just noticeable difference (video codec) (JND)

Incolor representation, there are brightness and color nuances that are just perceptible. For this psychovisual evaluation, which is based on human perception and uses the smallest, just noticeable differences for evaluation, there is the evaluation parameter Just Noticeable Difference (JND).

JND is an evaluation variable for the quality of displays and for video codecs and is specified in a JND index.

JND, the smallest noticeable difference, indicates the number of gray levels depending on the luminance.

For displays, for example, the JND index is decisive for the number of distinguishable gray levels at a certain luminance of the display. It can be seen from this that the higher the luminance, the higher the number of gray levels.

For video codecs, a JND is defined as the probability with which a viewer can detect differences between the original video and the decompressed video with 75% certainty. Higher JND values approach 100% at 4 JND.