Understanding Camera Histograms for Better Photography

If you've just started with photography you may be content to leave your camera on auto and let it do the work for you. If, however, you are a bit more hands-on and long to tweak those manual settings, digital cameras have a tool that helps you perfect exposures time and time again.

Today we take a closer look at histograms for photography and how they can be helpful to photographers of all skill levels.

A camera histogram can be explained as a graph that plots the tonal values of your image. In other words, it details the portions of your image that can be found of the various levels of brightness, ranging from black to white, and how much each of these levels of tones is being captured.

At the left of your histogram are the black tones and at the right are white, with mid-tones being found in the middle. As with any graph, the Y-axis is for measurement. In this case, it tells you the amount of detail found at each tonality, so you can easily determine the dominant luminance in your image.

At the extreme left and right of the axis, you can find pure black and white, which are the areas of the image in which no detail is being captured; when you have large spikes at either end this is known as clipping. While in some instances clipping is ok, such as small bright areas of sky or areas that are heaped in shadow, you generally want to avoid clipping in your images if possible.

Why are histograms especially useful? They can help ensure that you capture a good exposure, that is an image that looks pleasing and is not under or over-exposed (too dark or too light). 

A histogram of a well-exposed image will reflect this with the majority of the data being evenly spaced in the middle of the graph. An under-exposed image will show most or all of the data bunched up to the left of the graph, while an overexposed image is the opposite with the data being bunched up to the right.

If this is your first experience with histograms it may take a while for you to understand them, so you are probably failing to see how they come in useful while shooting. After a while, however, a glance can provide plenty of information about an image, making it invaluable.

There are a few types of histograms you will experience in photography. Most modern digital cameras will provide you with a live histogram in-camera, which you can use to to view the information that your sensor is capturing in real time or have a quick check over a recently captured image, to see if your exposure is good or if you need to adjust your settings and re-shoot.

There are also histograms in Lightroom, Photoshop and other photo editing software, so this important info can be viewed post-capture during the photo editing stage. It is particularly handy when processing RAW files, as you can use it to make any necessary adjustments to your exposure while not affecting the integrity of your image.

By using a photo histogram tool while editing, you can simply move your exposure slider up or down as necessary, relying on actual data to make this decision rather than judging by eye; this means your image is being prepared to be viewed across all devices and printed successfully, without making decisions based solely how your image looks on your monitor, which can be an issue if your monitor isn’t properly calibrated.

Now that you know how histograms work, you can start to truly put your understanding of the exposure triangle to good use, to create spectacular photographs in camera. If you are ever stuck for inspiration or in need of photographic advice, stop by our photography blog.