We now want to replace that sky with a completely different image. Use Load To Layer to open a file of a nice new sky, and move this new layer behind Layer 1. And lo! It is done (Figure 5). Be careful not to get carried away--it is England, remember--so there’s no point in making the sky too blue.

Here’s a neat trick to produce a startling and colorful composite from one photograph and a couple of textures. You can do this with any three images, and it takes just seconds at any size or resolution. Open the main image (Figure 6), and then from the Masking menu click Luma, and then Make Mask (0% to100%). This makes a semitransparent user mask based upon the brightness levels contained within the image, where dark areas are rendered transparent and light areas opaque (or vice versa). The excellent natural lighting in our sample image perfectly lends itself to luminance keying.

From the Load To Layer dialog, select the first texture file (Figure 7, a scan of a manipulated Polaroid), then click Add To Layer. You can either stretch the incoming texture to fit the shape of the canvas, or you can maintain its aspect ratio. We’ve given the first texture a color correction (see Step 2) to enhance the reds and yellows. It will key through the light areas of the main image, revealing the infinite background behind.

8 Master of the Elements

Open the second texture file (Figure 8a), click New Layer for your destination, and place it behind Layer 1 by dragging its position in the Layer List (Figure N).