Masks can quickly get confusing in ON1 Photo RAW. It’s not the tools themselves which are confusing, but the fact they can be used in three different places: Local adjustments: These are applied to the image as a whole in their own ‘Local’ panel. In other words, they are not associated with any specific layers […]
Adjustments made only to specific areas in a photo, not the whole picture. You pick out the areas you want to adjust with selections, masks or brush tools.
This step-by-step editing walkthrough shows a number of DxO PhotoLab tools in action, principally the Local Adjustment tools, including the Graduated Filter and Control Point tools.