Understanding Layer mask

How the layer masks works:

• Black: eliminate pixels
• White: replace pixels
• Grayscale colors: reduce pixel opacity

Let’s suppose you’re working on a complex composition with lots of layers. At the end of the process you decide that you’ve erased too much of an object. How to repair? If you have used the eraser tool there’s no way, while if you used a layer mask, simply grab a white brush and modify the image until you’re satisfied.

So here is a basic definition: the layer mask is a tool that allow you to eliminate and replace pixels of a layer at any time.

Exercise 1: create the til-shift photography effect using masks

Download this beautiful photo of Prague and open it in Photoshop.

Duplicate the layer by pressing Ctrl+J (or go to Layer>Duplicate layer).

Now go to filter>Blur>Gaussian blur and enter a value around 10px:

At this point we have two layer: the bottom one which is the original layer, and the upper one which is blurred. To create the til-shift effect we have to remove the blurred effect from a specific area – the one you want to emphasize. So create a layer mask:

Grab a black soft brush (reduce hardness to 0%) and start painting over the bridge. Painting over the mask using a black brush we remove that area. In this way an area of the below layer will reappear:

Here is the til-shift effect! In case you’re not satisfied with the result. you can always use the white brush to replace the pixels.

Exercise 2: working with gradients

There’s another tool that can be used combined with layers masks: the Gradient tool (G). Download this picture of a flower and open it in Photoshop.

Duplicate the flower’s layer (ctrl+J) and desaturate it by going to Image>Adjustments>Desaturate.

Create a layer mask. Set black as foreground color and white as background. Then grab the gradient tool (G), click on the left edge of the canvas, drag till the right one and release. The final result gently goes from the colored area (eliminated from the top layer using the gradient tool) to the black/white one.

This technique, that can result not so useful, is often used in web and icon design to create gradients going from white to transparent.

Exercise 3: Masks and selections

Masks can work as separate layers because what you make on them won’t affect directly the layer masked, but only the mask. Another powerful feature derives from the combination between masks and selections.

Download this beautiful portrait of a woman and open it in Photoshop.

Unlock the background layer. Grab the Polygonal lasso tool and make a rough selection of the face:

Press the layer mask button. The face will be isolated from the background.

Tip: if you want to eliminate the selection using masks, instead of isolate it, hold down “alt” on your keyboard while pressing the mask button.

After desaturated the lady’s face by pressing shift+ctrl+U, create a new layer and move it below the lady’s one. Grab the Paint bucket tool and fill the layer with white.

Select the lady’s layer and fo to filter>Artistic>Dry brush and enter the following settings:

• Brush size: 7
• Brush detail: 5
• Texture: 1

Press OK to apply the filter:

Now select the mask thumbnail. We will play a bit with face contours using dry paint brushes. You can download our Dry Paint strokes brushes here.  Once obtained the .abr file, grab the brush tool (B), then in the tool options bar (on top) open the brush window and, once opened, click on the little arrow on top-right. In the menu that appears select “load brushes”. Here select the .abr file and load it.

With black as foreground color and the mask still selected, grab a brush from the new set and paint over the outline of lady’s face.

Here is my result:

Finally create a third layer and put it between the lady’s one and the background. Grab the brush tool and paint around the lady’s face. This time dry paint strokes won’t be used to eliminate some areas from lady’s face, but to enhance it.

And here is the nice result of this brief tutorial:

I hope you have understood how masks work following these brief tutorials. I’m going to publish other tutorials for beginners, so stay tuned! In case you have suggestions on a specific Photoshop feature you want to learn, use the comments below.