Re: mask: luminance or alpha

On Mon, Jul 30, 2012 at 9:12 PM, Tab Atkins Jr. <jackalmage@gmail.com>wrote:

> On Mon, Jul 30, 2012 at 9:06 PM, Rik Cabanier <cabanier@gmail.com> wrote:
> > 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"
>
> I definitely know that in my first experience with <mask>, I tried to
> use a gradient from black to transparent, and was very confused.  It
> seemed intuitively obvious that the mask would "transfer" its own
> alpha to the content.


Yeah. I remember being surprised too that lllustrator doesn't mask with
alpha values.
After I saw how artists were using luminosity masks, it started to make
more sense (ie a flower petal that uses itself as a mask. Where the leave
is lighter, it lets more 'light' through)

Rik