This article is part 2 in a series that explores useful techniques for creating surreal composite images in Photoshop CS4. In part 1 of this series, we gathered three stock images into one document, scaling various elements of the composite to fit together visually. For this article, we'll consider how we can mask away the extraneous parts of our source images, so that the remainder appears to be part of the original scene.
For the waterfall example, I started with the woman standing alongside the river and park bench. I needed to add her to the waterfall scene in a realistic way, so my three primary tasks were placing the woman into the scene, scaling her to fit the placement (both of which were discussed in part 1 of this series), and then masking away any extraneous areas from the original photo that would detract from the composite scene.
Having already chosen a placement and scale (foreground shoreline), I had a couple of masking choices. I could either integrate some of the grass and leafy material under the woman's feet, or I could try to hide everything in the scene except for her. I went with the latter choice so that I would have the option of placing her directly onto the rocks or shoreline, without having to mask and unmask the areas around her feet as I repositioned her.
To get started with my masks, I like to use the Quick Selection tool to make an approximate outline (see Figure 1). This method is fast and provides a good starting point.
Figure 1 There are many ways to create a layer mask for your subjects. For this subject, the Quick Select tool was used to generate an outline of the model's body.
For this image, I tapped W to activate the Quick Selection tool, and then sized the brush cursor down so that the cursor fit within the smallest part of the subject's body[md]her head.
Next, I placed the stylus on the tablet and slowly dragged the cursor around the periphery of the subject's body. In many cases, if you have a strong tonal contrast, as I did here, the entire subject is selected quickly with this technique.
Once you have a decent selection outline of your subject, it's easy to turn that selection into a layer mask. Click the target layer; then click the Add Layer Mask button at the bottom of the Layers panel (see Figure 2). This action automatically masks away the rest of the layer so that only the outlined region remains visible.
Figure 2 Creating layer masks from selections is a good way to get a quick start on the process, saving many brush strokes.
Perfecting the shape of a layer mask requires two separate steps. First, I generally use the Brush tool to paint around the edges of the subject with a combination of white (reveal masked area), black (hide visible area), and gray (partially reveal or hide a masked area), so that a precise and relatively smooth edge is created. As shown in Figure 3, I zoomed in to 300% and brushed along the edges of the subject's figure with a small white brush at about 70% hardness. The reason for this brushwork is that the final Quick Selection was hiding the outermost edges of the woman's clothing. Later in this procedure we'll uniformly shrink the selection (leaving only the woman visible) by using the Mask Edge function.
Figure 3 Use the Brush tool to perfect the shape of the layer mask that hides the extraneous material around the subject.
Brush hardness can be an important factor when tweaking a layer mask. As a general rule, it's rare that you'll use a brush with a 100% Hardness setting to create mask edges. Next time you're outside, pay attention to the edges of things in the distance. Cars, people, vegetation[md]do any of them appear to have perfectly defined edges (like an illustration)? Or is there a tiny bit of haze and softness in many cases? This slight degree of softness is what you're trying to mimic when masking your subject.
One new development for masking workflows in Photoshop CS4 is the Rotate tool. This tool allows you to rotate your image preview quickly, so that you don't have to brush along awkward diagonal edges. This feature makes it easy to brush around complex shapes with your stylus and tablet (see Figure 4).
Figure 4 The Rotate tool simplifies brushing around complex shapes when perfecting a mask.
To use the Rotate tool, hold down the R key, place the stylus on the tablet, and move right or left to rotate the preview. Once you've made your brush strokes and you want to move to a different orientation, just hold down R again and continue rotating, or tap Escape to remove the temporary rotation effect. If you prefer, you can use the Rotate Angle field in the Options bar to specify a numeric value for the rotation amount.
The final step in creating the masks for the woman and the Buddha figure in the example was to make a final correction by using the Refine Mask dialog. Make sure that the layer mask is selected in the Layers panel; then click the Mask Edge button on the Masks panel. This action opens the Refine Mask dialog, give you precise control over the entire boundary of the mask shape (see Figure 5).
Figure 5 The Refine Mask dialog (accessed from the oddly named Mask Edge button in the Masks panel) is a great way to make uniform adjustments to the shape of the entire mask contour.
My goal was to "shrink" the mask a little bit so that it stopped right at the edge of the woman's hair and clothes. I accomplished this using a combination of the Radius, Contrast, and Contract/Expand sliders, along with the "mask on black" and "mask on white" options. Generally I keep the Smooth and Feather settings at low values when I'm trying to maintain a degree of realism. Sometimes you may find that most of your mask looks perfect but one area still has extra image data showing through, or perhaps a bit too much taken away. For these cases, go back and touch up the mask with the Brush tool; then try again.
Figure 6 shows how the woman looks as she relates to the rest of the scene after the final masking tweaks were all applied.
Figure 6 Creating precise layer masks around the images you've placed into your scene is crucial to creating the beginning of a believable look.
As I continued working with this image, I masked away the white areas behind the Buddha (seen in the other image) using similar techniques, except that in this case I selected all the pure white pixels by using the Magic Wand tool and a low Tolerance value. Sometimes you only need the most basic tools to get a good head start on your layer masks!