In Adobe Photoshop, you can make temporary masks, called quick masks. Masks let you isolate and protect parts of an image. When you create a mask based on a selection, the area not selected is masked or protected from editing.
Creating a quick mask
1. Open the image you want to make a selection on.
Sometimes you can make a large chunk of a selection by using the magic wand to begin with.
3. Click anywhere on the dress to begin the selection process.
4. To add to the selection, hold down Shift whilst clicking with the magic wand to add to the selection.
The dress is still only partly selected. Now we’re going to add to this selection using a quick mask.
6. Select the Quick Mask mode button () in the toolbox. By default, you work in Standard mode. When you click on the Quick Mask button, you will work in Quick Mask mode. If you click this button again you will go back to standard mode.
In Quick Mask mode, a red overlay (known as rubylith) appears, to mask and protect the area outside the selection.
Editing a quick mask
Now we need to refine the selection of the dress by adding to or erasing parts of the masked area. We do this by using the brush tool to make changes to your quick mask. The advantage of editing your selection as a mask is that you can use almost any tool or filter to modify the mask.
In Quick Mask mode, Photoshop automatically defaults to Grayscale mode. The foreground colour defaults to black, and the background colour defaults to white. When using a painting or editing tool in Quick Mask mode, keep in mind:
- Painting with white erases the mask (the red overlay) and increases the selected area.
- Painting with black adds to the mask (the red overlay) and decreases the selected area.
Adding to a selection by erasing masked areas
Start by painting with white to increase the selected area within the dress. This erases some of the mask.
3. In the tool options bar, make sure that the mode is Normal. Then click the arrow to display the Brushes pop-up palette, and select a medium-sized brush.
4. Using the brush tool, begin painting over the red areas within the dress. As you paint with white, the red areas are erased.
Don’t worry if you paint outside the outline of the dress. You can make adjustments later by masking areas of the image as needed.
5. Continue painting with white to erase all of the mask (red) in the dress. As you work, switch back and forth between Quick Mask mode and Standard mode to see how painting in the mask alters the selected area.
Notice that the selection border has increased, selecting more of the dress.
7. If necessary, zoom out so that you can see the entire image.
Subtracting from a selection by adding masked areas
If you’ve erased the mask beyond the edges of the dress, part of the background is included in the selection, so you need to return to Quick Mask mode and restore the mask to those edge areas by painting with black.
2. To make the foreground colour black, select the Switch Foreground and Background Colours icon () , or press X on the keyboard. Make sure that the black colour box now appears on top. Remember that painting with black will add to the red overlay.
3. Choose a brush from the Brush pop-up palette. Select a small brush to refine the edges of the selection.
4. Now paint with black to restore the mask (the red overlay) to any of the background area that is still unprotected. Continue working until only the area inside the dress remains unmasked and you are completely satisfied with your mask selection.
5. In the toolbox, switch to Standard mode to view your final dress selection, and continue working this way till you have the selection the way you want it.
I love the quick mask because it allows you to create a very precise selection using familiar and easy to use tools such as the paint brush. Have you made selections using the quick mask before? Do you find it useful or maybe too time-consuming?