Sharpening

[bigstick120]

How much do you sharpen you images? I have been using about 100-130% radius of .05-.1 threshold around 1 I think??

It seems like I could do more, do you sharpen until you see the halos around the image then go back a little?

Some say to sharpen a few times. Is there a general criteria to help you get there?

[hedstrom]

I think you're right. Sharpen until you see it's sharpened and then go back a little bit.

[alanhill]

Basically I agree.
Cameras and monitors are different, so are eyes and brains, consequently no two photographers will do exactly the same thing. Of course photos differ too, as you have realised.
The first rule is to keep your original camera files safely, preferably in a RAW format, so that you can rework them as often as you wish. The second rule is the one you have both already explained, experiment until you know you've gone too far, then back off (and if you see halos, you've gone quite a bit too far in my opinion). Always check the effect at 100% size, you can't really judge otherwise.

Alan

[JerseyJay]

Jeff,

For those that don't know, I'm assuming you are referring to Unsharp Mask tool available in Photoshop via Filter / Sharpen / Unsharp Mask. First of some terminology found on the internet:

Radius: controls how wide the edge rims become, and Radius = 1.0 is about the right ballpark, with 0.6 to 2.0 often being useful. Higher Radius values can cause halos at the edges, a detectable faint light rim around objects. Radius units are not the same as pixels, the units step in tenths, but the Radius width is usually at least 4 pixels overall, you will see various effects. Radius is a very important parameter, and the easiest way to ruin a good scan is with too much Radius. Inanimate objects can use the most radius, human faces can tolerate the least, and landscapes fall in between. But it really depends on the size of the details. Fine detail needs a smaller Radius, or else you may obliterate tiny detail of the same size as the Radius width. Large images have larger detail (more pixels involved) and can use more Radius, so therefore printing at higher resolution can support the larger radius. Radius and Amount interact, reducing one allows more of the other.

Threshold: specifies how far apart adjacent tonal values have to be (values of 0..255) before the filter does anything to the edges, before it is judged to be an edge at all. This lack of action is important to prevent smooth areas from becoming speckled. Low values should sharpen more because fewer areas are excluded. Higher threshold values exclude areas of lower contrast. Human faces want values greater than 1 or 2, like perhaps 5 or more. For inanimate objects, perhaps 0 or 1 is useful. General work, try 3 or 4. This control has little effect at high values, but has more effect changing between low values of 0 to 5. This Threshold is not to be confused with Line art Threshold.

Amount: is like a volume control, exaggerating the edge differences (how much darker and how much lighter the edge borders become). Amount interacts with Radius as to degree of sharpening, but it does not affect the width of the edge rims. Amount has a large effect, and values of 80 to 120 are normally usable if the Radius isn't too large.

Couple good articles on USM:
http://www.bythom.com/sharpening.htm
http://www.luminous-landscape.com/tutorials/understanding-series/understanding-usm.shtml

[bigstick120]

Thanks for the help, Ill keep reading and working at it