Unsharp Mask??

[JohnQ]

I have a question, why the heck do they call unsharp mask, unsharp mask? I think I can better understand how it works if I understand why it is called what it is. Can anyone help me with this?

[studio206]

it's called an unsharp mask because that's what it does, it mask, or hides, a soft focus or unsharp image. all it really does is increase the contrast and it does sharpen a little bit. it's great for getting rid of UV haze if you 4get your UV filter be4 shooting. unsharp mask are commonly used in scanner software... it's usually on as a default so unless you are playing around with settings you will never notice it's there. it's a useful tool but not extremely effective. i found that you get the best results when you have your settings at:

Amount: 20%
Radius: between 30 to 60 pixels
Threshold: 4 levels

[Ronald S. Jr.]

I'm a 150,.3, 0 kinda guy myself. I also often use 15,150,0 to bump up contrast nicely, if need be. Just test it out...different amounts can yield very different results.

[patrific]

The history of the Unsharp Mask (from the darkroom days) was a duplicate of the negative was burnt through some glass as a contact exposure, to make a reversal (or positive negative of the original.) The duplicate was a bit soft or "unsharp" and this was used to burn to the print as a first burn before the negative was used to expose the print. It was a royal pain but it usually helped a soft picture look crisper. The mildy blurry positive caused a small delineation between light and dark, which is what the digital USM does.

[patrific]

I like to visualize things beyond the math. Photoshop can be a big math test to most of us at times but there are ways to show you pretty much how the chemistry in the darkroom moved towards the math in Photoshop.

An alternative I use fairly often to the USM in Photoshop is using the "High Pass" filter. I tell quite a few people to do this for simplicity and effectiveness.

I always have my layers pallet open -- so please open yours if it isn't open. Drag your background layer down to the "new layer" icon at the bottom of your layer pallet. It is next to garbage can. You now have a duplicate of your background.

Make sure your background copy is selected. Go to the "Filter" menu and go to "Other" and then pick the "High Pass" filter. It opens and you see it only has one slider (radius) and I like that! Now for a print @300 dpi I pick a radius between 2 and 3. For web @ 72 to 95 dpi 1.5 or less. I print all of my work so I usually just keep it on 3 for 99% of the time. Click "OK."

You now see that you have a grey image with black and white outlines. This is the mask now and your radius is what you selected in the High Pass to make that mask.

Now to make it all work make sure you still have the background copy selected. Go to the top of the layers pallet to the "blending mode." Change this from "normal" to "overlay." This works very much like the darkroom and shows a visual of what the USM in PS does. If it seems too strong -- lower the opacity. Not strong enough? Change the blending mode to "hard light" or play and use any of the blending modes in the overlay section. Play as you wish. Be careful not to make it cartoonish or too strong unless you are trying to make an effect like that.

[akhater]

patrific I agree with you, I use high pass sharpening myself mainely because it can be undone. here is a tutorial on it with some pics
http://www.adidap.com/2006/10/27/photoshop-tutorial-none-destructive-high-pass-sharpening/

[patrific]

akhater -- the more things you can undo or modify the better. I remember the old PS's where you had an undo and that was it. It really made you think (or curse) what you did two procedures ago. I will check out the link -- thanks.

[patrific]

patrific I agree with you, I use high pass sharpening myself mainely because it can be undone. here is a tutorial on it with some pics
http://www.adidap.com/2006/10/27/photoshop-tutorial-none-destructive-high-pass-sharpening/


Very nice link -- I like it. I learned to go to a more subtle mode using a larger radius. Cool.