Adding a lightmix to a composite causes the image to be overexposed

[roysgi]

Hi.
See attached. I did not change anything in the lighting values (all 1) in the lightmix layer
And still gets overexposure. What is the correct way to add the lightmix to the composite without getting the overexposure?
Thanks

[piotrus3333]

lightmix equals beauty hence double exposure.

[hermit.crab]

Yes, there's a doubling of the lights' effect. You may use the "To scene" option (after manipulating the lights), render again, and afterward work only with the Back to Beauty elements.

[roysgi]

Thanks.

If I understood correctly then what you are actually saying is that I will never be able to work with lightmix and renderelement and see their effect simultaneously in VFB.
Would be very helpful if there was this option without the need for "to scene"
And render twice

[yavor.rubenov]

If I understood correctly then what you are actually saying is that I will never be able to work with lightmix and renderelement and see their effect simultaneously in VFB.

Not sure what you mean to work with them simultaneously - they represent the same thing (Beauty) but split in different ways. How can you work with them simultaneously and not have twice the final result ?

[roysgi]

Thanks Yavor
My goal is to better understand how to compose in VFB using renderelement without the need for external editing software.
First I change some things in the renderelement layers.
For example: Increases the multiplier of reflection and globalillumination. After I get the desired result I want to make some adjustments to the lighting - for example to give a different color to a certain light, decrease the intensity of another light etc. But when I go to lightmix and want to change, I see the original rgb image as if I did not make any change to reflection And the globalilumination I did earlier.
Something in my understanding about the whole process is lacking. I would love an explanation of how to properly perform the process.
Thanks again

[piotrus3333]

you need „back to beauty” for every light you need to adjust. default lightmix gives you LightSelects with everything in one element.

[piotrus3333]

see LightSelect options: you can get separately: direct, gi and spec.

[matanov]

Like Yavor said, it's the same image but split in 2 different ways:

1. LightMix - the final image is composed on a light contribution base, meaning that each LM entry (full VRayLightSelect underneath) compounds the entire contribution for that particular light(s) in the scene.
2. BackToBeauty - the final image is composed on a element (Reflection/Refraction/GI... etc)contribution base. Each element has the respective contribution part of all lights in the scene - f.e. the GI of all lights is in the GI element.

In your case you can make a hybrid (not a recommended workflow but the VFB is agile enough to do it) - base your Composite layer tree on a LightMix and then on top of the LM folder first subtract the element you want to adjust and then add it back with the corrections you want.

[^Lele^]

Or, you know, split components per light with LPEs.
Good luck with the number of REs to fiddle with, if the lights are numerous.

[roysgi]

Thanks to all the respondents.
So if I understood correctly Peter, use either lightmix or backtobeauty but not both. Suppose I just want to increase the reflection and change the lighting (color, intensity, etc.). Is the correct way to do this as in the attachment? - that is, move the lightmix to composite and add only reflection RE above and not use backtobeauty RE at all?
Thank you for your patience

[matanov]

You have to first subtract (with mult=1) whatever you want to add corrected because you already have all beauty elements integrated in the LightMix -

[roysgi]

Thanks Peter at the end I will understand
So why did you actually add the reflection layer in subtract blending?
After all, I can only add one layer of reflection in add blending
And get the same result (just adjust the multiplier with lower values)

[matanov]

If you do not subtract it before adding the adjusted one, the comp will be wrong. But after all as long as you like the end result - it's up to you what you'll add

[roysgi]

Great thanks