Help with colour mapping...?

[Coolhand78]

Hi guys,

 

I need some help understanding the color mapping rollout in vray...

I'm using lwf and am unsure about the 'don't affect colors (adaption only)'

Particularly in combination with sRGB button on the VFB...

 

What is the correct usage of these two options when using linear multiply and/or Reinhard colour mapping?

 

Thanks

[RyderSK]

It let's you keep linear output but will manage the internal computation in predefined gamma space ( by default 2.2. instead of linear 1.0 ).

The original idea was to get the best of both worlds, i.e, linear output for full compositing (thus requiring sRGB button for correct preview in framebuffer), and noise levels which are better sorted at gamma 2.2 (or, occasionaly, slightly higher even, as it's ony for internal computations).

 

The name is odd, and it got renamed since. Have you updated to 2.4.04 ?

 

Nonetheless, through constant adjustments done by Chaos, it currently shouldn't even matter if that was used or not. It would provide better sampling, but slightly higher render time, while "original" linear (ie. 1.0/1.0 ) would provide more noise but slightly faster so in the end, it would be the same. Just like everything in Vray.

[Coolhand78]

It let's you keep linear output but will manage the internal computation in predefined gamma space ( by default 2.2. instead of linear 1.0 ).

The original idea was to get the best of both worlds, i.e, linear output for full compositing (thus requiring sRGB button for correct preview in framebuffer), and noise levels which are better sorted at gamma 2.2 (or, occasionaly, slightly higher even, as it's ony for internal computations).

 

The name is odd, and it got renamed since. Have you updated to 2.4.04 ?

 

Nonetheless, through constant adjustments done by Chaos, it currently shouldn't even matter if that was used or not. It would provide better sampling, but slightly higher render time, while "original" linear (ie. 1.0/1.0 ) would provide more noise but slightly faster so in the end, it would be the same. Just like everything in Vray.

 

Hey Juraj,

 

thanks for the reply. So I should be using it (don't affect colours) and the sRGB button in combination with each other? I save my rendered images out as .exr, what bearing will it have on this?

 

I also set my Gamma/LUT input and output to 2.2 and 1.0 respectively, will that have any bearing on the use of the don't affect colours or the sRGB button (well not in the case of input)

 

sorry for the questions but I'm really trying to understand how the whole lwf thing works, i've read all the theory numerous times, but with out actual examples its just not gelling for me...

 

we have not yet upgraded, i've been lampooning for a long time but am not getting anywhere, we're still using max 2011 as well...

 

are you using corona exclusively now? or do you still work with Vray?

[RyderSK]

I am using both Vray and Corona. It won't change in nearest future.

 

sRGB is just preview button, it doesn't affect anything, it's there to help you view your "linear image (gamma 1.0)" as regular sRGB fashion (gamma 2.2).

 

All the calculations are linear anyway, there is no other way, there is only linear way and wrong way. End of it.

 

Depending on your post-production, linear here means saving in linear output (gamma 1.0), Gamma/LUT presets can be override, they just set defaults, so if you have output on 1.0, you can save safely directly into .openexr knowing it will save correctly in linear output.

 

Yes, you can just keep Don't affect colours by default on, it's mostly preferable way, then you Gamma in Vray rollout should be set at 2.2. (internally it would still be 1.0 to gauge sampling, but really, it's linear in every possible way always, no matter what you set.).

 

There's almost no way to make anything incorrect. Any combinations of buttons (except for "linear workflow" which is outdated fast way to convert old scenes, shouldn't be touched), you push, you will still achieve correct result.

 

If you decide to go baked-in gamma workflow and don't require linear compositing (and associated benefits, such as exposure adjustment if you used un-clumped rendering), you can set your colour mapping to Rheinhard or exponential, and you no longer need sRGB button ticked on because your framebuffer (and hence also output) will be in sRGB/2.2 already.

 

I guess it sounds confusing at first...but it's not, it's actually very very simple, people just look too much into it.

[Coolhand78]

thanks again mate,

I use photoshop and lightroom for post work as I rarely ever create animations and i'm not very familiar with after effects, though i would like

to get into it a bit more for its 32 Bit capabilities.

 

thanks for your advice Juraj, i genuinely appreciate your input, i think i'm getting it

 

Off topic a bit, but how do you decide when to use corona or vray?