A Beginner’s Guide to Understanding Histograms

Do you know what a histograms is and how it can help you improve your photography? This guide will explain histograms and why they are important. Histograms are often overlooked, dismissed, or misunderstood but they are very helpful in many types of photography situations.

At a very high level, a histogram is a light meter for after you have taken a photo. It will give you a graphical representation of the light used to expose a photography. A histogram may look something like this:

Histograms can be viewed and many cameras as well as software applications on your computer.  In reality the histogram you find on your DSLR will have a lot more data on it.  Depending on the model of camera you may see things like aperture  ISO, and shutter speed used.  Also depending on the mode you may see only a single histogram, a histogram with the actual photo taken, or even several histograms broken down into different colors.  Here are some sample of actual on camera histograms.

From left to right the histogram will tell you about the dark, mid, and light content of your photo. From top to bottom it will tell you how many pixels in your photo are affected in that area.

In the example above there are more pixels that are dark than there are pixels that are light. Looking at this histogram and not the photo itself we would generally say the photo was underexposed.  Now look at photos taken at different exposures and their corresponding histograms.

There is no such thing as a good or bad histogram, but when looking at a histogram does it match the photo you were trying to take?  If you shooting outside with a bright sky your histogram will probably show more pixels on the right side, however a steep climb on the far right side suggests you overexposed the sky too much.

As a very general rule-of-thumb you want more pixels in the middle of your histogram. Remember though there are not good or bad histograms.  You may want to have a lot of bright or dark areas in your photo to get a specific look.   A histogram will not tell you if you have a good or bad photo, it simply displays the quantity of light vs dark pixels.