How To Read and Understand a Histogram

How To Read and Understand a Histogram (Professional Photographer Magazine Web Exclusives): "A histogram is nothing more than a bar graph. It shows how the luminance values in a digital or digitized photograph are distributed. The linear scale in a histogram runs from black at one end to white at the opposite end. With the exception of a scanned negative, the scale runs from left (black) to right (white). About 99 percent of the histograms we use in photography today have 256 increments, corresponding to 8-bit data depth. The histogram maps the distribution of the luminance values either as a composite of the red, green, and blue channels or in each channel, as you may have seen in the histogram display on some cameras and as option in Photoshop."