Render is not applying composited FX properly

Support Lighting and Rendering
1

It is my first time compositing a render in blender and I’ve run into this issue that has got me stumped. For some reason, my renders are not coming out in the way that they appear with the view node in the compositor. The image is still being rendered with some of the composited FX, but it does not look the same.

Additionally, it seems that composited FX aren’t appearing in the render unless they are within the scene geometry. In this case it is the glare on the text, for some reason this does not want to render above the transparent background.

This is the image before compositing:

image
image967×364 72.2 KB

The site doesn’t let me embed more than one image per post since I am a ‘new user’ so I will provide the rest in the replies.

Any help is appreciated :slight_smile:

2

This is the image via the viewer node in the compositor (how it should look):

image
image940×361 76.9 KB

3

This is the image when I render it out (how it shouldnt look):

image
image1777×727 156 KB

(dont mind the opaque background, this is from me screengrabbing windows Photos)

4

And this is the node setup:

image
image1310×744 163 KB

5

I’ve noticed if I save the image with “Use Alpha” disabled it fixes all the issues, but I need a transparent background for this image, any ideas?

6

After a bit of research, it seems this has to do with the way the mix node handles alpha: it uses only the alpha of the first image.

The way I found to fix it is to manually add the glare’s result to the render’s alpha and then plug that in the alpha output.

comp
comp962×865 55.3 KB

However, once you have saved the image, the alpha layer will cause the glare to get mixed with the background color behind your letters, the color you would see if the image didn’t have transparency. So you will need to have the image’s background be the color you want your glare to have in the final result. That way, you can get close to what you want, but it will always look slightly different from the compositor.

Are the letters slightly transparent? If yes, that could explain their different look. They get blended with the background color differently depending on how the alpha is applied/calculated.