Don't affect colors (adaptation only) question

[jujubee]

I've seen a couple people tell others when working in Linear Workflow (LWF) to check 'Don't affect colors.'

I believe this is incorrect information but could be wrong.

This is from the help files:

Don't affect colors (adaptation only) - when this parameter is on, the color mapping will not be applied to the final image, however V-Ray will proceed with all its calculations as though color mapping is applied (e.g. the noise levels will be corrected accordingly). This can be useful, for example, if you know that you will apply some color correction to the image later on, but wish to keep the rendering itself in linear space for compositing purposes.

[DaForce]

Well it depends how you work with LWF.

If you bake everything in and render straight out as a JPG with no real post work or something then the option is of no good to you

If you prefer to do all your gamma and color mapping in post then this option is good, as it enables the advantages of color mapping such as better sampling in the dark areas without baking in anything and messing up the linear output.

atleast ... AFAIK.

[cpnichols]

Don't affect colors will only do something if you have some value set in the color mapping. Best use is to set the gamma to 2.2 but don't affect colors. That way, you reduce the noise in your shadows/darks, but your data is still linear.

I have a Gnomonology Tutorial where I show this.

[sv]

yes, for a linear workflow it is an extremely good feature.

[jujubee]

Thanks guys for your replies. Well, I bake in my LWF:

Max Preferences
Max Gamma: 2.2
Affect Material Editor: Checked
Input Gamma: 2.2

Color Mapping
Linear Multiply
Dark Multiplier: 1.0
Bright Multiplier: 1.0
Gamma: 2.2

I always render to VrayFrameBuffer.

If I render with 'Don't affect colors' checked, the VrayFrameBuffer is VERY dark. If I hit the 'sRGB' button at the bottom of the VrayFrameBuffer, then the image looks like a regular render with 'Don't affect colors' unchecked.

I guess I'm kind of wondering what the difference is (or if I've been doing anything wrong...)

[instinct]

Well...dont affect colors does what it says : it doesnt affect colors. Only the adaption (simply speaking, the DMC sampler). That is only meant to be used if you DONT want to bake your LWF. That means you have to work in linear space in post and you can use the sRGB button to preview the actual result. the sRGB button is ONLY for preview it doesnt change the saved image. We use linear from 3d to 2d with nuke. Working in linear is a hassle if possible at all in all apps i worked with besides nuke.

Regards,
Thorsten

[ene.xis]

it affects the way vray will sample ur render

if the darker areas are per se harder to sample, and u are outputing images with gamma 1 (lwf), these will be darker then if u with the bake gamma curve baked into it. Being darker it will tend to be more noisier due to the "darkness".
The don t affect collors tells vray to sample the image as it would if u were baking the gamma curve, wich u don t wan t in order to keep the process linear.

It s in fact basicly an srgb button to dmc itself!
(or please do correct if im wrong!)

[instinct]

It s in fact basicly an srgb button to dmc itself!
(or please do correct if im wrong!)

nope you arent and i need to write a memo to myself with that explanation...hits the nail on the head

Regards,
Thorsten

[jujubee]

So basically I should use this and use the sRGB button to preview it accurately. It is mostly a post processing workflow.

[DaForce]

Basically if you bake not much point using it as you get teh final result you want anyway.
If you do post work for your color changes then its worthwhile as the colormapping sampling reduces noise in darker areas withouth messing up your linear image.