On Tue, Mar 11, 2003 at 07:15:16PM +0100, Raphaël Quinet wrote:
> On Tue, 11 Mar 2003 18:55:33 +0100, "David Necas (Yeti)" <[EMAIL PROTECTED]> wrote:
> 
> Your example is fine, except for the last step using Noisify on the
> alpha channel.  As Adam pointed out in his previous messages, the
> correct way to acheive the same effect would be to use Noisify on a
> layer mask, not on the alpha channel.
> 
> Noisify and other plug-ins such as Hurl/Pick/Slur should never make a
> transparent pixel non-transparent (except maybe by working with
> pre-multiplied alpha, as I suggested in the bug report).  So either we
> completely disable the option to work on the alpha channel, or we
> change the code in such a way that the noise can only increase the
> transparency, but not decrease it (i.e., "creating" color in a
> transparent area).

I'm for disabling operation on alpha completely (I'll fix it
this way when I find some time).  IIRC this means removing
the Alpha slider (and corresponding functionality) from
Noisify and changing Hurl/Pick/Slur to work only on color
channels. I can't imagine how it could do anything both
useful and politically correct with alpha.  (Feel free to
suggest something, but working on premultiplied alpha
satisfies only the second condition, because no one wants to
average pixels with invisible black).

Everyone will have to learn how to use Layer Masks then --
but, well, that's not my problem -- if usability people
think this is the right approach, who I am to oppose ;-)

Yeti

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