Over Sharpening?

Focus Pocus · September 1, 2005

Hi There,

Just wondering. . . I have seen several critiques of photo's where the image was said to be oversharpened. Can someone point out what the characteristics of an oversharpened photo are? Just curious.

Thanks!
Richard

Focus Pocus · September 2, 2005

Anyone?
Anyone?

davev · September 2, 2005

Hi Richard.

For me, the photo takes on a kind of plastic look, and a lot of times a white
halo will appear around the edges of the subjects in the photo.

Early on, I though that using unsharpen mask could fix a out of focus shot.
I was wrong. It will bring it back a bit, but if you start out with junk, you
end up with junk.

I over sharpened this photo. You can see the plastic look and the halo.

Focus Pocus · September 3, 2005

Thanks for the explanation Dave. Makes sense. I see the Halo in your picture.

Take care,
Richard

XO-Studios · September 3, 2005

Focus Pocus wrote:

Hi There,

Just wondering. . . I have seen several critiques of photo's where the image was said to be oversharpened. Can someone point out what the characteristics of an oversharpened photo are? Just curious.

Thanks!
Richard

Look at a pixel level around edges that go from a light to dark transition, you will see that there will be extra pixels, either light or dark, an excess of those are called halo's. They also happen around highlights. Also, you will see this in skin tones, around transitions and edges. The effect is very apparent on a 100% pixel level, but once you learn to recognize it (just like JPEG artifacts) they become very easy to see, even zoomed out. An easy test for yourself is to take one of your pictures, set the zoom level to 100% and run the unsharp mask at different settings, take a look, undo, and try a different setting. Also the forum Photoshop Shenanigans here on DGRIN has tons of good articles on sharpening.

rutt · September 4, 2005

In order to understand what "oversharpening" means, you first have to understand exactly what "sharpening" means, exactly what happens when you tell photoshop (or some other piece of software) to sharpen an image. I wrote a tutorial about this. If you don't know exactly what sharpening does, read this: http://www.dgrin.com/showthread.php?t=10408

OK, now that you understand that, I can telll you that there are three different ways you can oversharpen:

You can sharpen details you don't want to, including noise, by setting the threshold too low.
You can make the halos too big, obscuring details you want don't want to, by setting the radius too large.
You can make the halos too distinct, too bold and obvious, by setting the amount too high.

Notice that all three of these decisions are dependent on the particular image. If the image was shot at very low ISO you may want to set the threshold low and sharpen nearly all transitions. Images with noise will look terrible if you do that. If there is is a lot of fine detail, say hair, that you want to make look sharper, you need a fine radius. Images with fewer bolder lines will look better with larger radii. And the boldness of the halos that will work really depends on the contrast of the image.

Hope this helps.

Over Sharpening?

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