[Bf-committers] Color pipeline todo: alpha

[François T.]

IMO, the term associated/unassociated is very technical. As Bretch mention,
he likes it because its how data are stores. But while it probably speaks
to him, honestly, before reading in depth about mechanics and formulas and
algorithm, as an artist I never saw it in softwares (or never thought it
was related to that topic) before. While I always heard about premult
(cross softwares, cross industries, cross department)
Yes it is speculation, but this is a developer mailing list, don't assume
the artist which are in the front end, knows or are use to your "correct"
naming convention.


2012/12/21 Ton Roosendaal <ton at blender.org>

> Hi,
>
> I honestly can't guess which of the associations would be which alpha or
> color.
> This will lead to a lot of confused people.
>
> -Ton-
>
> ------------------------------------------------------------------------
> Ton Roosendaal  Blender Foundation   ton at blender.org    www.blender.org
> Blender Institute   Entrepotdok 57A  1018AD Amsterdam   The Netherlands
>
> On 20 Dec, 2012, at 20:52, Brecht Van Lommel wrote:
>
> > I like the names associated and unassociated because they don't
> > describe how you arrived at the color, just the way it is stored. For
> > rendering you don't premultiply things, it just comes out that way
> > naturally. Though perhaps the terms premultiplied/unpremultiplied are
> > more familiar to users.
> >
> > Brecht.
> >
> > On Thu, Dec 20, 2012 at 8:33 PM, Ton Roosendaal <ton at blender.org> wrote:
> >> Hi,
> >>
> >> The convention is probably based on where the graphics comes from.
> >>
> >> - Straight alpha:
> >> Painted graphics and exporting it with an alpha mask. Colors remain
> unchanged.
> >>
> >> - Unpremultiplied color:
> >> Images from render and composite, converted to display color.
> >>
> >> - Premultiplied color:
> >> A straight alpha image, converted to to premultiplied colors.
> >>
> >> Each is actually different :)
> >>
> >> -Ton-
> >>
> >> ------------------------------------------------------------------------
> >> Ton Roosendaal  Blender Foundation   ton at blender.org    www.blender.org
> >> Blender Institute   Entrepotdok 57A  1018AD Amsterdam   The Netherlands
> >>
> >> On 20 Dec, 2012, at 20:20, Troy Sobotka wrote:
> >>
> >>> On Thu, Dec 20, 2012 at 10:36 AM, Brecht Van Lommel
> >>> <brechtvanlommel at pandora.be> wrote:
> >>>> Premul for float and key for byte images could work.
> >>>
> >>> Just in the interest of consistency, if we are going with
> >>> "Premultiplied" naming convention, can we roll with the inverse of
> >>> "Unpremultiplied" and apply it consistently?
> >>>
> >>> I checked in with Mr. Selan and he suggested that "Unpremultiplied" as
> >>> consistent. Mr. Gritz uses[1] the TIFF convention of "Associated" and
> >>> "Unassociated" convention.
> >>>
> >>> I'm open to whatever naming convention we rest on, and only hope we
> >>> can apply it consistently throughout the interface. In particular, the
> >>> sidebar panels should likely list "Premultiplied" and the node
> >>> conversion should reference "Premultiplied" and "Unpremultiplied."[2]
> >>>
> >>> The "Color Unpremultiply" term should probably be re-evaluated to
> >>> avoid confusion, as it is an order of operations event, and the
> >>> current label is far to close to the other terms which can only amount
> >>> to greater confusion.
> >>>
> >>> Blender needs to take whatever path is most healthy for it, but we can
> >>> at least aim to apply the terminology consistently.
> >>>
> >>> With respect,
> >>> TJS
> >>>
> >>> [1]
> http://lists.openimageio.org/pipermail/oiio-dev-openimageio.org/2011-April/004193.html
> >>> [2] http://comments.gmane.org/gmane.comp.lib.openimageio.devel/1406
> >>> _______________________________________________
> >>> Bf-committers mailing list
> >>> Bf-committers at blender.org
> >>> http://lists.blender.org/mailman/listinfo/bf-committers
> >>
> >> _______________________________________________
> >> Bf-committers mailing list
> >> Bf-committers at blender.org
> >> http://lists.blender.org/mailman/listinfo/bf-committers
> > _______________________________________________
> > Bf-committers mailing list
> > Bf-committers at blender.org
> > http://lists.blender.org/mailman/listinfo/bf-committers
>
> _______________________________________________
> Bf-committers mailing list
> Bf-committers at blender.org
> http://lists.blender.org/mailman/listinfo/bf-committers
>



-- 
____________________
François Tarlier
www.francois-tarlier.com
www.linkedin.com/in/francoistarlier