[Bf-committers] Cycles: Image Texture Node, color output still gets alpha channel mixed

Alberto Torres kungfoobar at gmail.com
Thu Nov 9 00:37:40 CET 2017

Testing with 2.79:

- Changing the alpha setting (straight/premultipied) doesn't have an effect.
- Worse of all, setting the texture to "non color data" it's still
multiplying the "color" channels.

So there's no workaround other than duplicating the image which defeats the
I've tried this workaround <https://i.imgur.com/lHJ8R1t.png> which kinda
works if the alpha channel doesn't have too low values.

I think you should file a bug report.


On Wed, Nov 8, 2017 at 1:02 PM, Porces <porces at gmail.com> wrote:

> Hi all,
> I've noticed in the Image Texture node, that when we have the 'use_alpha'
> option turned on on the image datablock, the color output get's multiplied
> by the alpha channel.
> On the other hand, if the 'use_alpha' is off, then the alpha output returns
> 0.
> This is somewhat a strange behaviour for the Image Texture node in Cycles,
> and in my opinion we should only output the color channels through the
> color output, and the alpha through the alpha output (no matter if
> 'use_alpha' is on or off, since we already separate the channels in the
> node).
> For example, if the alpha channel is used for storing any other
> information, like roughness or AO, this messes up with the color output,
> and we need to have two different datablocks with different settings for
> dealing with the same texture
> I wonder if there's some reason for this to work like this, or if we could
> change it.
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