create slightly more complex mask than simple shapes, they
would find out that luminosity is much easier to work with.


> >
> >
> >
> > > My number does not include Flash since it doesn't have luminosity
> masks (only alpha) so people didn't have choice but I've seen workaround
> using pixel bender.
> > Sounds like authors are already more familiar with alpha masks.
> >
> > No, some advanced flash designers are familiar with working around alpha
> mask's limitations because they want luminosity.
> That might be. On SVG a lot people tried to do the opposite and can't
> understand why luminance is used. It is of course hard to say if one or the
> other side is the majority. My experience is that most people try to use
> alpha masking first and are frustrated that their content doesn't work.
>
> As consensus I would suggest adding an issue in the spec to ask for author
> feedback for a while. If we receive negative feedback, we can change it to
> luminance. A blog post might help to reach designers and ask them for
> responses. I expect to get more feedback why we don't change the default
> for masking to alpha in general :).
>

Designers don't know what the underlying technology does. They see options
in dialogs for fancy dropshadows and glows and have no idea how many
masking/blending/compositing operations those result in.

The option in Illustrator is called "create opacity mask" which sounds like
"alpha mask", but it's really a "luminosity mask"


> >
> >
> >
> > >
> > > For some operations that look like they could use alpha masks (like
> gradient shadows), our products still use luminosity. I can't remember the
> details but I can ask.
> > >
> > > Rik
> > >
> > > On Mon, Jul 30, 2012 at 5:16 PM, Dirk Schulze <dschulze@adobe.com>
> wrote:
> > >
> > > On Jul 30, 2012, at 4:57 PM, "Rik Cabanier" <cabanier@adobe.com>
> wrote:
> > >
> > > > Looking at current vector artwork, 99.99% is using luminosity.
> > > That is an interesting number, where did you get this number and which
> vector artwork are you referring?
> > >
> > > Dirk
> > >
> > > > It's much easier to manipulate for a designer than alpha (since it's
> easier to visualize and since overlapping elements with alpha interact with
> each other)
> > > >
> > > > Rik
> > > >
> > > >> -----Original Message-----
> > > >> From: Tab Atkins Jr. [mailto:jackalmage@gmail.com]
> > > >> Sent: Monday, July 30, 2012 4:48 PM
> > > >> To: Rik Cabanier
> > > >> Cc: www-svg@w3.org
> > > >> Subject: Re: mask: luminance or alpha
> > > >>
> > > >> On Mon, Jul 30, 2012 at 4:13 PM, Rik Cabanier <cabanier@adobe.com>
> > > >> wrote:
> > > >>> Last week, there was a decision to have the id-less mask have
> ‘alpha’
> > > >>> as the default instead of ‘luminance’
> > > >>>
> > > >>> Can someone explain the rational for doing this again?
> > > >>>
> > > >>> It changes existing default behavior, is not what people want or
> what
> > > >>> products like Illustrator and InkScape currently support.
> > > >>
> > > >> The idea is that this *is* what people want.  We just can't change
> <mask>'s
> > > >> default behavior due to legacy compat.
> > > >>
> > > >> ~TJ
> > >
> >
> >
>
>
Received on Tuesday, 31 July 2012 04:07:25 GMT

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