What is a histogram and why is it so important in photography?
If you regularly take photos whether with a DSLR, mirrorless camera, or even your smartphone you’ve probably heard of the histogram. Still, for many photographers it remains a somewhat abstract concept. In this blog, we clearly explain what a histogram is, how to use it while shooting, and how it helps when editing your photos. Whether you work with Canon or Nikon, the histogram is a valuable tool for better understanding and controlling the exposure of your images.

What is a histogram?

A histogram is a graph that shows how the brightness tones in your photo are distributed. It displays, for each tonal value (from black to white), how many pixels of that brightness level are present in your image. You can think of it as a kind of visual light meter that helps you judge whether your photo is properly exposed.

In most cameras (such as Canon or Nikon), you can enable the histogram via the Info button or through the display settings. In photo-editing software like Photoshop or Lightroom, the histogram is usually shown above your image or within the Levels module.

A digital photo typically works with an 8-bit colour channel, which means there are 256 possible brightness levels. These are shown on the x-axis, ranging from 0 (absolute black) to 255 (absolute white). The y-axis shows how many pixels fall into each of those brightness levels.

histogram
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Different Shapes of the Photo Histogram

A histogram can take many different shapes. There is no “perfect histogram,” as the shape depends entirely on the photo itself. However, there are a few recognizable patterns:

  • Evenly distributed: The graph forms a “peak” in the middle, indicating that the brightness is well balanced.
  • Shifted to the left: The photo contains many dark tones. This often occurs in night shots or dark interiors.
  • Shifted to the right: The image has predominantly bright areas, such as snowy landscapes or light backgrounds.

    More important than the shape itself is whether the data touches the edges: if the histogram reaches all the way to the left, you risk losing detail in the shadows (clipping). If it reaches the right edge, the highlights in your photo may be overexposed.

Why is the histogram useful?

On your camera’s LCD screen, a photo often appears brighter or darker than it actually is. This depends on ambient light, screen brightness, and viewing angle. The histogram, however, doesn’t lie: it objectively shows the distribution of light in your image. You can use it to check whether your photo is overexposed, underexposed, or properly balanced. This helps prevent important details from being lost in crushed shadows or blown-out highlights.

If you shoot in RAW, you can often recover details in extreme dark or bright areas during post-processing, but it’s better to get it right in-camera. The histogram is a useful guideline not an absolute rule and is especially helpful for high-contrast scenes, such as snowy landscapes, night shots, or portraits against a bright sky.

Using the Histogram While Shooting (Canon/Nikon)

Whether you use a Canon or Nikon camera, both brands allow you to view the histogram during or after taking a photo. Enable it in the settings or press Info while reviewing your image. Check that the graph doesn’t touch the edges—unless that’s your artistic intention. This way, you can immediately adjust your exposure on location, for example by changing the shutter speed or using exposure compensation.

Using the Histogram in Post-Processing

In programs like Photoshop or Lightroom, you can use the histogram to edit your photos more precisely. The sliders below the histogram give you control over:

  • Black point (left): deepens the dark areas.
  • White point (right): brightens the lightest areas.
  • Midtones (middle): adjusts the overall brightness.

The Pros and Cons of the Histogram

The histogram is an extremely useful tool, but it’s not a holy grail. The graph only provides information about brightness, not color or mood. Use it to support your evaluation of a photo, but also trust your eyes and your creative instincts.

That said, the histogram can be a very helpful companion, both on location and during post-processing. And it should be used as a supporting tool. If you want to know the exact correct exposure on location, a light meter is still your best option. And to properly evaluate and edit your image, make sure your monitor is calibrated.