|Photoshop Luminance-Equalization Tutorial
Tutorial by Jeremy Birn
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Bad exposure in the original shot (below left) hides the giant tree's textural root structure in shadows and washes-out the sunlit areas of the forest. This tutorial shows a powerful luminance-equalization technique, which can enhance both the underexposed and overexposed areas of an image, without reducing the overall contrast of the shot, and without any manual selection of regions. The Equalized result (below right) only took 4 quick steps to improve the shot. The 4 steps are illustrated below.
1. In the Layers window, drag the Background layer down
2. With the new layer active, press Ctrl-i
3. Choose Filter > Blur > Guassian Blur from the menu.
4. In the Layers window, change the Background Copy
That's it! Your image will now look like the Equalized image above (the right side of the comparison at the top of this page.) The Soft Light blending mode essentially performs burning and dodging functions onto the background layer for you, guided by the values of the inverted layer. The blurring of the Soft Light layer prevents it from neutralizing local detail or graying the image, so it only corrects for the overly dark or bright areas.
You could stop here, but this is also a terrific starting-point for other adjustments:
The next page shows how this technique is applied in creating seamlessly tiling texture maps for 3D graphics.
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