You can see our original image is too dark, but sometimes exposure problems are not this obvious. The best way to know for sure: check the histogram–a graphical representation of tonal values (Enhance > Adjust Brightness/Contrast > Levels).
Now zoom in on a detail such as a tree branch or strand of hair and see if the edges appear crisp and clearly defined. If the detail is a bit fuzzy, avoid the Sharpen filter–it just increases overall contrast and often introduces noise. Instead, use the more precise Unsharp Mask (Filters> Sharpen> Unsharp Mask), which only sharpens select areas. Keep the Amount slider at 150 percent and adjust the Radius and Threshold sliders. Radius controls how much sharpening is applied, Threshold controls where (a higher Threshold means fewer areas are affected). Larger images require bigger adjustments, but beware: even here, too much sharpening will add noise.
The resultant Width and Height are the maximum size at which you can make a film-quality print.
Once you’ve cropped your image and decided what size photo you want to print, open Image > Resize > Image Size, deselect the Resample Image box and change the number in the Resolution box to read 266 pixels per inch.
Noise and Less Noise
Now zoom in to at least 100 percent and look for blotchiness (noise) in what should be a solid area of color. If it’s minor, use Despeckle (Filters > Noise > Despeckle), which slightly blurs the entire image. For more precise control, pick up nik multimedia’s Dfine plug-in ($100; nikmultimedia.com).
After you’ve fixed the exposure you can determine if your image is too warm (red), cold (blue) or yellowy green (like the shot above right). Go back into Levels and use the pull-down menu to bring up a histogram for each color (starting with the most pronounced), then adjust the sliders just like you did for Exposure. Overcorrect and then ease the slider back, but be gentle: Adjusting one color affects other colors as well (increasing red removes cyan, adding blue removes yellow, and more green means less magenta).