Improving your Photography with Histograms

A histogram in photography is a graph which represents the distribution of pixels in your image in a certain exposure range. It is a tool that helps you gauge your exposure, which, if used while photographing, can be helpful in making sure you return with usable images.

Take, for example, this image:

This is its corresponding histogram:

The histogram represents how much of an image is at a given brightness level along the graph.

From left to right represents total darkness up to total brightness. If a large amount of pixels are halfway bright, then there will be a large rise in the middle of the histogram, as is the case with this image.

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What's useful about a histogram is that it enables you to gauge exposure in various ways.

For example: if the image is underexposed, the histogram will be more biased to the left:

This histogram shows that the image's brightness is concentrated heavily to the darker, left side, and tops out only in the middle, at that. Here's what the image looks like:

If the histogram is biased to the right, you'll know that the image is overexposed.

This may be what it is you intend to achieve when photographing, which is fine. But in many cases it's better to take a good image with proper exposure and to edit it to look like you would like it to with more to work with, than it is to take an image that is unadjustable to begin with.

Histograms also don't necessarily need to represent exposure monochromatically. Many histograms show you the distribution of red, green, and blue brightness in the image.

If you know how to properly utilize it, you can correct white balance using a colored histogram. If you have a part of the area that you know should be white, and you can see where it is along the histogram, you can adjust the temperature and tint of the image until those areas in the histogram align like with the image above.

As useful as histograms are, I personally don't find them as useful as something like an rgb parade, which represents both exposure and color where you can see horizontally where a certain part of the image with a certain exposure is, or a vectorscope, which is very useful in addressing color casts and saturation levels.