You can specify a gamma scale factor for each bit run in Mezintel Gamma (version 22.00.061 ^[1]) using a new built-in tool that helps you derive scale factors.
You can enter a scaling factor if you know it, otherwise, if you are unsure then you can calculate or find it from the Bit Runs window:

• In the Scale section under the bit run you want, double-click the value box for Gamma Scale Factor
  → The Get Scale Factor window opens

You may also click the … button to open up Get Scale Factor window.