The Adjust Levels command is similar to the brightness and contrast, but gives much more control over tonal range. This is one of the most powerful tools and easy editing of photos.
"Adjustment level" shows a graphic image called a histogram. You can adjust the levels, be it drag the sliders or by entering a value in the box. Take a moment to experiment and soon get the hang of it.
Practical Tips:
expanding the image - Probably one of the most useful ways to use the adjust levels command. If you notice the histogram is compressed, you can manually drag the shadow and highlight sliders. This expands the image data and usually results in a more detailed, bright image. Note: in most cases, you will find yourself dragging the highlight bar to the left, and only slightly tweaking the midtone and shadow levels. Why? because more often than not, the image is underexposed, not overexposed.
auto-adjust levels - not as fun or powerful as doing it yourself, but there is an auto-adjust levels command.
