Unsharpen Mask is a pro tool that you can use now to sharpen your digital photos. Today, its name refers to a filter found in most image editing software. According to Wikipedia, Unsharpen Mask originally referred to a darkroom film processing technique using, “… a blurred, or “unsharp,” positive image to create a “mask” of the original image. The unsharpened mask is then combined with the negative image, creating the illusion that the resulting image has greater visual acuity than the original.” For our purposes, using the Unsharpen Mask filter in your image editor requires only a few clicks of a mouse button, moving three sliders, and doing so in proper proportions, will make nearly all your photos more intense, poignant, keen, razor edged, penetrating, biting, acute, or (as I am running out of words in my thesaurus) simply: sharp.
Where Is It?
Here are the filter’s location in two popular image editing software programs (Adobe Photoshop and Gimp):
Adobe Photoshop (Filter > Sharpen > Unsharpen Mask):
Gimp (Filters > Enhance > Unsharpen Mask):
How to use it
Once you have found the filter and opened it (Figures 2 and 4), you will see a window with three sliders: Amount, Radius, and Threshold. Rather than muddle through the verbage about how and why the three variables work both independently and in collusion with each other, let’s just focus on setting each of the variables and putting them work. I have found these settings, grouped by content, to be an excellent starting point (the settings are from Scott Kelly’s book, The Digital Photography Book, PeachPit Press, 2007. An excellent book that I keep in my camera bag for reference):
- For people: Amount 150%, Radius 1, Threshold 10
- For cityscapes, urban photography, or travel: Amount 65%, Radius 3, Threshold 2
- For general everyday use: Amount 85%, Radius 1, Threshold 4
Now, open a photo in your favorite image editor, and give these settings a try.
Which photos do you have that can benefit from this process? In my experience, the difference in a photo after using Unsharpen Mask, range from subtle to dramatic; however, the outcome is always an improvement over the original image. So, the answer to the question is “all of them”.