Method A:
Starting from Corona 12 Update 1, a new set of Auto Adjustment features has been introduced. These options allow users to quickly fix the exposure and white balance of a render inside the VFB.
To start using the Auto Adjustment features, follow these steps:
- Enable the "Auto Adjustment" option in the Post tab of the Corona VFB.
- Make sure White Balance is enabled.
- Use the Strength parameter to control how strong the auto white balance effect is.
- Click the "Bake" button to move the current white balance value from the "Auto Adjustment" section to the Tone mapping operators section.
- For animations, you can enable "Update during animation" to automatically adjust the white balance in each frame.
Method B:
Note: Starting from Corona 12 Update 1, the White Balance operator has been deprecated and is now called "Legacy White Balance." The new White Balance operator uses Bradford's chromatic adaptation formula, which makes it more accurate and in-line with industry standard.
In Corona, it is possible to use the Corona Color Picker to set an automatic white balance for your image directly in the VFB:
1. Add the Tint to the Tone Mapping settings (+ -> Basic (Tint) )
2. Click on the "Color tint" swatch in the VFB - the Corona Color Picker should pop up
3. Click on the "Pick inverse" button (icon on the bottom of the color selector window, next to the regular "Pick color" button)
4. Left-click on any pixel in the rendered image - it will be considered neutral gray
5. The color tint will be adjusted automatically and applied to your image
Note: it is also possible to set the white balance based on more pixels than just a single one. To do it, select the desired option from the "Point Sample" dropdown list next to the color picker buttons.