Even if you don’t know what a histogram for photography is right now, the chances are that you have seen one either on your camera or even when editing your photos. Being able to read and understand your histogram is one of the best ways to improve your photos. So read on to get the basics of histograms and how to use them in your photography.
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What is a histogram?
Simply put, a histogram is a graphical representation of the tonal values of your image. It shows the number of tones of particular brightness found in your photograph ranging from black (0% brightness) to white (100% brightness). The data distribution on the graph will help you see how your exposure settings work in a graphical representation, making it easier to spot when you are on location before going into post-processing. The spread of these tonal value is known as “dynamic range”.
How to read a histogram
Many beginner photographers find this graph daunting. But don’t worry it actually pretty easy to read and understand. Dark tones are shown on the graph’s left-hand side with the tones getting lighter the further right you go (shadows or highlights).
The middle portion represents your mid-tones, which are neither dark nor bright. The vertical axis displays the number of tones of that particular lightness. Histograms tend to be exposure-dependent but can change with the tone curve and other settings in your editing software.
Clipping in a histogram
When part of your histogram is touching either edge, it’s known as “clipping”, which is a loss of detail in your image. Highlight clipping happens when the graph touches the right edge and indicates that areas are entirely white and devoid of detail. For example, when you are photographing into the sun you will probably find a particular area of your photograph (like the sky) that will be so bright, the highlights will be clipped.
Shadow clipping occurs on the opposite end when your chart is touching the histogram’s left side, which means there are areas that are completely black and have no detail. Both can be fixed by altering exposure settings either when taking the photo or in post-production. But in some extreme cases, this isn’t possible and so those clipped areas can’t be fixed.
To check if you have any clipping in your photos (either blacks or whites), you can access the histogram in your camera to view the graph. If you switch to “live view” mode and set your display to show the histogram you can see how the histogram changes in real-time as you move the camera.
If you see that your graph is being cut off on either side of the histogram then there is some clipping. So you can adjust your exposure settings to take another photo and check again.
You can adjust your settings or use exposure compensation using the “+/-” button on your camera. Dialling this positively will help make images brighter, whereas dialling this negatively will add more shadow details and higher contrast. You can use this to tweak your setting for the correct exposure to try to avoid clipping happening.
Many photographers would call “good” exposure when your histogram has most of your tones in the middle section of the graph. However, you can’t use the histogram as the sole judge of whether your shot is exposed correctly.
You can use the histogram as a guide to help you set your aperture, shutter speed and ISO settings, but it all depends on the type of photo you’re shooting. You might be a product photographer who is working with light-coloured products. In this case, your histogram will show a high amount of bright tones and some highlight clipping, which doesn’t mean it’s a bad shot. It just means that the photograph’s nature has a lot fewer shadows than a regular landscape shot.
Many factors go into exposing a shot, so it’s essential to take all of these into account. It can be easy to get drawn into whether your image is “good” or “bad” based solely on the distribution of your histogram graph.
All this will show you the graphical representation of the light distribution in your photo and help you discover any clipping where you might be losing detail in certain aspects of your image. You can use this graph to help you avoid loss of detail in your photos, but it can’t be used to determine the quality of any given shot.
Professionals may find glancing at the histogram after every shot worthwhile, but a lot of the detail can be brought back in post-processing if you’re shooting in RAW format.
Having said this, it will be a great habit to get into with your photography if you find you’re losing detail and contrast to get you shot correct at the time of shooting. Getting used to the graph and what it represents will ensure that your images are well exposed and the details you’re aiming to capture come across in the final photo.
Hopefully, you now understand more about histogram and exposure and can use this as a tool to help you in your photography.
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Kav Dadfar is a writer and travel photographer who has written over 400 articles on photography. He is also a judge on the Wanderlust Travel Photography of the Year competition and a speaker at camera clubs and events. He has years of experience shooting assignments with his images having been used by some of the biggest brands in the world.
This article on the histogram is subject to copyright. Words and photos by Kav Dadfar (That Wild Idea). Copying or reposting of photos or article elsewhere is strictly forbidden.