Digital Imaging Reset

Acutance

Acutance: A physical rather than subjective measure of the sharpness of a photographic image.

“In photography, acutance is the edge contrast of an image. Acutance is related to the amplitude of the derivative of brightness with respect to space. Due to the nature of the human visual system, an image with higher acutance appears sharper even though an increase in acutance does not increase real resolution.” – Wikipedia

A physical rather than subjective measure of the sharpness of a photographic image
Unsharp mask (USM) applied to lower part of image. Radius:50, Amount:3, Threshold:0. Areas neighbor to dark colors are lightened, areas neighbor to light colors are darkened. PNG Save is lossless. Any artefacts seen are due to USM itself.