Grading the curve
October 14, 2007
Note: If you are new to histograms check out the background information in the previous tip, How to Read a Histogram.
A high-key image contains primarily light tones, and its histogram, which you can view either in some digital cameras' LCD monitors, or by opening the image on your computer in Adobe Photoshop or similar image-editing software, will be skewed to the right, with fewer darker-toned pixels. Here is a sample high-key image and its histogram:
This histogram is pushed against the right "wall" because there are significant areas of pure white in it, as well as significant areas of near-white and light tones. In this image it is an intentional artistic effect.
But in many images that are more realistic, this sort of histogram would indicate a loss of detail in the lightest areas, also known as blown-out highlights. In a more conventional image with detail retained in the highlights the histogram would taper to just touch the right edge at the bottom corner
The shape of the histogram will vary with each different image. There isn’t a right or wrong way it should look. It is simply a reflection of the tonalities in an image.
Diane Miller is a widely-exhibited freelance photographer who lives north of San Francisco, in the Wine Country, and specializes in fine-art nature photography. Her work, which can be found on her web site, www.DianeDMiller.com, has been published and exhibited throughout the Pacific Northwest. Many of her images are represented for stock by www.MonsoonImages.com.