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Histo-huh? What’s a histogram? | Day 14

Histograms are one of the easiest things to read and one of the most intimidating things for new photographers.

A histogram is a bar graph representation of the range of luminance measured in black, gray, and white pixels in a photo.

Imagine that we converted your favorite photo into black and white. We all know that black and white photos are actually shades of gray in the middle, right? Well, if you could cut your photo into tiny pieces – a pixel each – and then make stacks of those pixels on a graph based on how dark or how light that pixel was, what you would have created is a histogram.

A histogram is simply a pixel count of the amount of dark, light and everything in between, presented in a visual graph.


In a real histogram, you wouldn’t see each pixel individually – this simplification allows you to imagine your photo like a puzzle with each piece in the right column with its matching shade of gray. Also – there are a lot more columns – 256 of them to be exact.

Pure black pixels are all zeros shown as 0 on the very left. Pure white has a numeric value of 255 and is shown at the very right. Everything in the middle has a numeric value ranging from 0 to 255, getting lighter as the number gets higher.

How do you read a histogram?

This is simple, I promise you! The higher the column, the more more pixels in that shade in are your photo. Let’s look at the following histograms:

reading a photo's histogram


Photos don’t need to be black and white to be shown on a histogram – even though it’s easier to learn that way. Histograms are like a map telling us how our images are exposed.

On the back of your camera you have a screen – probably ranging from 2 – 3 inches across. It’s not a very good way to eye your photo to know if you’ve properly exposed it. Tomorrow we’ll talk about using your histogram to help you judge if your image is properly exposed without relying on that tiny screen.

We’re almost at the half-way mark of our 31 Days. I can’t believe it!

Don’t forget these aweseome girls who are sharing this 31 Days journey with us:

31 Days of Grace :: Chatting at the Sky
31 Days to an Inspired Table :: My First Kitchen
31 Days to a Less Messy Nest :: Nesting Place
31 Days of Living Simply :: Remodeling This Life
31 Days of Autumn Bliss :: The Inspired Room
31 Days to More. . .With Less :: Beauty and Bedlam
31 Days to a Better Photo :: My 3 Boybarians
31 Days to Stress Free Entertaining :: Reluctant Entertainer


  1. just found you from ms a la mode. love your blog. am thinking of buying a name and moving from hsb to full wordpress. although we use it now (in hsb) i don’t like it.
    want a custom header again.
    From Raising Three Knights and a Princess

  2. Wow… half way through?
    I’ve been lurking here for a few days and picked up some great info!
    So glad I found you… though, I’m not exactly sure how I got here. Isn’t that terrible? I surf the webs so much I cannot remember?
    Looking forward to tomorrow…

  3. I always wondered what the purpose of the histogram was (C:

  4. The histogram is my #1 method of gauging my exposure now – I don’t know what I did without it. Especially shooting outside in direct sunlight, I misread my display photo a lot. Thinking it’s way dark when it’s really not. The histogram, saves me!

    I’m so happy you’re covering this. I feel like it’s something that makes shooting full Manual SO MUCH EASIER! I am teaching my husband to second shoot for me, in Manual and he’s got the histogram down pat already!

  5. i’ve had my camera for how long, and had no idea. I mean, not a clue….that that is what that is. Histogram! Word of the day. I like it.

  6. another one of those things I’ve never looked at in detail. I’d love to be a pro and shoot full manual and be happy with the results.

    Half way we are!

  7. I have really really loved this blog series! I’ve had my camera for 10 months now and knew a lot of the little stuff (I’ve read so many articles on aperture that it makes my eyes hurt now :P). But I have really learned A LOT in the last few days that I never even noticed or understood before. Thank you so much!

  8. I can’t wait to hear how to do this. I was just telling my husband how hard it is to tell if the exposure is right on the screen or not. Sometimes it looks great, then I upload it and it’s off.

  9. This is fabulous. I am currently taking a digital photography class for the first time and this week we talked about histograms. It didn’t really make sense to me, because it wasn’t really explained well. But I get it now! Thanks a bunch!

  10. Great tutorial, thanks for sharing it ! 🙂

  11. Great tutorial. Thanks for sharing it ! 🙂

  12. Thank you so much for the tutorial. I am a middle school art teacher. This puts the terms into language that my kids will understand while making it fun at the same time.