Interpreting a Brightness Histogram on Your Canon EOS Rebel T6/1300D - dummies

Interpreting a Brightness Histogram on Your Canon EOS Rebel T6/1300D

By Julie Adair King

A brightness histogram on your Rebel T6/1300D is helpful for indicating tonal range. One of the most difficult problems to correct in a photo editing program is known as blown highlights or clipped highlights. Both terms mean that the brightest areas of the image are so overexposed that areas that should include a variety of light shades are instead totally white. For example, in a cloud image, pixels that should be light to very light gray are white, resulting in a loss of detail in those clouds.

In Shooting Information and Histogram display modes, areas that fall into this category blink in the image thumbnail. This warning is a helpful feature because simply viewing the image on the camera monitor isn’t always a reliable way to gauge exposure: The brightness of the monitor and the ambient light in which you view it affect the appearance of the image.

The Brightness histogram, found in both display modes, offers another analysis of image exposure. This graph indicates the distribution of shadows, highlights, and midtones (areas of medium brightness) in an image. Photographers use the term tonal range to describe this aspect of their pictures.

rebel-t6-1300d-brightness-histogram
The Brightness histogram indicates the tonal range of an image.

The horizontal axis of the graph represents the possible picture brightness values, from black (a value of 0) to white (a value of 255). And the vertical axis shows you how many pixels fall at a particular brightness value. A spike indicates a heavy concentration of pixels.

Keep in mind that there is no “perfect” histogram that you should try to duplicate. Instead, interpret the histogram with respect to the amount of shadows, highlights, and midtones that make up your subject. For example, the photographer was seeking to create a slightly dark, moody look in a candle image. And it was challenging not to blow out the details in the white gardenia bloom. So the Exposure Compensation value was set to EV –1.0, forcing the camera to deliver an exposure that was one stop darker than it normally would have produced.

So the histogram reflects that exposure. The fact that the white end of the scale didn’t show a heavy cluster of pixels was a good indication that the white flower details were not overexposed — something that’s often difficult to judge by simply looking at the image on the camera monitor.

Although there were a few “blinkies” in the candle flame (indicating fully white pixels), there were none in the gardenia, which was further help in deciding the right exposure settings.