Cycles & nodes: Can blacks be made transparent?

On a ‘billboard’ plane, I would like to use an image texture of a flame on a black background, but somehow have the black be transparent so that only the flame appears. So far, I have not found a node arrangement that will do it. I can’t get Cycles to treat the black as an alpha channel.

Thanks for any clues.

Well, I’ve just tried it in the compositor with an image with a lot of black and filtered the black with Converter > Math > Greater Than - the first one is the image, and the second is a value of 0.0, and if you want you can increase a little bit to remove other parts that are still dark. Finally you put the output into the alpha.
If you want to do it for a material should be the same case, but instead, you put a mix node and put as factor the output of the Greater Than node for the transparency. :RocknRoll:

[ATTACH=CONFIG]271050[/ATTACH]
This image is in the case you’re using the compositor

[ATTACH=CONFIG]271055[/ATTACH]
And this other one is in the case you are making a material…

I hope that this is what you need :eyebrowlift2:

Well, I’ve just tried it in the compositor with an image with a lot of black and filtered the black with Converter > Math > Greater Than - the first one is the image, and the second is a value of 0.0, and if you want you can increase a little bit to remove other parts that are still dark. Finally you put the output into the alpha.
If you want to do it for a material should be the same case, but instead, you put a mix node and put as factor the output of the Greater Than node for the transparency. :RocknRoll:

[ATTACH=CONFIG]271050[/ATTACH]
This image is in the case you’re using the compositor

[ATTACH=CONFIG]271055[/ATTACH]
And this other one is in the case you are making a material…

I hope that this is what you need :eyebrowlift2:

Try this


Rich33584,

That worked perfectly - and the brightness is adjustable using the emission slider. Thank you VERY much. I would never have found that on my own. It will go into my collection. Thanks again.

If you just add the Emission and the Transparent shaders together, you’ll do away with the dark outline around the flame

can you explain how the fire and smoke was done
and wath the iamge is in you other thread

looks interesting but not certain if realist may be
dd you try to do fire with mesh and proc texture ?

happy bl