Understanding the Histogram for Photography

The histogram for photography is often viewed with great confusion, but is actually quite a simple and useful feature.

A histogram is basically a graph that represents the spread of the pixels in a digital photograph. On the leftmost side we have the “dark” pixel count of our image and on the right side we have the “light” pixel count of our image. The vertical growth represents the amount of pixels representing a certain luminosity level as demonstrated below:

From here it’s easy to deduce some things. If the histogram has a vast majority of the graph volume towards the left, we have a darker image. Conversely, if the majority is clumped towards the right, we have a lighter, or more luminous, image. One of the most important things you can discern with a histogram is if you’ve “clipped” detail. This is something that is prevalent in the digital world. Unfortunately, digital photos don’t gracefully “clip” like film does, and having overexposed sections means you lose detail in an area and often get an ugly photo. You’ll notice these instances when parts of your histogram are pushed either all the way to the left or right, indicating those areas are either completely dark or completely white and showing no detail about the scene.

There is no one perfect histogram for all photographs. Remember that it is simply a tool to aid your compositions. You may often find yourself disregarding the histogram information on what is ‘technically’ correct in favor of what you feel is the proper exposure for your scene.