In photography, the dynamic range describes the difference between the lightest and darkest point within an image. It is given as the ratio of the darkest to the lightest point.
In an original (slide, negative, photo), the brightest point has a so-called minimum density and the darkest point has a maximum density. The difference between the maximum density and the minimum density is then the so-called density range, or dynamic range.
The dynamic range of the subject or the original is crucial for determining the correct exposure: Only if the exposure range of the sensor or film is greater than or equal to the dynamic range of the subject can all the details of the subject be captured. Otherwise, parts of the subject will be imaged in black and/or white.