Understanding the histogram

You don’t need to be a camera guru to understand the histogram on your digital camera. It only means that you need to learn more about your camera and its features. To get an optimum exposure, it is important to interpret your digital camera’s histogram to comprehend what it means and make the appropriate exposure adjustments.

What is the histogram?

Well, what is a digital camera histogram and what does it mean? This would be a great time to pull out your digital camera manual and learn how to display the histogram on your LCD display. On most digital cameras the histogram can be enabled so it displays every time you take a photo. To explain it briefly, it is a graph that shows the level of brightness of an image from the very darkest levels on the left (value 0) to the very brightest on the right (value 255), on the horizontal axis. Some histograms also display separate graphs for the level of brightness for the three primary colors- Red, Green and Blue (RGB). The graph’s height, vertical axis, is the measure of the density of image pixels of a particular tonal value. The taller the graph for a particular tonal value the more shades of that tone will display in the photo. A histogram also displays in many photo editing software programs including Adobe Photoshop, Lightroom, Aperture, among others.

Changing your exposure based on the histogram

Now that you have a better understanding of your digital camera’s histogram, we can move on to how you evaluate the exposure of a photograph. After you’ve taken a photo and you are viewing the graph on your LCD display, ideally you want to see most of the graph’s pixel density between the left and right brackets. If the pixels are bunched up on the left side of the graph it probably means the photograph is underexposed or will be too dark. On the other hand, pixels bunched up to the right side of the graph may mean your photo is blown out or overexposed, too bright. Any pixel detail information in these bunched up areas on the far left or right are probably lost or clipped. In an ideal situation, you want the pixels to just touch the left and right sides of the histogram. Now with this information you can go back and adjust your digital camera’s exposure so that the pixels are distributed across the graph which will result in a great shot.

Mastering your digital camera’s histogram can help you expose your subject properly and make sure you come back with great photos to share with your family and friends.