obs-filters: Add white balance to color filter

[mar10iana]

Description

We added three white balance sliders to the color correction filter, as shown on the screenshots below:

The following changes have been made to the code:

• Added new settings for red, green, and blue white balance adjustments.
• Updated the color_correction_filter_data structure to include white balance variables.
• Modified the create functions to initialize the white balance values.
• Implemented white balance matrix computation in the update functions.
• Integrated the white balance matrix into the final matrix used for color correction.
• Updated the properties functions to add sliders for white balance adjustments.
• Set default values for the new white balance settings.

Motivation and Context

Currently, OBS offers a variety of color correction filters, but lacks a dedicated white balance feature, which is essential for many users. This feature aims to address this problem by introducing three white balance sliders (red, green and blue) that adjust the color temperature.

Ideas website link: https://ideas.obsproject.com/posts/2582/white-balance

How Has This Been Tested?

We tested our feature in a macOS environment.
To test this feature you should go to the color correction filter and check the newly added sliders. If you change the value of the slider, the colours of your source will be updated.

Types of changes

• New feature (non-breaking change which adds functionality)

Checklist:

• My code has been run through clang-format.
• I have read the contributing document.
• My code is not on the master branch.
• The code has been tested.
• All commit messages are properly formatted and commits squashed where appropriate.
• I have included updates to all appropriate documentation.

[WizardCM]

Is it common for white balance to be split into three separate sliders? Keeping in mind OBS is used by a variety of users, some with very intricate knowledge of video/colour and others who just want to make it look good with as little configuration as possible.

[RytoEX]

Do not use merge commits to catch up on branch/repo history. Use git rebase.

[mar10iana]

Is it common for white balance to be split into three separate sliders? Keeping in mind OBS is used by a variety of users, some with very intricate knowledge of video/colour and others who just want to make it look good with as little configuration as possible.

This method offers the highest level of control, allowing precise fine-tuning of color balance across the spectrum. It's ideal for professional users who need to correct complex color casts or achieve specific color grading effects.
For regular users, like myself, despite not being the simplest option, I still find this method pretty straightforward to use.
But ultimately it is up to you guys! We can change it if needed :)