# Histogram > A graph of how many pixels in an image have each brightness value. Category: Lighting and optics. A histogram is a graph showing the distribution of brightness values in an image, from black on the left to white on the right. It reveals under- or overexposure and clipping at a glance. ## How PhotoRobot uses it The histogram in PhotoRobot Controls provides image statistics optimised for white backgrounds, so values remain readable even when the white background takes up most of the image. ## See on photorobot.com - [Image editing tools: histogram](https://www.photorobot.com/software/image-editing) ## Related terms - [Exposure](https://www.photorobot.com/glossary/exposure): The amount of light that reaches the sensor, set by aperture, shutter speed, ISO and light output. - [Highlight clipping](https://www.photorobot.com/glossary/highlight-clipping): Overexposed areas that are recorded as pure white and have lost all detail. - [White background](https://www.photorobot.com/glossary/white-background): A background of pure white (RGB 255, 255, 255), standard for e-commerce product images. ## Where this term appears on photorobot.com Mentioned on 1 page. Most relevant: - [Image Editing Tools](https://www.photorobot.com/software/image-editing): Histogram.