Layer Masks – Digital Photography Tip of the Week

Both Adobe Photoshop and Adobe Photoshop Elements 5.0 are great tools that offer precise control over your photographs. Back in the days when I printed my own black and white photographs in my basement darkroom, I used tools for both burning and dodging (adding or holding back exposure) specific parts of my photos. Today’s photo editors offer similiar tools but we with more precision. Layer masks are one of the tools that provide that precision.

A layer mask is a type of selection that maps which pixels will be affected by the modifications to the current layer. The advantage to using a layer mask instead of a normal selection is that is easily editable which allows you to modify the selection later on. Adobe Photoshop CS2 has full support for layer masks while Photoshop Elements only supports them on Adjustment and Fill layers. Layer masks can be edited by painted them. Portions of the mask that are painted black will not be affected while portions that are painted white will be. You can also use shades of gray to adjust the degree of adjustment. Before we begin with an image, let’s get acquainted with a layer from our image.

From left to right, the first icon tells us this layer is visible in the image (not hidden). The second icon indicates what kind of layer this is if it is an adjustment layer or will display a preview of the layer if contains image data. The third icon identifies whether or not our layer mask is linked to the actual layer. If it is not linked, the two pieces may be moved separately. The selected layer portion will be outlined when they are not linked. The next icon is a preview of our layer mask. This particular adjustment layer will modify the entire image with the exception of the subject in the image. Finally, the name of our layer. To add a layer mask to an image layer, press the layer mask button at the bottom of the layer palette .

Now lets start with the following image, a portrait of my friend Dave shot in a dark alley with only the overhead streetlight for illumination.

Original Image

Through a series of adjustment layers and layer masks, we will transform this flat image with poor colour into a nice black and white photograph. As I mentioned two weeks ago, my first adjustment is to set my white and black points using a levels adjustment layer. Because this layer will affect the entire image, I have not modified the default layer mask that accompanies adjustment layers, it is all white. Next, using a Channel Mixer adjustment layer, I converted the image to black and white and followed that with a color balance adjustment layer for more precise control of how the colors were translated into black and white. Again, both of these layers were applied to the entire image and so the layer mask is completely white.

Final image with all layer masks

I then began to add more adjustment layers to modify selected portions of the image. I used a curve adjustment layer for each of the subsequent modifications to this photo. I slightly darkened the outside of the image. This causes the viewer to focus in on the subject. I then created a new curves adjustment layer and with the paint bucket, filled the entire image in with black (not affected). Switching to a brush and changing my foreground colour to white, I then painted over the pants. With my selection complete, I was able to adjust the layer until I was happy with the look. I used the same process to lighten the shadow that fell on his face, then again to lighten the entire face. selected everything in the image except for Dave and increased the contrast of the image until I liked the result.

In this image below, I have turned of the adjustment layer where I modified the pants off so that you can see the difference. Note that the only the only piece of the image that is different is the pants.

Layer masks allow you to make non destructive edits to your image. These non destructive edits enable you to make changes to your image after without degrading the quality of the source file. The only time in the editing process that any pixels were actually modified was at the end when I saved the image to a JPG file. I can turn off all of the adjustment layers I have created and my original layer will remain unchanged from the point I first opened it.

Knowing how to maximize the quality of your image by using all of the tools available to you can help you create better photographs. With the help of layer masks, you can make multiple edits to your image, but be comfortable knowing you can change your mind later.

Until next week, happy shooting.

Comments 1

  • Thank you very much for the tutorial. I had not understood layers before. Now I think I will be able to do sum more things to make the pictures more like I think I saw them when I originally took the picture.

    Please continue these lessons, they are very helpful.

Leave a Reply

%d bloggers like this: