The histogram is a bar graph that is built by measuring the tones in an image. A tone is a shade of a color. The vertical axis of the histogram represents how common a tone is. The horizontal axis represents the intensity (brightness) of a tone. The darkest tones are on the left, the lightest tones are on the right, and the remaining tones are in between.
You use the histogram to get a sense of what changes you can make to an image that will make it more pleasing without clipping. Clipping means some tones have become completely black or completely light. A small amount of clipping to increase the contrast of your image is common.
You can add multiple Histogram nodes to measure the changes of different nodes. This lets you guide your editing and makes it easier for you to experiment with new nodes.
The Histogram In Practice
- Because the histogram measures how often colors are used, multiple images can look completely different but have identical histograms.
- The shape of the peaks in a histogram are not very useful for photography. Instead, pay attention to where the peaks are relative to the horizontal axis.