In this short tutorial you will learn what layer masks are and how to utilize them for working faster and more efficiently in Photoshop.
Lets consider what masks do: They hide or show things. Masks in photoshop work the same way: they can hide or show parts of images. In general filling a layer mask with black hides a part of the image. Filling a layer mask with white shows a part of an image. Filling the mask with gray will show the part of the image with varying opacity based on how light or dar the gray is.
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