USM - what settings?

Got a fast easy question. What do you set the options to when using Unsharp Mask?

Do you change those options under different circumstances?

Rad

There are no fixed settings for Unsharp Mask that work well on all photos. The effect also greatly depends on the size in pixels of the photo).

When I prepare images for the web, I first resize them to about 720 x 480 pixels. Then I apply USM with the following settings: 100%, 0.3 pixels, threshold 6. If this sharpens the image too much (watch for halos around edges), I try 70%, or if it's not enough, 120% or even 150%.

When the image is larger (for example 3072 x 2048) the same settings have almost no visible effect. For such large images, I set the radius to about 1.0 pixels or so.

Just to prove that there's no fixed setting... For a web image I start at 130%, Radius 0.3, Threshold 0 and adjust from there. For full size, it's more like 180%, radius 1.8, threshold 2, and adjust for the image. Bit of a difference from Jesper's starting points.

I usually start with 75%, .5 and 0 and adjust from there - usually in the range of 50-100%, .5 - 1.5, 0-5. Sometimes I apply at the lower end of the ranges twice if there is no adverse effect - especially when printing (up to 8X10). But then again I am also learning as well and got these settings from someone else's recommendation - they are definitely not scientific but they seem to work pretty well.

My magic numbers have been 90, 2, 4.

As you can see different people have arrived at different numbers for their images.

Dont always trust what you see on the screen. You should be using a different USM for screen shots. You need to make some prints trying different numbers until you get whats pleasing. I did a bunch before finding the numbers that work well for my images.

-Pete

Does anyone know of a good tutorial that explains exactly how USM works and what it does. I have read the quick guide over at The Luminous Landscape, but I was after something a bit more detailed to help me understand why the settings I am using are acheiving what I see in my image. Thanks.

Rick