What are Levels and Histograms and How can They Help?
The “Levels” function is a tool used by digital editing software to manipulate the tonal values or brightness levels of an image. The standard 8-bit digital image contains 256 colours which are mapped as discrete black, grey, or white tones on a histogram, with 0 = black, 255 = white, and 254 shades of grey in between. When you take a photograph, the pixels of an image are sorted into one of these 256 tonal values, and stacked to make a vertical bar. When the bars are lined up together in numerical order of tonal value on a graph with 0 (black) on the far left, and 255 (white) on the far right, they create a curve on the graph. This curve (or curves in some cases), is the image’s histogram. Some digital cameras have a function that allows you to view an image’s histogram directly on the camera screen. Even if your camera doesn’t have this function, a program such as Adobe Photoshop will be able to produce your image’s histogram in the Levels function. By examining the shape and placeme
