AT A VERY fundamental level, a photograph is created of brightness tones from the darkest, black shadows at one end of the spectrum to brighter values and total white at the other end. This is commonly referred to as the tonal range. There are color considerations as well; in some images, color plays a prominent role—but the true foundation of any photograph is the tonal range. In some photo apps and desktop imaging programs, this is represented as a bar graph known as a histogram. A histogram’s shape often resembles a mountain, which is fitting: it reminds me of how the famous naturalist and mountain explorer ...

Get The Enthusiast's Guide to iPhone Photography now with the O’Reilly learning platform.

O’Reilly members experience books, live events, courses curated by job role, and more from O’Reilly and nearly 200 top publishers.