Friday, July 20, 2007
Must-Know Image Enhancements
How to change, improve and rescue exposures
To illustrate the enhancements, I'll use some digital files that I took on a family vacation in the Galápagos in August 2006. I mention the "family" part of the trip to illustrate the point that it's possible to have fun taking pictures while on a family trip! Okay, let's visit The Enchanted Islands, as Charles Darwin called the Galápagos.
(Image > Adjustments > Brightness/Contrast)
When a picture can be improved by increasing the contrast, I often use the Contrast control in Brightness/Contrast. That's what I did to this picture of a Sally Lightfoot crab, which I photographed in the low-contrast lighting of an overcast morning.
(Image > Adjustments > Levels)
Levels is one of the most basic, yet important enhancements you can apply to your pictures. That's what I used to enhance the picture of a mother sea lion nursing her pup.
In the Levels dialog box, you see the histogram for the image. The histogram, which resembles a mountain range, shows the distribution of the brightness levels in the picture, with the light areas on the right and the dark areas on the left. The higher the area of the "mountain," the more light or dark areas there are in the image. The basic concept is to move the Highlight triangle inside the right side of the mountain range and then move the Shadow triangle inside the left side of the mountain range. The result is that the Levels of the image are spread out. If you were to open the Levels dialog box after making those adjustments, you'd see that the mountain range would now extend to the right and left side of the histogram.
In a few seconds, I've improved the color, contrast, brightness and saturation of the scene using only Levels.
You also can use the Eyedropper tools in the Levels dialog box to set the White point (right Eyedropper), the Black point (left Eyedropper) and the Gray point (middle Eyedropper). Simply click on the appropriate Eyedropper, and then click on the area of the picture that you feel should be white, black and gray, and the points are set automatically, producing an improved image—if you select the points correctly.
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