Acutance
![](/Images/godic/202501/07/Accutance.svg0242.png")
![Another illustration, where overshoot caused by using unsharp masking to sharpen the image (bottom half) increases acutance.](/Images/godic/202501/07/Usm-unsharp-mask0242.png")
![Unprocessed, slight unsharp masking, then strong unsharp masking.](/Images/godic/202501/07/Accutance_example0242.png")
![Low-pass filtering and resampling affect acutance.](/Images/godic/202501/07/Gibbs_phenomenon_100242.png")
In photography, the term "acutance" describes a subjective perception of sharpness that is related to 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.