Oct 14, 2011


 Welcome to the world of histogramia.
Here I will teach you what a histogram is, and how it helps you take better photos.
 Try not to get confused.*

What's a histogram?

It looks like this:

 To quote Wikipedia:
An image histogram is a type of histogram that acts as a graphical representation of the tonal distribution in a digital image. It plots the number of pixels for each tonal value. By looking at the histogram for a specific image a viewer will be able to judge the entire tonal distribution at a glance.
Blah, blah, blah. ;)
In English, an image histogram is a graph that shows you all the different shades in an image from pure white to all black. So histograms differ depending on the photo.

(p.s.: Usually you can find a setting in your camera's menu that says "histogram." Just turn that setting on to see a histogram when shooting! Refer to your manual if you need help...) 
Okay, now you know what a histogram is. 
But how does it work? 

Take a look at this photo:
(yep, same one I posted yesterday :) )

See that there is quite a range of tones in this photo, from the almost white sun, to the dark shadows in the bottom half of the photo.
In a histogram the edges are the most important part.

Okay. The left side of this histogram represents the darker places in the photo. And the right side represents the light spots.

Keeping that in mind, look at the far left side of the histogram. See that grey strip running up the side? That represents the dark places in the photo, which are also the blue shaded places in the below photo.

There the histogram is showing you those places are completely black. You can't "retrieve" them, or lighten them up, even in a good editing program because the camera just captured pure black. 

This is what would happen if you tried to lighten those places up:

If you look closely, you can see areas that are just plain black. They aren't retrievable...you can't lighten them to see more detail.

And same with the white parts of the photo:

The white parts of the photo are shaded red... it's just the sun in this photo. But I can't darken the photo to be able to see the round shape of the sun, or see more shadows.
It can't darken the part that is completely white, because the camera didn't capture any detail there but plain white!

On the right side of the histogram you can see a little grey going up the side of the histogram. That represents the white part, the sun in the above photo.

Now, in the sunrise photo, (the good one, the first photo I posted) it was okay for me to have "irretrievable" places that were completely light or completely dark. I liked the photo that way... I didn't need to lighten or darken those places.

But in a photo like this...

Poor flower :(
it's NOT good! 
You don't want a lovely orange flower overexposed to the point of being white. You won't be able to fix it, even in a fancy editing program.
 When I try to darken it this is what happens:

Poor, poor flower :'(
Now, not all photos are as drastic as this. There may be a time when you are taking photos, and they look fine on your camera, but then you look at them on the computer, and you realize that there were places that were way too dark or too light. That is when the histogram comes in handy. You can read it and see quickly if places are too dark or light

(for the 1st flower photo)
As I quoted before, the edges are the most important part. If you have strips (aka pixels) running up the left side, you know some places are irretrievably dark, and if you have pixels running up right side, you know some places are irretrievably light. 

So watch your histograms, friends! 

*if you read this whole thing without getting confused, brownie points to you!


  1. excellent. this could be a huge help 'in the field' - making sure you have a photo you can work with once you get back to your computer. well-explained, Elise.

  2. Anonymous10/27/2011

    Good explanation ... i had never truly understood histograms ... thanks! -Dad