OP – The Blog

February 3rd, 2011

Digital Photography Basics: Reading Histograms

Posted By Michael Frye
Understanding how to read a histogram is the best way to judge exposure in high-contrast scenes like this

Understanding how to read a histogram is the best way to judge exposure in high-contrast scenes like this

With this post I’m introducing a new series on this blog. Every month or so I’ll be writing about photography basics like exposure, depth of field, camera settings, or the fundamentals of light and composition. I want to keep the content here relevant for all landscape photographers, not just advanced ones, and help everyone learn to make better, more expressive images.

So I’m starting with perhaps the most fundamental aspect of digital photography: reading histograms.

With film, exposure always involves some guesswork—you can never be sure you made the correct exposure until you develop the film. But with digital cameras you can tell immediately whether the right amount of light reached the sensor by looking at a histogram. This ability to instantly evaluate exposure is a game changer—the single biggest advantage of digital photography over film.

But many photographers are still guessing about exposure because they’re unable to decipher the histogram’s cryptic messages. Instead they judge exposure by how bright the image looks on their camera’s LCD screen. But while those little screens are extremely useful for many things, evaluating exposure isn’t one of them. There are too many variables: screen quality (usually bad), the LCD brightness setting in the camera, and the amount of ambient light.

A histogram is a much better way to judge exposure—if you know how to read it. If you haven’t figured out how to display a histogram on the back of your camera, you’ll have to spend some quality time with that fascinating book, your camera’s manual. Once you know how to view a histogram, what does it mean?

What Does It All Mean?

The most important parts of a histogram are the right and left edges. This histogram shows pixels pushed up against both edges, indicating overexposed highlights and underexposed shadows.

The most important parts of a histogram are the right and left edges. This histogram shows pixels pushed up against both edges, indicating overexposed highlights and underexposed shadows.

A histogram is a pixel map. It shows how dark and light pixels are distributed within your photograph—light pixels are on the right, dark pixels on the left. The shape of the histogram doesn’t matter. In other words, don’t worry if parts of the histogram shoot off the top, or whether there’s a spike somewhere in the middle. The only things that matter are the right and left edges.

If any pixels are pushed up against the right edge, that means parts of the image are overexposed—washed out. If any pixels are pushed up against the left edge, that means parts of the image are underexposed—black. Most cameras also have an overexposure warning—technically known as the “blinkies”—where overexposed parts of the photograph flash or blink. Some cameras also have an underexposure warning, which shows underexposed, black shadows.

Handling High-Contrast Scenes

In most scenes you should be able to get detail in both highlights and shadows. That is, the histogram shouldn’t touch either the right or left edge. But in some situations the contrast is too great for the camera’s sensor to handle, so it’s impossible to avoid either washed-out highlights (a spike at the right edge of the histogram) or black shadows (a spike at the left edge of the histogram), or both. In these cases, it’s usually better to retain detail in the highlights and sacrifice shadow detail. In looking at a histogram, it’s better to have pixels pushed up against the left edge than the right edge.

A properly-exposed medium-contrast scene, with nothing pushed up against either end of the histogram

A properly-exposed medium-contrast scene, with nothing pushed up against either end of the histogram

Histogram for a high-contrast scene with a spike at the right edge, indicating overexposed highlights

Histogram for a high-contrast scene with a spike at the right edge, indicating overexposed highlights

Histogram for a high-contrast scene with pixels pushed up against the left edge, indicating underexposed shadows, but properly exposed highlights. In most cases this is preferable—if you can’t get both, it’s better retain detail in the highlights and let the shadows go black

Histogram for a high-contrast scene with pixels pushed up against the left edge, indicating underexposed shadows, but properly exposed highlights. In most cases this is preferable—if you can’t get both, it’s better retain detail in the highlights and let the shadows go black



Why are highlights usually more important than shadows? First, our eyes are drawn to bright areas, so viewers immediately notice if they’re overexposed. Second, in real life we can always see detail in bright spots (except when looking at the sun itself, or the sun reflected in water or glass), but we can’t always see detail in shadows. It seems unnatural to find washed-out highlights in a photograph, yet it feels perfectly normal to see regions of pure black.

So if you can’t have both, 99 percent of the time you should sacrifice the shadows and keep the highlights. In most photographs, the lightest pixels should be close to the right edge of the histogram, but not touching it.

The Short Answer

This bears repeating: most of the time, the lightest pixels should be close to the right edge of the histogram, but not touching it. If there’s a large gap between the lightest pixels and the right edge of the histogram, the photograph is underexposed. If any pixels touch that right edge, the photograph is probably overexposed. For most photographs, all you have to do is make sure the lightest pixels don’t touch the right edge, but are near it.

Underexposed—the brightest pixels aren’t close to the right edge of the histogram:



Overexposed—a spike at the right edge of the histogram:



Proper Exposure—the brightest pixels near, but not touching, the right edge of the histogram:



The main exception, the instance when it’s okay to see a spike at the right edge of the histogram, is when the photograph includes the sun itself, or bright sky next to the sun. Because small areas around the sun are too bright to see in real life, it’s acceptable if such areas lack detail in photographs—it looks natural. The blinkies come in handy here: while the histogram tells you that something is overexposed, the blinkies show which parts of the image are washed out, and how large those areas are.

Adjusting the Exposure

So now that you can read a histogram, what do you do? If you take a photo, but the histogram doesn’t look right, how do you fix it? The short answer is that in automatic exposure modes like Program, Aperture Priority, or Shutter Priority, you need to use your exposure compensation dial to make the photograph lighter or darker. In Manual exposure mode you can change either the shutter speed or the aperture. I’ll explain exactly how to do this in the next installment of this Basics series.

