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DPChallenge Forums >> Tips, Tricks, and Q&A >> Sharpen Vs. Unsharp mask
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11/06/2003 11:30:06 AM · #1
What is the difference between the "sharpen" function and "Unsharp mask" in image editors. I mainly just use the shaprening tool since I dont understand what unsharp mask does...

Thanks

James
11/06/2003 11:50:49 AM · #2
control.

Sharpen you have none, unsharp mask you have unlimited flexibility.

But like always, with more control, means more room to screw it up.

'with great power comes great responsibility' to avoid spiderman references
11/06/2003 11:57:12 AM · #3
what Gordon said..
One of the main things I've learned about doing the USM, is find an edge or a couple and watch them as you change the levels.

You will see halo's if it is going to far. While this may add a desired effect it may also lead to comments of "it looks oversharpened, etc.)
//www.dpchallenge.com/tutorial.php?TUTORIAL_ID=4

is very helpful also.

11/06/2003 01:10:00 PM · #4
thanks, I have played with unsharp mask, but I just dont have the hang of it yet. the radius, amount and threshold values have me all confused. I will do some more reading and experimenting tonight.

James
11/06/2003 08:52:03 PM · #5
I only use USM. Whenever I use sharpen it seems to leave a pattern of weird squares all over the image...
11/06/2003 09:36:42 PM · #6
I always use USM on files I want to print. Strangely enough, I almost always end up using Sharpen for my DPC entries. Seems to do the sharpening just the way I want it. This doesn't seem to be true for larger files. Very odd. But for more control USM is the way to go.
11/06/2003 09:51:33 PM · #7
I used to use "sharpen" all the time until I saw people scoffing at it here. I forced myself to learn how to use USM, and have been using it exclusively ever since. I wish I could find the one tutorial that helped me the most (other than the one linked prior to this post). If I come upon it, I'll be sure to post it.

I found one that was simple enough that my lone functioning brain cell was able to absorb it! :)
11/06/2003 10:07:24 PM · #8
Originally posted by jab119:

thanks, I have played with unsharp mask, but I just dont have the hang of it yet. the radius, amount and threshold values have me all confused. I will do some more reading and experimenting tonight.

James


My 60-second overview of the USM settings:

Amount:
controls how much sharpening is applied. Not much else to be said here.

Radius:
Technically, the term applies to the matrix used to generate the effect, you can think of it in terms of the original's blurriness. The blurrier the original, the larger the radius may need to be. Start with 1.0 and adjust.

Threshold:
Determines the minimum difference in luminance between pixels that triggers sharpening. Raise this above zero to avoid increasing noise while shaprening. A good starting point is a value of 3-5.

11/06/2003 11:47:53 PM · #9
I think radius or diameter is the distance from the junction it extends the sharpening effect.

I have some examples of photos with different amounts of USM applied to illustrate the effect posted in this pBase gallery.

My starting values:
Amount 66-88%
Diameter 0.6-0.8
Threshold 5-7

I often apply lower settings twice. For higher-resolution (print) files the diameter value will probably need to be raised. For detailed/complex images, lower the threshold to enhance detail. For images with smooth gradients (e.g. portraiture) use a higher threshold setting to avoid unwanted banding.

Message edited by author 2003-11-06 23:51:15.
11/06/2003 11:51:24 PM · #10
I have noticed though, sometimes when you use the sharpen, the photo tends to have more noise depending on the pixelation capabilities of your camera. I think it should be used sparingly unless you have a higher pixel camera, or maybe try taking the shot over.
11/07/2003 12:46:19 AM · #11
While at a workshop put on by Adobe, the speaker recomended these settings and I have been using them since with good results on anything from night shots to full light shots.

Amount: 150
Radius: 0.5
Threshold: 4

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