As a Roblox developer, it’s impossible to adjust colour temperature of scenes, which makes it difficult to work with realistic lighting.
It’s common for light fixtures to use CCT (correlated colour temperature) to communicate the colour of the light they emit, using a Kelvin temperature.
So, suppose that I would like to use lights in my Roblox build that correspond to these real-world colours.
This is possible to do; there exist algorithms that take these ‘colour temperatures’ and turn them into RGB.
Let’s start with 6500K lights; these are meant to be equivalent to the colour of daylight. This looks fine so far - daylight appears white.
Now, let’s switch out those lights for 3000K lights (commonly called “warm white” or “soft white”).
The scene colour is incredibly off-balance. That’s because the algorithm used for obtaining the RGB colours assumes that daylight should appear white. By comparison, the kinds of lights we use indoors are much more orange in colour, and that’s what we see here plainly.
Tom Scott demonstrates the effect in a real camera:
The way you solve this, as Tom alludes to, is to configure what the camera sees as ‘white’. This is known as ‘white balance’ or ‘colour balance’.
The following pictures from Wikipedia illustrate the effect. Here is the base image:
By changing the white balance, the apparent colour temperature of the image shifts. We can the lighting look warmer (lower Kelvin):
Or colder (higher Kelvin):
This can be used to correct for ‘too-orange’ or ‘too-blue’ images due to the use of light sources other than daylight.
White balance tools are a standard part of almost all photo editing tools. Here, I can attempt to crudely approximate how white balancing works on the Roblox scene above, using one such tool.
This doesn’t quite work because it’s not properly part of the rendering pipeline, but you should see the image becomes more white-ish.
If Roblox were to implement this, it would enable artists to work with more realistic lighting colours, enabling the mixing of different coloured lights in a realistic way.
In particular, it would allow for artists to mix warm indoor lighting with cool outdoor lighting in difficult scenes, and adjust whether the camera is adjusted for indoor or outdoor lighting based on whether they’re inside or outside.