Your Thoughts

I always welcome your comments and questions. Was this helpful? Do you always use histograms to check your exposure? Sometimes? Never? And if anything in this post isn’t perfectly clear, please let me know!

Naturally there’s more to the story. In some high-contrast situations I’ll bracket exposures so I can blend them together later in software, retaining detail in both highlights and shadows. And with colorful subjects, it’s important to look at the histograms for the individual color channels. The best way to learn about topics like this, improve your photography skills in general, and make more expressive and inspiring photographs is to take a photography workshop. There’s still space available in my Spring Yosemite Digital Camera Workshop in April. This course is a comprehensive, capture-to-print learning experience, with field sessions among the waterfalls and dogwoods of Yosemite Valley, and hands-on training with Lightroom and Photoshop. Find out more, or see all my upcoming workshops.

Michael Frye

In the Moment: Michael Frye's Landscape Photography Blog

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Please leave a comment

  1. michael mckee Says:

    Great article, Michael. It’s one of the clearer introductions to the subject I’ve seen. I do have to admit that I tend to push the exposure farther to the right than your examples show. Your first “properly exposed” example looks like it’s loosing a 1/2 stop of information to the right. Shooting raw and using Lightroom, I push the histogram to a small spike on the right. Raw files on newish DSLRs easily contain a 1/2 stop of exposure information in that spike, often more, depending on model. The third reason to include as much of the light end as possible is that the histogram is a logarithmic representation and the right hand side of it contains much, much more data than the left. A lost 1/2 stop on the right is over 1/4 of the total data in the image file. See

  2. michael mckee Says:

    See Luminous Landscape tutorials expose right for a more complete explanation.

  3. Michael Frye Says:

    Michael, thanks for chiming in.

    So this gets beyond the basics. You’re right that digital files contain more data in the highlights – the right side of the histogram. And yes, Raw files in newer DSLRs often contain more information in the highlights than shows up on the camera’s histogram. Part of the reason for that can be the contrast settings in the camera. Somewhere in the labyrinth of menus on every DSLR are settings for Sharpness, Contrast, Saturation, etc. Even though those settings only affect JPEGs, and not Raw files, the image you see on the camera’s LCD screen is a JPEG processed according to these settings – and the histogram is based on this preview.

    The default contrast settings on most cameras create JPEG previews that have more contrast than the Raw file, so if you’re using those default contrast settings in the camera, the Raw file will contain considerably more highlight and shadow detail than that JPEG preview or its corresponding histogram will show. For that reason I always recommend that people set the contrast lower in camera, even if they only shoot in Raw. It may take some experimentation to find the setting that most closely matches your Raw files.

    But after you’ve adjusted this contrast setting, I think you have to be careful about overexposing highlights. While I respect the guys at Luminous Landscape, I have to disagree with the idea of deliberately overexposing highlights in Raw images with the idea of bringing them back later in software.

    Don’t get me wrong – I’m a big fan of the Recovery tool in Lightroom and Camera Raw, and because of that tool, I don’t worry about small washed-out areas as much as I used to. But I’m talking about small areas. If they’re big enough to show up as a spike on the histogram, in my experience this can cause problems – it’s often difficult to get the tonalities I want in a file with substantial areas that are overexposed. Yes, I can technically bring back detail, but all the highlights in the image can appear flat and lacking in contrast. This may be a practical limitation related to the software controls available today, but it’s a limitation nevertheless.

    The problem is even worse if colorful highlights are pegged – up against that right edge in the histogram. The Recovery tool works well for small areas of overexposed white water, snow, etc., in Raw files, but its power is more limited with colorful subjects. If one of the color channels is clipped it can be impossible to avoid a blotchy look to those colored highlights. In fact I in my experience I don’t want a strong, saturated color to be even close to the right edge of the histogram. A darker exposure, with a bit of breathing room between the brightest part of the channel (often the red channel), and the right edge of the histogram, gives me better detail in those colorful highlights, and better control over the brighter colors in general.

    So I’d be careful about overexposing those highlights in Raw files, especially if you’ve already lowered the camera’s contrast setting.

  4. Mike Pfister Says:

    Thanks Michael, this is exactly what I’ve been looking for. I’ve played with every programmable feature on my Point and Shoot and was hoping to improve my photography. I’ve been hesitant to jump to the DSLR scene because I questioned whether I could improve on my skills without direction. Your thoughts on the histogram demonstrate an immediate possibility for improvement with my current equipment and provide the potential for me to take the DSLR step. Your knowledge of the subject and ability to teach it are much appreciated.

  5. Michael Frye Says:

    You’re welcome Mike, and thanks very much for chiming in with your thoughts. Glad this helped you consider taking the next step!

  6. Morgan Baugh Says:

    A really good explanation of the histogram. Your clear basic approach gave me a better understanding than all the others I have read. This gives me a fundamental understanding I can build on and I look forward to your future photography lessons. Thanks.

  7. Bob Dumon Says:

    Wow, for years I’ve occasionally, and only by accident, brought up the histogram setting on my Nikon D40. Of course I never had a CLUE what it was there for or how to use it. This brief tutorial is excellent, and I will certainly begin experimenting with histogram exposure fine tuning. Thank you so much for this terrific article!

  8. Michael Frye Says:

    Thanks Morgan – glad you found this clear and helpful!

    Bob, I’m glad to hear that this has given you a better understanding of the histogram, and I hope you’ll be able to put it to good use!

  9. Photo Critique Series: “Another Lousy Sunset” by Ken Hornbrook « In the Moment: Michael Frye's Landscape Photography Blog Says:

    […] Mainly this means making your exposures as light as possible without blowing out highlights (my recent post about reading histograms explains how to do […]

  10. Brett WIlson Says:

    Michael,

    Is there a pre-histogram capture in the newer dslr’s?.

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