Quite often when masking in Photoshop, you might find a fine halo of darker or lighter pixels around your mask. This might become really obvious when you try to place this masked layer against a high-contrast background. There has been a lot said and written about cleaning up edges, but here’s one surefire method. Command-click (PC: Ctrl-click) on the layer mask thumbnail in the Layers panel to select the pixels. Choose Select>Modify Contract, enter 1 or 2 pixels, and click OK. Choose Select>Inverse to invert the selection. Choose Select>Modify>Feather, enter 1 pixel, and click OK. Press X until your Foreground color is white. Press the Delete (PC: Backspace) key, and the fringe will disappear.
This tip originally published in the Photoshop Tips column by Colin Smith, in the November, 2016 issue of Photoshop User magazine.