In this post I am going to share a quick tip on how to white balance your images inside nuke without “burning” your image with the withepoint default control. The basic idea is to average out the values from the whitepoint.
I am using the image above for our example. It’s an HDR image with values higher than 1.
Start by creating a grade node and pick a reference point for the whitepoint. As you see this will wildly change your image luminance. So we need to find a way to keep the values under control.
Create whitebalance control
Right click in your node proprieties bin and select manage user knobs… in the Add dropdown select RGB Color Knob, name it “whiteBalance”, click ok and then done to close the creation window.
In your node “user” tab you should have a color picker, use it to pick a color area of your image where you think it should be white. Your viewer should be connected to the original image so you dont pick the bright colors of the grade node.
White balance expression
In the grade node whitepoint attribute, right click in the animation menu and select Edit expressions.
Now enter the following expressions in the r,g and b inputs:
whiteBalance.r/((whiteBalance.r+whiteBalance.g+whiteBalance.b)/3) whiteBalance.g/((whiteBalance.r+whiteBalance.g+whiteBalance.b)/3) whiteBalance.b/((whiteBalance.r+whiteBalance.g+whiteBalance.b)/3)
This simple code will always avarage your values to 1 and keep your image luminance.
As you can see we no longer have the luminance issue, try to pick a different area of the image to set the white balance.