USM sharpening setting

threshold: when a pixel is determined to be regarded as an edge pixel and sharpened by a filter, it must be mostly different from the surrounding area. (The smaller the value, the stronger the sharpening)

The safe setting range is 3 ~ 21 (3 has the strongest sharpening effect and 21 is weak). If it is necessary to improve the sharpening intensity in practice, the threshold can be reduced to 1, but attention should be paid to observing whether the film is mottled.

quantity: determines the sharpening amount of the film. Its usual range is 51 ~ 151, but it is not absolute. When it is less than 51, the sharpening effect is not obvious. When it is greater than 151, noise and noise may appear (depending on the setting of radius and threshold).

radius: determines how many pixels the sharpening affects outward from the edge. In most cases, 1 pixel is used, but it can be increased to 2 pixels. Only 4 pixels are used in extreme cases.

medium sharpening: suitable for various products, indoor and outdoor and landscape films.

quantity 121, radius 1, threshold 3

Sharpen soft subjects:

For softer subjects (such as flowers, puppies, people, rainbows, etc.): quantity 151, radius 1, threshold 11

Sharpen portraits: Sharpen close-up portraits with this method, which will not make eyes appear too prominent and produce highlights in hair.

quantity 75, radius 2, threshold 3

Of course, it depends on the photos.