In the ocean of photography, there are few waters as muddy as the use of the unsharp mask. This filter, commonly found in Adobe editing software like Photoshop and Lightroom, but also used by a myriad of other programs, uses an algorithm of contrast enhancement to, typically, increase the perceived sharpness of an image. I won’t go into to much detail about how this is accomplished, but I will give some guidelines about its use.
- Unsharp mask does not add any actual detail to an image. In fact, it is somewhat destructive, particularly if overused.
- Unsharp mask should never be applied to an image being archived for your files.
- Unsharp mask should never be applied to an already sharp image, except…
- Unsharp mask is usually a necessary step when printing images, since most printers yield images with a slightly soft look, and…
- Some degree of unsharp mask can make photos for web look better on most monitors, most of which don’t display enough pixels per inch to make unsharpened images look good.
- Unsharp mask will sharpen everything, not just details. It is difficult to use unsharp mask on noisy images, since it sharpens the noise along with the details.
- With that said, it is possible to use a combination of noise reduction and unsharp mask together to create a usable image from a not sharp file. This combination sacrifices resolution to make an image appear sharper in print on the web.
- Occasionally I can rescue a not-very-sharp image with unsharp mask. Often this is the case in my work since I shoot news and sports and sometimes get images of great moments that aren’t quite sharp. It’s easy to take it too far, or to hopelessly pound a bunch of unsharp mask into a really soft image.
I use some kind of sharpening on all the images for my web site and social media. In addition to giving my work a little more “pop” than most of the images on the web, it helps overcome the image compression algorithms used by social media sites.
Finally, don’t let any know-it-alls on the internet (including me) tell you to “never” or “always” use the unsharp mask, or tell you your use of it was somehow wrong. It is a tool in the toolbox, for use as your creativity demands.