Understanding and Using Your Camera’s Histogram

2 May 2022

If you've just started out 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 and how they can be helpful to photographers of all skill levels.

What exactly is a histogram?

A histogram is 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 is the black tones and at the right is 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.

Understanding and Using Your Camera’s HistogramUnderstanding and Using Your Camera’s Histogram

At the extreme left and right of the axis, you can find pure black and white, which is in fact the areas of the image in which no detail is being captured; when you have large spikes at either end this is referred to 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.

How is a histogram helpful?

Understanding and Using Your Camera’s HistogramUnderstanding and Using Your Camera’s Histogram

Histograms can be helpful in assuring 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 quick glance can provide plenty of information about an image, making them invaluable.

Live histograms vs histograms in editing

Most modern digital cameras will provide you with a histogram in-camera, which you turn on as you are shooting 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.

A histogram can also be displayed post-capture during the photo editing stage, on most popular photo editing software. It is particularly handy when processing RAW files, as you can use it to make any necessary adjustments to your exposure while keeping the integrity and overall quality of your image intact.

Understanding and Using Your Camera’s HistogramUnderstanding and Using Your Camera’s Histogram

By using a histogram 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.

Make sure your gear is calibrated

Put your knowledge to use

With this reading of histograms under your belt, 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.

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