The Magic Eraser allows you to easily refine masks by erasing areas of similar colour, tone and texture. Simply erase a line or any other small selection within the masked area to see the effects of the Magic Eraser.
By default, the Magic Eraser tool can be found in the Layers tool, in the Toolbar, or by pressing E on your keyboard.
Similar to other cursor tools with identical shortcuts, you can switch between them by using Shift + E. If you prefer, you can set a custom shortcut by going to Edit > Edit Keyboard Shortcuts...
1. Go to the Layers tool or Toolbar
2. Select the Magic Eraser tool.
3. Right-click with the Magic Eraser tool selected and you'll see the settings below.
Size - Changes the size of the eraser
Opacity - Controls the opacity at which the eraser will operate, i.e. How much of the mask remains once it is erased
Tolerance - Defines the range of tonality the eraser will cover. A low Tolerance will restrict erasing to similar tones, while a high Tolerance will pick up a wider range of tones
Refine Edge - affects the edge of a mask that will be erased. A low Refine Edge value will result in a hard, defined edge, while a higher Refine Edge value will render a mask with a softer fall-off into the surroundings.
Sample Entire Photo - determines if erasing a mask will be restricted by its edges. If enabled, the erase action considers the entire tonal range of the image and not just the mask that has been drawn
Resizing and changing parameters of the Magic Eraser
Use similar shortcut actions as the regular Adjustment Brush:
Size: Ctrl + Opt + left-click and horizontal drag (right/left)
Tolerance: Ctrl + Opt + left-click and vertical drag (up/down)
Opacity: Shift + Ctrl + Opt + left-click and horizontal drag (right/left)
Refine Edge: Shift + Ctrl + Opt + left-click and vertical drag (up/down)
Size: Alt + right-click and horizontal drag (right/left)
Tolerance: Alt + right-click and vertical drag (up/down)
Opacity: Shift + right-click and horizontal drag (right/left)
Refine Edge: Shift + right-click and vertical drag (up/down)
Any adjustments made to the masked area will only show if mask visibility is set to 'Only Display Mask When Drawing' or 'Never Display Mask' - if you have selected 'Always Display Mask', the adjustments will only appear when a slider (such as Exposure) is adjusted.
You can quickly toggle between 'Always Display Mask' and 'Never Display Mask' by pressing the M key. It's also possible to click on the Mask Visibility icon, which is found in the Viewer Toolbar, where the same preferences can be changed.