By rsinmadrid

If you have successfully used layer masks in Photoshop, move along--this tutorial is not for you. Rather, it is directed at people who have never been able to get started at all because they have stumbled on the basic mechanics of creating and modifying a mask. Some highly accomplished photographers have had difficulty understanding these concepts, so I thought a Chapter 0 primer might be helpful. My only goal is to clarify the differences between the layer content, the layer mask and the layer mask display.

A mask makes part of a layer transparent. In a portrait, you might want to sharpen only certain portions of the subject. By using a sharpened layer with a mask on top of an unsharpened layer, you can sharpen only once then experiment with changing the mask to control which areas appear sharpened. While you can accomplish the same thing using a combination of the eraser and history brush, masks have many intermediate and advanced applications that the eraser cannot do at all.

To begin, I created an image consisting of two layers, one yellow and one blue. The blue layer is on top of the yellow, so you cannot see the yellow at all, even though it is there.

The blue layer is active (as shown by the highlight in the layers palette). By clicking on the icon circled in red, I added a layer mask to the blue layer.

CLICK ON THE IMAGE TO SEE A LARGER VERSION.

By rsinmadrid

If you have successfully used layer masks in Photoshop, move along--this tutorial is not for you. Rather, it is directed at people who have never been able to get started at all because they have stumbled on the basic mechanics of creating and modifying a mask. Some highly accomplished photographers have had difficulty understanding these concepts, so I thought a Chapter 0 primer might be helpful. My only goal is to clarify the differences between the layer content, the layer mask and the layer mask display.

A mask makes part of a layer transparent. In a portrait, you might want to sharpen only certain portions of the subject. By using a sharpened layer with a mask on top of an unsharpened layer, you can sharpen only once then experiment with changing the mask to control which areas appear sharpened. While you can accomplish the same thing using a combination of the eraser and history brush, masks have many intermediate and advanced applications that the eraser cannot do at all.

To begin, I created an image consisting of two layers, one yellow and one blue. The blue layer is on top of the yellow, so you cannot see the yellow at all, even though it is there.

The blue layer is active (as shown by the highlight in the layers palette). By clicking on the icon circled in red, I added a layer mask to the blue layer.

CLICK ON THE IMAGE TO SEE A LARGER VERSION.