LAYER MASKS EXPLAINED
They’re the key to all kinds of incredible composites, so it pays to know how they work...
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MAKING A MASK
To make a mask, we can either go to Layer > Layer Mask > Reveal All/Hide All, or click the Add Mask icon at the bottom of the Layers Panel. We can also Alt-click the icon to add a full black mask. If we first have an active ‘marching ants’ selection, that will be converted into a mask and any areas outside will be hidden.