Why it’s Important to Know About Histograms
Camera LCD displays are pretty bad at accurately representing what the photo looks like. This is why you should be using Histograms.
Histograms give you a mathematical representation of how well exposed a photo is, which helps you to get the best photo possible when out on a shoot.
What is it and what does it tell you?
The histogram shows you a scientific review of an exposure after you’ve taken it. It essentially tells you how evenly exposed a photo is.
LCD screens aren’t very good at conveying this information because their effects are largely based on the ambient lighting conditions you’re in and the brightness of the screen itself.
You’ll find an option to view the histogram in all cameras. Some compacts that don’t rely on the viewfinder to compose a photo will also show you the histogram in real-time.
How do I read the histogram?
A histogram is mapped out by brightness on a grayscale: black is on the left, white is on the right and all the different shades of gray are in between.
In a standard jpg image, there are 256 different recorded values of brightness: 0 is pure black and 255 is pure white. These 256 values are mapped out in a histogram and each pixel from the image is assigned to a value.
Now, let’s have a look at what that looks like:
The image above has been correctly exposed and the majority of it’s pixels are away from the black and white values in the histogram; what may appear to be black in the photo is actually just a very dark shade of grey.
If you were taking a photo at night, your results may be very different but you always want to stay away from the pure black or pure white values.
Having pixels in these extreme values means that your photo has been either over-or under-exposed. It will therefore need to be retaken as is detail missing that can’t be recovered in photoshop as the shades of color have been lost; it’s pure black/white.
Have a look below at an overexposed image and an underexposed image with their respective histograms.
It’s also possible to see your histograms in the three channels of color: red, green and blue (also known as RGB).
For the correctly exposed image, it looks like this:
Using this version of the histogram is most important when shooting brightly colored objects as it’s possible to blow out (overexpose to the extent that information is lost) the corresponding channel of color without it appearing in the main histogram.
Now that you understand how histograms work, you’ll start to find yourself using them more and more when taking photos. They’re a great way of making sure that you’re getting it right in the camera and decrease your reliance on computers to finish off your photos.
Your Free Quick-Start Photography Cheatsheet
In order to simplify the process of learning photography, I’ve created a free download called The Quick Start Photography Cheatsheet and you can download it below.
Here’s what you’ll get:
- A downloadable cheatsheet to carry with you as you shoot
- Detailed summaries of each section of this post
- External links to relevant articles and blog posts
- At-A-Glace Images that will explain how each exposure works
- And much, much more…
This downloadable cheatsheet gives you detailed summaries of every section of this post, as well as links to relevant articles, and at-a-glace images that will explain how exposure works.
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