How to use your Histogram
Updated: May 4, 2020
This weeks blog i'm going to take a look at the Histogram, What is it ? Why should you be using it ? When to use it ? And how it can improve your photography.
First of all don't be scared by the histogram, It really is your friend and can tell you a wealth of information about your photos and what is missing and how to improve them.
Yet it seems to be rarely used by a lot of people as it sounds and looks fairly complex, But in reality its far from that. I rely on it to give me feedback about the complete range of information in any image.
What is it ?
Ok so the basics of the Histogram are actually quite simple, It enables you to see exactly where the information in your file is.
You will generally have four Histograms on your camera, Luminosity (the value of light) The Red Chanel, The Green Chanel and the Blue Chanel or RGB as you will hear them more commonly referred too.
Most digital cameras will actually have the ability to show all of these on one Histogram so the information is visible for easy reading much like the above image.
The far left of the Histogram represents true black and slightly further in, the shadow information, The far right shows the true white information and slightly further left the highlights, everything in-between is your mid tones.
It can give you all the details you will need to tell you if your exposure is indeed correct and what you're looking for. But wait, why not just look at the image on the review right ? Well the human eye is good, but it's not that good that it can give you as much feedback as the Histogram. You can tell so much more and it will help you when you come to process the information you have.
For example the graph below will show you a few scenarios of an image that has been either over or under exposed or the holy grail, correctly.
If we look at the over exposed Histogram you will see it is all the way over too the right and hardly any information in the left.
This means that your whites have "clipped" meaning they have gone past true white and have blown out, Thus there is going to be a big ugly white patch somewhere in your image. The under exposed Histogram shows that you have no highlight detail in your image and some serious clipping on the blacks, so typically some very large completely black areas with no information in.
The normal image shows that you have a good deal of information in your mid tone section, and your white/highlights & your black/shadow information is good, You haven't clipped them and your image should have a large amount of information available to you.
Now each scene will dictate how the histogram behaves, if you are shooting into direct sunlight you will have very contrasty image, depending on how you expose it of course.
The camera will see areas of heavy bright luminosity and therefore will try to under expose to allow for it, So you might get the sunlight exactly how you want it but you will be left with heavy clipping of the shadows as it under exposes everything else. Of course camera metering has come on in leaps and bounds over the years but it still can't get it bang on every time. The Histogram will be your equaliser and tell you if you need to up the exposure or lower it.