Have you ever had a look at the histogram on your camera's LCD and wondered what it all means? It often seems like your camera is speaking a different language altogether. Luckily, you don't need a degree in computer science to figure it out. Here are some basic things you need to know to get the most out of your LCD histogram.
Most cameras these days have a histogram view. If your camera doesn't have it, all paint programs can show you a histogram either directly, or indirectly through the 'levels' menu.
How To Read A Histogram
The histogram is designed to give you a snapshot of all the different brightness levels in your photograph. It shows you graphically how many dark, medium and bright elements are in your shot.
For example, the histogram to the right is for the image on the left. There is a lot of dark in the photo (the underexposed singer) as well as some brighter areas outside. The number of dark pixels in the photo is reflected in the histogram with the high areas on the left (dark) side of the graph. There are fewer really bright areas (indicated by the lower peaks on the right side of the graph) and almost no mid-range brightness levels... the middle part of the graph has low peaks.
In contrast, the image above has a lot of bright areas, and that is reflected in the high peaks on the right of the histogram. There are very few very dark parts of the image (just the darker sections of branch on the lower right and top left) so the peak on the left of the graph isn't as large. You can also see a higher section to the mid-right of the histogram indicating more brighter colors. These will be the bright leaves.
Determine If Your Photo Is Too Bright Or Too Dark
Whenever you have too many of one tone, your photos will appear unbalanced. Overexposure occurs when you have too many whites in your photo (probably because you didn't use a fast enough shutter speed), and underexposure happens when you have too many dark tones in your image. The singer image at the top has some underexposed sections and you can see that in the histogram by the large peaks on the left (dark) side of the graph.
Here's something to do the next time you're out shooting. Instead of trying to figure out if you have overexposed or underexposed your photo by using your camera's LCD screen, try using the histogram instead. If the photo is overexposed, you'll see a huge bump on the far right of the histogram, and if it is underexposed, you'll see the same bump on the far left of the histogram.
Many photographers prefer this method because they know they can't see all of the detail when attempting to view their images on their LCD screens. This is especially the case when you are out shooting on a bright summer's afternoon. Once you learn how to read the histogram, you never go back. It's a much more handy reference point.
An Even And Balanced Histogram
The ideal histogram is even all around, meaning you have captured all of the little nuances and details in your photograph. When you are out taking pictures, keep this in mind. Remember that it's important to include shadows and bright spots, but if you have too many in your photograph, it will appear unbalanced.
If your histogram is heavily weighted to the right, it means you have too many bright spots in your photo. Like the sun photo above. You can reduce them by increasing the shutter speed on your camera. There's a similar rule when you have too many dark spots. You can decrease your shutter speed to increase the brightness and even out your histogram (and much more importantly, your image).
Update: Thanks to Glen in the comments below, I've added a balanced histogram example. Notice there are no 'very dark' and no 'very bright' colors and most of the peaks are in the middle section of the histogram. This means that all the detail in the photo has been captured by the camera. Don't worry that the left side has higher peaks than the right side. That's just because there is a lot of black in the photo (the black cheeta spots).
The next time you go out shooting, try to take one image with an ideal histogram. Every time you snap an image, look at the histogram, make some adjustments, and then try again. After just a few attempts, you should have something that's more even than what you started out with.
Most Histograms Are Uneven
As much as you strive to get a perfectly even histogram, realize that it's not easy. In fact, most scenes have uneven lighting by their very nature, and that's perfectly okay. There is a way to create a perfectly even histogram, and I recently wrote a few tutorials on it. The practice is called high dynamic range photography (HDR).
When you create an HDR photo, you basically take a bunch of pictures with different lighting levels and put them all together. Let's say you took a picture that's more weighted to the right of the histogram, and then you took a picture that's more weighted to the left. Wouldn't you agree that if you combined both, you'd have a more even histogram (and lighting too)? That's how HDR photography works.
Now, imagine you took 5 different photos at 5 different light levels (by increasing and decreasing the shutter speed for each photo). When you do this, your histogram is as even as it can possibly be. Every range of light tones gets covered. That's why the process of HDR photography needs at least 5 photos. You need this many to get an extremely balanced histogram.
So there you have it. There is no reason to fear the histogram. It's not written in Greek, and it's much easier to understand than your camera's LCD. Once you get the hang of it, you'll never look back!
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