Most of the sliders in the Adjust palette affect the histogram in some way. But where do you begin?
Here's a general suggestion: Make exposure adjustments first. In the simplest terms, the Exposure slider makes your picture lighter when you move it to the right and darker when you move it to the left.
Its effects differ slightly depending on which file format a photo has:
Watch the data on the histogram as you move the Exposure slider. Make sure you don't wind up shoving any of the "mountain peaks" beyond the edges of the Histogram box. If that happens, you're discarding precious image data; when you print, you'll see a loss of detail in the darks and lights.
The first step in fine-tuning a photo, then, is to drag the Exposure slider until the middle tones of the picture look acceptable to you (Figure 6-10). You can't add details that simply aren't there, but brightening a dark shadowy image, or deepening the contrast on a washed-out image, can coax out elements that were barely visible in the original photo.
If the dark and light areas aren't yet perfect, don't worry; you'll improve those areas next with the Levels control.
6.13. Adjusting the Levels
After you've spent some time working with the middle tones of your picture, you can turn your attention to the endpoints on the histogram, which represent the darkest and lightest areas of the photo.
If the mountains of your graph seem to cover all the territory from left to right, you already have a roughly even distribution of dark and light tones in your picture so you're probably in good shape. But if the graph comes up short on either the left (darks) or the right (lights) side of the histogram, you might want to make an adjustment.
Figure 6-10. Top: Here's a
landscape shot that will serve as the basis for all the Adjust-panel manipulations described in this chapter. The camera was in Program mode, with Auto White Balance turned on. Unfortunately, you can see by looking at the histogram that much of the tonal information is bunched in the middle of the graph. As a result, the photo looks a little "flat," without much contrast.