Understanding Masks

Masks are an infinitely useful tool to master. They allow you to make changes to photos and images quickly and easily in a totally non-destructive way. This is why masks are applied automatically when you add an adjustment layer. Confused? Don't be. Masks are in fact extremely easy to use. We'll show you how to get the best of masks in this tutorial by creating a photo montage.

• Create a mask from selection.

• Edit a mask.

In this tutorial, we will create a photo montage using three photos. We have provided the project file for you to use.

• Locate the mask.spp file and click Open.
  
  The image opens in the workspace.

If you look at the Layers tab, you'll see that this project contains three layers. Each layer contains a different image.

To create our montage, we need to erase parts of the top images to reveal the background. However, if we did this using the Standard Eraser, it would be really difficult to edit the image if we change our mind or make a mistake. This is where masks come in. Masks can be used to hide parts of an image (or effect) while revealing another part. Masks are easy to use and what's more, they make it really easy to change your mind! Let's get started.

You can add a blank, reveal all mask (white thumbnail) by simply clicking   Add Layer Mask on the Layers tab, however, it's often much easier to create one from a selection. You can always edit the mask later.

To create a mask from a standard selection:

1. On the Layers tab, select the 'Man' layer.

2. On the Tools toolbar, on the Selection Tools flyout, click the  Ellipse Selection Tool and on the context toolbar, set the Feather to 0.

3. Drag the selection around the head and shoulders of the man. If necessary, move the selection into position.
   
   
   
   Let's feather the selection a little.

4. On the context toolbar, click Modify Selection...

5. In the dialog:

6. Click White Matte in the Preview drop-down list. This will show us what part of the picture will be protected when we create the mask.
   
   

7. Drag the Feather slider to the right until you get an effect you like—a feather of 45 works well.
   
   

8. Click OK. The selection is updated.

6. On the Layers tab, click  Add Layer Mask. A mask thumbnail is added to the layer.
   
   
   
   On the page, the selected area remains, whereas the area outside of the selection is hidden.
   
   

7. By default, when you click the  Add Layer Mask button, the selection is revealed. If there is no selection in place, you will apply a Reveal All mask (white mask thumbnail). If you want the opposite behavior, press the Alt key while clicking the  Add Layer Mask button. This will apply a Hide All (black mask thumbnail) or Hide Selection mask.

Our first mask is complete. If you temporarily hide the 'Ball and racquet' layer, you'll see that we've created a subtle edge to our photo montage. (Don't forget to make the 'Ball and racquet' layer visible again before attempting the next step.)

• You can view your mask at any time by clicking Layers>Mask>View Mask or by pressing the Alt key and clicking on the mask thumbnail on the Layers tab.

To create the second mask, we're going to use the  Brush Selection Tool. Before we start, if your previous selection is still active, press Ctrl + D to deselect it.

To create a mask from a selection II:

1. On the Layers tab, select the 'Ball and racquet' layer.

2. On the Tools toolbar, click the  Brush Selection Tool and on the Brush Tip tab, select the 64 pixel hard (Round Hard07) brush.

3. Paint over the ball and racquet to create a selection around the objects. Don't worry about being too accurate, we'll correct any mistakes later.
   
   

4. On the context toolbar, click Modify Selection...

5. In the dialog:

6. Click White Matte in the Preview drop-down list. This will show us what part of the picture will be protected when we create the mask.

7. Set the Feather to around 5 pixels.
   
   Click OK. The selection is updated.

8. On the Layers tab, click  Add Layer Mask.
   
   
   
   The mask is added to the layer and the background is revealed.
   
   

We're almost finished, however, if your image is like ours, you'll notice that there is a little too much fade around the edge of the ball and racquet. We can easily fix this by editing the mask. First of all, we need to remove the current selection. Either press Ctrl + D or go to Select > Deselect.

To edit a mask:

1. On the Layers tab, the 'Ball and racquet' mask thumbnail should be selected (surrounded by a white outline). If not, click once to select it.

2. On the Color tab, notice that the colors have automatically changed to black and white. The foreground swatch should already be white, if not, set it to white now.

3. On the Tools toolbar, click the  Paintbrush Tool and on the Brush Tip tab, select the 64 pixel soft brush.

4. Carefully start to paint around the edges of the racquet and ball. If you make a mistake, switch the foreground back to black and paint over the mistake to reapply the mask. Also, fill in any holes that may have been in your selection.
   
   
   
   Next, we'll blend the left edge of the photo into the background. We'll do this with the gradient tool.

5. On the Tools toolbar, on the Selection Tools flyout, click the  Rectangle Selection Tool and on the context toolbar, set the Feather to 0.

6. Click and drag on the lower-left portion of the image to create a small selection, taking care to ensure that it touches the bottom edge of the image.
   
   

7. On the Tools toolbar, in the Fill flyout, click the  Gradient Fill Tool. On the context toolbar, the gradient should be set as a black to white linear gradient. (If not, click the gradient swatch and then in the dialog, click the first gradient swatch.)

8. Starting in the center, drag the gradient from left to right.
   
   
   
   On release, the gradient is applied to the selection. If you are happy with the gradient, press Ctrl + D to deselect.
   
   

9. You'll notice that there is now a hard line just above the shadow. Click the  Paintbrush Tool and on the Color tab, switch the foreground to black.

10. Carefully paint over the edge to soften it.

That's it! Your photo montage is complete!