Color clampin

[DKVISION]

Hallo

Perhaps, it's annoying. But I have a problem with the missing colour clamp option in CPU render.
I have a render I had some problems in post processing (Fusion).. I render in half float (linear) and the image "has a hole".
When I had this before I just could clamp the colour values and everything was fine but now...
I tried the script, but it sems not to work with Vray 6. In the Image are pixel with a value RGB value of 64,000 64,000 64,000 and more, it's the vray sun!

It seems that Fusion can't work with such high values, and some tools in Fusion too.

In some cases I also got a lot faster render on certain scenes when turning on clamp colours!

Please bring it back!

[hermit.crab]

Are you referring to the Color mapping option? If you want a clamped image maybe the "Exponential" type should be of use.

[DKVISION]

Yes, I mean the Clamp for Color mapping. I need linear renderings for the postproduction.
I jsut strted to use Vray 6 for a few weeks, so I never ran in this problem with vray next, colour clamp was an easy fix.
The problem occured also several times with highlights on reflective surfaces, colour clamp saved "my life" quite often.

[^Lele^]

You should simply need to save the image as 32bpc float, for the range issues.
We'll look into what can be done for Clamping, it didn't play well as it used to be with a host of other tech brought forward in v5 and v6.
Maybe we can find a better way around long renders of highlights.

[Joelaff]

Fusion should be able to handle values that high. What are your alpha values? You do need to make sure those are between 0 and 1.0. You can clamp those in Fusion with a BC set to affect alpha only, and set to clamp. When you see weird colors like that in Fusion most of the time it is related to bad alpha values (even negative), which some tools can cause due to filter ringing. ( https://en.wikipedia.org/wiki/Ringing_artifacts ). So try the BC clamping after any filters (esp blurs/sharpens).

I am working with an EXR render that has much higher values than that right now for the VRaySun:

It works fine in Fusion.

VRay definitely has issues with bright highlights (small speculars). This is especially true when using VRaySun. One way to improve this is to use a separate disc VRayLight for specular/reflection, and make that light slightly larger, also don't set its Directional parameter too high (even though the sun is 100% directional/parallel-- try something like 0.3-0.8 tops).

Clamp was a great feature, and I don't understand ever removing features. (This is a repeating theme for me.)

I would say this issue with speculars is probably the number one issue with VRay right now in terms of killing productivity. It makes render times go through the roof for shots with depth of field ON where the out of focus areas have such highlights. This requires countless tests, and workarounds to get things clean on time.