In the first part of this series,I explained the basic principles behind layer masks, and how to apply them to hide or enhance an area of an image. Now, let’s take layer masks a bit further.

For the next example, we’ll use a common scenario: You apply an S-curve to increase contrast in the midtones. While this change bene
ts the image as a whole, it negatively impacts a small portion of the photo, such as the foreground ice in this photo.



Select the Brush tool from the Toolbox, choose Black as the foreground color, and reduce the brush opacity to 40 to 60 percent; this allows you to paint out the contrast in the negatively impacted area. This image shows a black overlay on the painted areas of the mask.



Note: When painting on the layer mask, you should not see the addition of black or white; you will see only the adjustment layer’s change added or subtracted from the photo.

The
nished photo shows the improved contrast through the midtones and the detail in the ice returned.



Tips for Working with the Brush Tool
Many of the layer masks you’ll use are so crude, you won’t need to create a selection before building your mask. For these masks, you’ll use the Brush tool to target a speci
c region of your photo. Since you’ll be spending a lot of time using the Brush tool, I’ll arm you with several tips for using the tool when creating masks.

Although Photoshop comes with dozens of brushes in all shapes, sizes, and textures, you really need to use only two brushes for your work: a soft-edged brush for gently applying color and contrast corrections and a hard-edged brush for making changes along well-de
ned edges or lines.

The brush size, shape, and intensity are determined by three controls in the Brush Preset picker and Options bar: Brush size, Hardness, and Opacity. Th e Brush Preset picker is displayed only when the Brush tool is selected, so be sure you’ve selected the Brush tool.


The Hardness slider determines whether the paint strokes have soft or hard edges. Both brush strokes above use a 60-pixel brush, but the top stroke uses a Hardness setting of 0, while the bottom uses a Hardness setting of 100.

The Master Diameter slider controls brush size (in pixels). It can be difficult to select an appropriately sized brush using the Master Diameter slider because the effective brush size is relative to the overall image size. This means a 100 px brush will appear tiny when working on a 3000-pixel–wide digital photo and will appear quite large when working on a small Web graphic. Instead of setting your brush size in the Brush Preset picker, set your brush hardness and use keyboard shortcuts.

The Hardness slider setting determines how well de
ned the edges of a brush stroke are. A low Hardness setting creates a soft brush, ideal for making subtle changes to a mask. A high Hardness setting is often used in compositing, where a precise edge is essential.

Tip: Use keyboard shortcuts. The easiest way to choose the correct brush size for all your painting needs is to hover your cursor over the image you’ll be painting on and use the right bracket (]) and left bracket ([) keys to increase or decrease the brush size, respectively. This allows you to set your brush size visually relative to your photo.

The third important brush attribute is the brush Opacity, controlled by the Opacity slider in the Options bar.



Reducing the opacity helps your brushstrokes blend in your changes more naturally. When applying subtle contrast or color changes, set your brush Opacity between 40 and 60 percent with a soft brush. This masks any imperfections in your brush strokes and allows you to build up your correction in several steps.


The topmost brush stroke uses a soft brush set to 100 percent Opacity. The remaining three strokes show the effect of painting using multiple passes at a decreased Opacity setting, from a single pass at 50 percent, to four passes at 50 percent.

Tip: You can adjust the brush Opacity using the number keys on your keyboard when the Brush tool is active. Press 5 for 50 percent, 9 for 90 percent, and so on. Pressing 0 (zero) will return the brush to 100 percent.

Now that you feel comfortable using Photoshop’s brushes, it’s time to put your newfound skills to work modifying layer masks with the Brush tool.

Tips for Working with Masks
To review what we’ve covered so far, every Curves, Levels, or Hue/Saturation adjustment layer is accompanied by a white rectangle in the Layers palette. This rectangle is a layer mask for the adjustment layer. Since the layer mask is
lled with white by default, any changes you make to the adjustment layer are applied to the entire image.

Using the Brush tools on a layer mask, you can isolate your changes to a speci
c region of the image without affecting the rest of the image. Furthermore, you can adjust, scale, blur, and sharpen the layer mask to achieve very exacting results. Layer masks give you exibility unmatched by traditional darkroom techniques.

To help you get up to speed quickly with layer masks, I’ve compiled a list of helpful tips. Use these to supplement the fundamental techniques discussed so far:

• When making a change adversely affecting one portion of an image, simply mask it out using the Brush tool and paint black on the layer mask.

• When you need to apply your correction to a small portion of the image, invert the layer mask from white to black by pressing cmd-i (Mac) or ctrl-i (Windows). Then brush in your correction by painting white on the layer mask.

• Use any of the selection tools to select a portion of the image, and then create your adjustment layer. Your selection will convert automatically to a mask and be applied to the new adjustment layer.

• Copy layer masks from one layer to another by holding down the option (Mac) or alt (Windows) key while clicking and dragging the layer mask to the new layer. When prompted, click Yes to replace the existing layer mask.

• Use the backslash (\) key to show your mask as a colored overlay on the image. The default color is red, but you can change this by double-clicking the layer mask thumbnail in the Layers palette.

Tip: When using the backslash shortcut, be advised that Photoshop sometimes switches your foreground and background colors as it toggles between the mask preview and the original image.

Temporarily disable the layer mask by holding the shift key and clicking the layer mask thumbnail in the Layers palette. I frequently use this to locate errant brush strokes or halos around the masked areas while zoomed in to a detailed section of the photo.

We’ve now covered the basics for working with layer masks and adjustment layers. For more on this subject, see Perfect Digital Photography Chapters 15 and 16, or go to this online tutorial.

This article is excerpted from the newly-published Perfect Digital Photography, Second Edition, by Olympus Visionaries Jay Kinghorn and Jay Dickman (McGraw Hill), availablehere.