Blending Different Exposures

Layer masks make it possible to combine different exposures of the same image. This is especially useful when you have an image that has deep shadows as well as bright highlights.

Figure 4.21. The source images (examples A and B) and the finished composition (example C).

This picture of Bryce Canyon contains a very dark foreground shape. The image was scanned from a transparency, and no matter how I tweaked the scanner software, I got one of two unacceptable results: if the scanner software was adjusted to capture the bright values of the background rock and the tree, the foreground shape became a dark blob that held no detail, or if the scanner software was adjusted to capture the foreground, the background became overexposed. The solutions: scan the image twice; or if working with a Camera RAW file, open two versions of the imageone that captures highlight detail, the other that captures shadow detail.

1.	Open the source images, Bryce Bright and Bryce Dark.
2.	Using the Move tool (v) drag the foreground (bright) image onto the background (dark) image, holding down the Shift key to align the layers.
3.	On the top layer make a selection of the rock shape on the leftI used the Pen tool, then converted the path into a selection, but the Magnetic Lasso also works.
4.	Click Add Layer Mask, at the bottom of the Layers palette, to convert the selection into a mask, revealing the rock and letting the tree and background rock from the layer beneath show through.
5.	As a finishing touch to feather the transition between the two layers, apply a 1.5-pixel Gaussian Blur to the layer mask.

Figure 4.22. The Layers palette showing how the image is constructed.