Histogram

May 07, 2015  •  Leave a Comment

Tip of the week: Learn how to use the histogram to judge exposure while taking photos. Many cameras will have the option to change the brightness of the LCD screen. If you have the screen brightness set to low, all of your photos will appear too dark in bright light. Conversely; if the screen is set too bright in a dark environment, the photos will appear brighter than they actually are. The variations of environmental brightness and screen brightness can change your perception of the photos. For this reason, I strongly recommend using the histogram when judging exposure. The histogram is a graph that displays the tonal range of the image from pure black to pure white. On the graph you will see various undulations showing the amount of pixels for different tonalities in the image. Dark images will be weighted toward the left side of the graph (shadows), neutral images will be weighted in the center, and bright images will be weighted on the right side of the graph (highlights).

Many people like to have as much information as possible in their file. Because of this, many will study the histogram to insure that they are capturing the maximum tonal range in their photos. If the graph shows most of the pixels as being on the left side with none touching the far right side of the graph, that would indicate that the image is underexposed. If all of the pixels are on the right side with none touching the far left side of the graph, then that image is overexposed. If the graph has the majority of the pixels in the middle without touching the extreme ends of the left or right, that would indicate that the current exposure has full tonal detail from the darkest shadow to the brightest highlight in the photo.

This photo is a neutral exposure, however the screen brightness is set very low... The result is that the image appears underexposed on the camera.
Again, the same neutral exposure with a medium screen brightness. The image appears well exposed on the camera.
Neutral exposure with the screen brightness set too high. The photo appears overexposed on the camera now.
Neutral exposure with the histogram showing full tonal detail within the image. Notice how the graph is weighted towards the center on the histogram.
Overexposed image with the histogram. The histogram is now weighted towards the right side showing that the image is now too bright with detail lost in the highlights.
Underexposed image with the histogram. The histogram is now weighted towards the left side of the graph showing the the image is now underexposed.

 


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