USM question

DJ-S1 · July 28, 2004

I've been reading a bit (instead of asking you guys 1000 questions

), and came across this explanation of USM technique:

The following options are available in the Unsharp Mask (Filter > Sharpen > Unsharp Mask):

Amount. This is the volume control of the USM. Increase Amount to increase contrast of adjacent pixels. Amounts ranging from 50 to 150 are typical, but this value can vary substantially depending on the amount of in-camera sharpening.

Radius. Specify the radius, from an edge, to sharpen. Use a radius equal to the resolution divided by 200. For a screen resolution of 96 ppi specify 0.5. If you're targeting an inkjet printer with a 300 ppi image, a radius of 1.5 is appropriate.

Threshold. Controls sharpening in smooth areas that lack contrast. Two adjacent pixels are eligible for sharpening if the difference in brightness is greater than the Threshold. Use zero for all pixels to participate, and a higher value to suppress sharpening in smooth areas. Use a Threshold of 1 to 5 to minimize noise. For close-up portraits use high thresholds to suppress sharpening of skin pores.

The degree of sharpening will depend on target resolution. Consequently, sharpening should be done at the end of your workflow.

My question is about the radius. In playing around with it, I have just been doing what I thought looked best on screen. :scratch Do you folks really select the radius based on the output device you are intending?

I have been sharpening last, though. And I have gotten some pretty nice results on scans of some old family photos, thanks to tricks I've learned here (layer masks rock, Andy! :thumb ) On deck I'm going to try out Neat Image...

pathfinder · July 28, 2004

DJ-S1 wrote:

I've been reading a bit (instead of asking you guys 1000 questions ), and came across this explanation of USM technique:

My question is about the radius. In playing around with it, I have just been doing what I thought looked best on screen. Do you folks really select the radius based on the output device you are intending?

I have been sharpening last, though. And I have gotten some pretty nice results on scans of some old family photos, thanks to tricks I've learned here (layer masks rock, Andy! ) On deck I'm going to try out Neat Image...

I usually do like you do and evaluate the image at high resolution 100% on the monitor.

But I believe it is true that the best sharpening mode is a function of the size of the image and the output device ie inkjet or linotype or whatever.

Some of the Sharpening plug-ins for PS do need an input as to output device as part of the information needed to perform the sharpening. I think this is particularly true for printers of large Art print type prints.

USM question

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