A primary component of compositing is the assembling of different image elements and the subsequent positioning and scaling required to achieve the final desired composition. Assembling the image components consists of selecting them from their respective images. The selections are made using combinations of techniques from Chapters 3 and 4.
Because I'm often not sure exactly how I'll use selected image components in a project, I first like to assemble all of them into a kind of clip book. A clip book is just a single image consisting of a layer for each image component. This makes an image palette from which the various components can be copied and then pasted into the target composition.
Figure 7.1(a)
The background image is shown in
Figure 7.2(a).
There are two features worth noting in Figure 7.2. First, the Layers dialog shows that the new layer has been named Angel Fish to more easily identify it later. Second, the Angel Fish layer's boundaries (the yellow and black dashed line) are visible in the image window because it is the active layer in the image. The layer's boundaries can be toggled off by typing C-t in the image window. With respect to our composition, the first thing you might notice is that the angel fish seems too large for the background. This can be fixed by shrinking the angel fish or by enlarging the background. As already noted in Section 2.6.2, it is almost always preferable to shrink an image element that is too large rather than to enlarge the element that is too small. This is because enlarging an image requires interpolating pixel values, which introduces unpleasant image artifacts. Always avoid this--unless, of course, the artifacts are desirable as an artistic device.
Thus, our first task is to scale the Angel Fish layer to a more
fitting size for our scene. This can be done in two ways, either with
the Transform tool from the Toolbox or the Scale
Layer command found in the Layers menu.
Section 2.6.2 describes both. The Transform tool is used here because it is interactive and gives some
visual feedback to the scaling process. The Scaling option of the
Transform tool is invoked by double-clicking on the Transform tool icon in the Toolbox, which brings up the Tool
Options dialog. The Scaling option can then be selected from the
dialog, as shown in Figure 7.3(b).
Figure 7.3(a)
In scaling the Angel Fish layer, the aspect ratio has been preserved. This prevents the scaled layer from looking distorted. The aspect ratio can be maintained manually by watching the Scaling Information dialog and keeping it manually adjusted during the scaling process. The Scaling Information dialog provides interactive feedback about the X and Y Scale Ratios while the transform is being performed. The aspect ratio is preserved by keeping the X Scale Ratio equal to the Y Scale Ratio. Alternatively, the Scaling option of the Transform tool can be constrained to preserve aspect ratio by pressing the Control and Alt keys while scaling. In this example, the angel fish has been scaled to 60% of her original dimensions. In the compositing process, however, this might be undone an redone several times to achieve the desired effect in the final result.
When the scaling of the angel fish is complete, she can be
positioned using the Move tool. Her final location for this project is seen in
Figure 7.4.
The final procedure performed in this project adds an element of depth
to our composition. The idea is to make the sea horse's tail look as
if it is wrapped around a tree and to make the little red fish appear
as if it is peaking out from behind another. This is done with layer
masks (see Section 4.2). The
elements of the procedure are shown in
Figure 7.5.
Because the tree's boundaries can be seen, the Paintbrush tool can be used to paint away parts of the Sea Horse mask making the tree fully visible from behind. Figure 7.5(a) shows that this process has been started using a brush from the Brush Selection dialog and shown in Figure 7.5(c). The whole procedure is summarized in the following steps:
If too much of the layer mask is removed while painting, you can recover it by changing the Active Foreground Color to white by typing x in the image window and by painting over the erroneously removed parts of the mask. Close to the edge of the tree, it is probably worthwhile working with a smaller brush size in conjunction with the Airbrush tool, which is more effective at applying graded amounts of paint. See Section 4.5.1 for more details.
The result of applying layer masks to both the Sea Horse and the Red
Fish layers is shown in Figure 7.6.
The effects obtained with layer masks could have also been accomplished with selections applied in the image window. However, this would have required permanently cutting away parts of the Sea Horse and Red Fish layers. Alternatively, the layer masks used in conjunction with the painting tools simplified the work and produced a more robust solution. Because of the layer masks, nothing has been irrevocably lost in either the Sea Horse or Red Fish layers. Thus, these layers can be repositioned if need be--only the layer masks need be re-edited. This flexibility with positioning adjustments is not possible when using selections because the cut-away components are gone.
To summarize, this project reviewed cutting, pasting, scaling, and the positioning of layers for compositing. In addition, a simple application of layer masks was used to give our composition some illusion of depth. The next compositing project is more complicated because it makes use of the blending modes and the Curves tool.
