High Key and Low Key are terms that relate to the way we illuminate the subjects with the lighting system in photography lighting techniques. How high key and low key relate to histogram concept?

An ideal histogram concept is relative, and a good photograph doesn’t mean it has the tone that is spread evenly. A bright intrinsic subject, for example, can produce the image where the histogram curve’s pattern tends to the right side which means very bright. This pattern demonstrates the high key photos.

On the other hand, the intrinsic dark subject will produce the image where the histogram curve’s pattern tends to the left side which means very dark. This demonstrates the low key photographs. See also night photography – the guidelines.

Low key lighting is a style of lighting that attempts to create a contrast tone between light and dark. And the subject is generally surrounded by predominantly dark grey to black tone.

The cat as shown in the figure is a simple example of low key photography. She is surrounded by grey to black background and a bounce light at the right side. Have a look at the histogram pattern that shows the curve pattern is brought to left side.

In a high-key portrait, the subject is generally surrounded by predominately light grey to white. High-key lighting is usually quite homogeneous and free from dark shadows. High key lighting is traditionally created by using three point lightings method that uses key light; fill light and back light as shown in the diagram below.

Key light shines directly upon the object and serves as its principal illuminator; for the strength, color and angle of the key determines the shot’s overall lighting design.

Fill light also shines on the object, but from a side angle relative to the key and is often placed at a lower position than the key light. It balances the key by illuminating shaded surfaces and lessening or eliminating the shadow cast by a person’s nose upon the rest of the face.

Backlight shines on the subject from behind, often (but not necessarily) to one side or the other. It gives the object a rim of light, serving to separate the object from the background and highlighting contours. See also how to trick the light.

The histogram for both types of high key and low key are not ideal since both are either brought together on the right side for high key photography, or the curve is brought to the left side for low key photography.

Histogram pattern here is like a diagnose tool to show how the tone is distributed on the photograph. Histogram doesn’t show you how the photographs should look like – it’s your job as photographer.

By Ki Grinsing

See also:

• How to trick the bright and the dark background
• Understanding photography flash – the guide number
• Photography exposure techniques
• Photography composition techniques