Spotlight on the Histogram: Reasons Why It Shouldn't Be Overlooked

Histogram

I've discovered that many of the most effective tools in photography are often overlooked; features that when used make life so much easier. This puzzled me at first, then I reasoned that it is probably due to the fact that some of the terminology in photography can be a bit daunting and therefore skipped over. For me, histograms fell under this umbrella of scary words. I was about to push it aside for a later date, but decided to challenge myself and dig my heels in. I'm so glad I did and you will too. Read on!

As with most things in photography, we can get into a really technical conversation about the histogram, in this tutorial I will share the basics, just what you need to get started. The histogram is a graph that shows the different colors present in your photo and their intensity. It looks sort of like a mountain range with peaks of different sizes.

Where the peaks fall on the graph will help you determine how bright or dark your photo is, making it a great tool to determine if your photo is over or underexposed. If the peaks are hugging the left side of the graph, this means your photo is underexposed; if it hugs to the right side of the graph, then your photo is overexposed. What happens when it is somewhat evenly distributed toward the middle of the graph? You got it! It means your shot is adequately exposed. Give yourself a sticker! I should tell you too that sometimes the graph reflects the predominant colors present in the scene (ex. if the scene has lots of dark colors or bright colors present) that's when you have to employ other techniques to help you make sure your photo is properly exposed. If you haven't already done so, refer to the articles: Exposure Exposed and Exposure Bracketing.

The image in this photo is underexposed.
Notice how the peaks hug the left side of the graph (bottom).
The colored coded histogram (top) shows a different histogram measuring the amount of the colors red green and blue in the photo.

This photo is overexposed.
Tall peaks are positioned to the right of the graph.

This is a more balanced exposure.
Note the distribution of peaks at the center of the graph.
The high peaks also relate to the dark and bright colors in the photo.

Refer to your camera's manual to determine how to select the histogram for your specific camera. The histogram can be used in a few different ways. Some cameras allow you to automatically view it immediately after shooting a photo. Others allow you to manually pull up the histogram after taking the shot. Choosing how to use the histogram is up to you. If you are shooting a scene that remains pretty constant in terms of lighting, you may chose to take a few photos first, use the histogram to determine if your exposure is what you want for the shot, then use those settings for the remainder of the session.

• When viewing a photo's histogram, always look for peaks bundled up at the far right and far left of the graph, they are warning signs of really under or overexposed shots. However, if you are purposefully underexposing or overexposing a shot for artistic effect then that's not a problem. 
• The histogram is particularly useful when lighting is tricky for example when bright highlights or deep shadows are present in your scene.
• If your camera displays the color-coded histogram look for peaks that are not in line with the others, it could mean that you have a problem with white balance in that photo.
• The bottom line is that the histogram is a valuable tool and should be put to use.
  
  

I hope you do just that. Have fun!