How to save effects alpha

Hi everybody!
How can I save the alpha for, lets say a glare effect? I see in the output node that the alpha is rendered correctly, I mean the transparency of the glare effect, but when I save it to PNG or TIFF it only saves the original alpha of the image (before the glare node).
Is it a bug?

Huh, it looks like the fileoutput node does not support alpha, only Z.

So yes, it is a bug, or more accurately a feature not yet implemented.

I see, I was hoping that wouldn’t be the case. It’s a shame because I can see the glare’s alpha perfectly rendered in the node viewer but have no way to save it. I guess I’ll have to suggest it as a feature.

File output supports alpha, it just uses the alpha that’s included in the color line rather than have a separate line for alpha. I’ve used it many times before. Be sure you have the output in the main render settings set to RGBA not RGB, or else it won’t work.

Hi, LazyCoder (I’m a Lazy Designer)
Yes, I know how to save images with an Alpha channel, the problem is that anything you can composite wich affects alpha and even alpha afected transparency, doesn’t get saved.
I have a software package standing on a reflective floor and with a nice glare, and I want to export it to photoshop for a web desing. I want to use the apha of my reflection and glare to put the image over a background, and choose any color I want for the background but…It’s impossible (well maybe almost impossible since maybe someone comes up with a solution).
Not the transparency alpha, nor the transparency of the glare get saved in any alpha supporting format in Blender.
You can do this easily in 3dsMax, but I love Blender soooo much:yes:…

Yeh, I noticed that too. I got around this by using a seperate render layer, converting the color to black and white adjusting the curves and using that output as the alpha layer in the combiner node.

click RGBA button to save alpha channel.

Sure this has been brought up before by Lancer and he found a work around. Try PMing him or searching his posts maybe.

Thanks Yellow, I’ll try that.
That’s not the problem, the problem is Blender can’t save alpha reflections or effects alpha, which is a headache if you are going to composite outside Blender.

Blender does save transparency in images, at least what I call alpha, and I use them all the time to composite outside Blender. I am doing that today, as a matter of fact. Change the reflecting plane alpha to <1, and you will be able to composite your package’s reflection over any color/image. Use ZTransparency and no world so that your reflections wont be artificially colored.


effects-transparency.blend (330 KB)

@PapaSmurf, Yeah but your scene does not have any node effects in it. Try adding a glare and getting the actual alpha of the glare. Maybe I am wrong, but I think that is what the poster is trying to achieve.

Here is an example file, how do I get the alpha of the blur?


animated_blur_node.blend (106 KB)

Atom, that’s exactly what I was reffering to. I use Glare a lot (not only for glare effects, by the way) And I have no way of saving it to an alpha supporting format, yet I can see the alpha in the final viewer node,…weird.
Maybe somebody knows a workaround for this.
Sorry, I should have mentioned I was refering to ray-traced transparency, not ZTrans.

Ah, in compositing nodes, sorry, missed that part. Depending on the node, you are either adding color and/or alpha. If a node, like Glare, does not mess with the alpha channel, or messes with it in ways you do not like, then use a gray-scale mask and the setAlpha node as shown in the pic to set the alpha channel. Here I converted the glow to a mask using the colorramp, and added that to the original image’s alpha channel, and used the result as the alpha channel in the output.

Or just do all your compositing in Blender, and bring in your background image via image input and alphaover your box on top of the image. Since you are mixing colors at that point, it will look fine.