[Bf-committers] Color pipeline todo: alpha

[Ton Roosendaal]

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
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