Threshold slider

joshhuntnm · April 23, 2008

I know one answer to this question is: it depends

But, here goes: what i your default setting for the threshold slider in the unsharp mask. I routinely sharpen at about 100%, 1 px, but don't really have a feel for what is normal on the Threshold slider. I am assuming the shot is pretty normal, in focus, you just want to crisp it up slightly.

DavidTO · April 23, 2008

I find this to be an odd question, taking one detail out of the whole sharpening question and asking about it out of context is pretty much useless, IMO. In fact, it's really unanswerable, without delving into sharpening theory. There are plenty of resources for that. Have you looked?

You'd be better off reading our sharpening tutorials, searching our forums for sharpening discussions and searching the wider internet for a basic primer on sharpening than you would be to isolate one small aspect of a rather complex issue.

pathfinder · April 23, 2008

Josh,

Sharpening is typically done at several stages these days - Capture Sharpenining in RAW to restore the sharpness lost due to digital capture, creative sharpening of selected portions of the image for artistic reasons, and output sharpening for sending to a printer. Each of these may be best served by different values and techniques.

The best explanation I have seen recently is the two videos by Michael Reichman and Jeff Schewe in the Luminous Landscape. Both are quite worthwwhile for improving the technical quality of your images.

Duffy Pratt · April 23, 2008

In general, the point of the threshold slider is to make it so that areas of the photo that do not meet the threshold do not get sharpened. I would normally use it to prevent artifacts from appearing in finely detailed areas. But on a typical shot, if I have set the other parameters up right, then I set the threshold to zero. That's an "it depends" with a brief explanation.

Duffy

joshhuntnm · April 23, 2008

DavidTO wrote:

I find this to be an odd question, taking one detail out of the whole sharpening question and asking about it out of context is pretty much useless, IMO. In fact, it's really unanswerable, without delving into sharpening theory. There are plenty of resources for that. Have you looked?

You'd be better off reading our sharpening tutorials, searching our forums for sharpening discussions and searching the wider internet for a basic primer on sharpening than you would be to isolate one small aspect of a rather complex issue.

I followed your advice. The rule of thumb I found was to start about 3. One other thing i didn't realize was that the lower the number the more the sharpening.

DavidTO · April 24, 2008

joshhuntnm wrote:

I followed your advice. The rule of thumb I found was to start about 3. One other thing i didn't realize was that the lower the number the more the sharpening.

arodney · April 24, 2008

One size fits all sharpening is a pipe dream:

http://www.creativepro.com/story/feature/20357.html

Icebear · April 25, 2008

joshhuntnm wrote:

One other thing i didn't realize was that the lower the number the more the sharpening.

I don't think this is a helpful way to think of the threshold slider. My understanding is that the lower the number the greater the number of "edges" that are sharpened. An edge being an area of contrast. What you are setting with that slider is the definition of an edge that the algorithm uses to determine where to apply sharpening. The higher the number, the more contrast is necessary before sharpening is applied to the "edge."

The "amount" always controls the degree of sharpening. That is: the amount of contrast applied.

Threshold slider

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