Chaos Corona Forum

Chaos Corona for 3ds Max => [Max] Bug Reporting => [Max] Resolved Bugs => Topic started by: aaouviz on 2019-10-17, 11:57:05

Title: Wrong color correct temp
Post by: aaouviz on 2019-10-17, 11:57:05

Hi, sorry if this has been fixed (Im still on Version 4).

It seems to be the colour correct temperature is backwards? Please see attached, should be pretty self-explanatory...

A lower value (more blue) should make the image cooler (more blue), correct? And vie-versa, a warmer (more red) should be warmer?

Title: Re: Wrong color correct temp
Post by: Juraj on 2019-10-17, 12:27:33

I don't see any mistake:

Your first image has Color Balance 4500K. 4500K is warm color that is substracted from image so it will be (6500K -4500K=2000K) cooler.
Your second images has Color Balance of 8000K. 8000K is light blueish color that is substracted, it will be 2000K warmer.

It works identically to how it is in physical camera (and real-world camera and photo RAW editors).

Title: Re: Wrong color correct temp
Post by: aaouviz on 2019-10-17, 13:09:14

Hi Juraj,

Thanks for the clarification.

I was not aware that the colour balance is subtracted.

Slightly counter-intuitive but I guess this makes sense then. Thanks again,

Title: Re: Wrong color correct temp
Post by: Juraj on 2019-10-17, 13:36:35

At first sight I agree, it might seem counterintuitive. But you have to consider the logic where it came from in photography.

It helps you easily balance against known black-body temperatures, so if light-bulb lit set of 2800K, you want to achieve correct white, you set the white 'balance' to 2800K.
If common daylight temperature is 5000-5500K +/- in Central Europe midday, you will set your white-balance to roughly this, and you don't even have to search for any white object in your scene, or bring grey-card along. You don't need to do any math.

It is intuitive for the given purpose :- ).