Trim Pass

A 'trim pass' refers to the process of adapting the colour grade to a smaller colour space. For example, you might grade in HDR, then trim it down to P3 theatrical, and finally to Rec. 709.

Sometimes, people start in a smaller colour space and 'trim' up to a larger one. For instance, grading in P3 theatrical, expanding to HDR, and then trimming to Rec. 709.

The term 'trim' traditionally implies reducing or making something smaller, so technically, it doesn’t perfectly apply when moving to a larger space, but it's still commonly used.