6. The Tools in the Toolbox / 6.3 Tools for Image Layers
The Border Matting tool is used to create cut-out masks for semi-transparent areas like hair. Usually you first create a basic selection with another tool - i.e. the Quick Selection tool or the Auto Mask - and enhance that with the Border Matting tool in the critical areas.
If you select the Border Matting tool and there is already a selection, the image will be marked with different colors depending on the existing mask values:
You can edit the existing marks with the subtools of the Border Matting tool:
If you activate Edit Soft Edge in the Tool Settings the otherwise orange areas will become transparent. This means the mask values will be recreated there, too.
Apply recalculates the new mask values. After that you will still see the color marks. You will see the normal mask and lasso view only after switching to another tool. You can nevertheless examine the result directly by using the Magnifier (see chapter 4.29).
Note: It might be quite laborious to create good color marks. Therefore, the Border Matting tool is saving your marks along with the image. This way you don't have to create everything in one single step. The marks will only be deleted under one of the following conditions:
You can postprocess the selection with Extract selection (chapter 7.6.31).