Histogram, Histogram, what art thou, O histogram

Read the Histogram

Because this image was overexposed, its tones are clustered on the right side of the histogram.

The key to correcting an image’s tone problems lies in understanding the histogram that appears at the top of the Adjust palette. The histogram is a bar chart that shows the distribution of tones in an image. Black is on the far left edge, white is on the right, and everything else is in between.

By learning to interpret what the histogram is telling you, you can take much of the guesswork out of correcting bad photos and discover ways to make good photos even better. Usually, you want photos with as broad a range of tones as you can get. Think about boxes of crayons: you can create a much more detailed image with 64 different crayons than you can with just eight. Likewise, if the bars in the histogram are crammed together in a narrow space, your image probably doesn’t have the resources it needs to depict subtle detail.

With a well-exposed image, the histogram’s bars will stretch across the full range of the graph. If your histogram’s bars are clumped on either the left or the right side, the image is probably underexposed (lacking good highlights) or overexposed (lacking good shadows), respectively. If the bars don’t stretch to either edge, then your image lacks contrast.

Reprinted by permssion of Ben Long:

www.completedigitalphotography.com.