Using Histograms to Correct Your Digital Images
A histogram is a chart with 256 closely spaced vertical bars, usually forming a curve. In a histogram of your digital image, the left side of the curve represents the darkest tones in your image, the right side represents the lightest tones, and the middle hump represents the tones in between. You can use a histogram to correct your digital image:
1Make real-time corrections.
Some cameras have live histograms that you can view on the LCD and use to correct exposure manually while you shoot. You can make these corrections on only non-SLR cameras.
2Correct your image in-camera after you take the picture.
View the histogram on your camera’s LCD after you take the photo and make corrections by changing the aperture, shutter speed, or ISO until the histogram shows a more balanced curve.
3Use your image-editing software’s histogram to make corrections.
Most image-editing software includes a histogram to adjust the highlights and shadows of your image. In Photoshop, the Levels histogram features three Input Levels sliders that you can drag to adjust the histogram and change the image.