Sharpening in ACR 7.1

Regarding masking:

----------------------------

I know one person who sets default masking at 30, and another who sets it at 70. Optimal setting definitely depends on the image (I use non-zero masking values only occasionally).

I like the priniciple of masking, but not the reality: Unless masking gets 100% in areas of say sky, I think it does more harm than good: there is a dancing (call it: alternation) of unmasked and masked regions that I find more offensive than the noise itself. And in areas where edges meet smooth, sharpening extends just enough beyond the edges into the smooth to produce a twinkling around things that drives me crazy. Some people say they have no idea what I'm talking about, others say "Amen - brother".

Personally, if an image would need masking, I prefer a combination of desharpening (often at exactly -50: details available upon request) and/or now noise reduction in the regions where the noise is offensive, and/or enhanced sharpening in areas of interest (using locals, usually brush).

I'm not disagreeing with Jeff about masking - he's expressed his opinion and his taste - can't be disagreed with... Just saying: I really think each individual needs to discover for themselves how to sharpen things according to their taste.

More regarding detail:

-------------------------------

I know some people who always keep detail at zero, never ever above zero. Why? they find it's effect "distasteful". I know some people who often crank it way up. Why? - because they like it's effect. I tend to keep it on the low side usually - that's my taste: I usually like a little (ISO permitting), but not too much... - no right answer me-thinks...

And radius

---------------

To make a long story short, some people tend to prefer smaller ones, others bigger. But also it needs to be balanced with other settings: People who like large amounts and high detail settings, tend to use lower radius... I usually like a larger than average radius, but I often use smaller than average amount and detail.

Cheers,

Rob

I thank everyone for their various comments.  The one that indicated that Detail = zero was USM-like seems to be old news that Jeff's earlier comment negates.  He now contends that USM is not part of the ACR sharpening model.

It is because of the complexity of the interaction of the various sliders that knowing just what they are doing would be of immense help.  For the most part, each image needs its own sharpening, and just knowing a set of presets is of little use.  One needs to know what's happening under the hood so that one can properly understand what he/she is doing with each image.

I am also confused by the various statements I have read here and elsewhere about the use of the ACR sharpening for doing capture sharpening.  These statements seem to indicate one should achieve a good degree of sharpening, but not too much, particularly if one plans on doing further output sharpening later on, say, in PS.

Rather generally, capture sharpening should be used to counter the various elements of the capture (lens blur, diffusion, AA filtering, and demosaicing) that can cause the image to lose some of its inherent sharpness.  These effects are, in total, reasonably subtle, and thus so should be the capture sharpening -- indeed noticeable, but barely so.  But the various comments I am reading indicate using capture sharpening that is far from subtle, and, indeed, partway toward what one might consider output sharpening -- although not necessarily at output size/resolution.

The effects of capture error are also far less significant in larger areas of solid color, where none of the issues mentioned above comes into play in a meaningful manner.  This would suggest that a significant use of masking would be appropriate in applying capture sharpening.  But many things I read, and many suggested 'presets,' tend to downplay or even ignore masking.  Once again, these settings would appear to be more appropriate to output sharpening.

So it would be very nice if someone could provide meaningful information about what's really happening as you move the Detail slider from zero to 100.  I know very well what each slider is supposed to be doing (I can read the books as well as anyone -- and have), but none of us really knows what's actually going on with that Detail slider.

We know from Bruce Fraser what the general principles of sharpening are.  What we need now is someone like Bruce to write a treatise on how to enact those principles, such as they are possible, with the sharpening facility in ACR. We can attempt to infer what's happening by moving the sliders themselves, but it's really going to take someone with "inside knowledge" to do the job properly. So far we only have vague hand waving.

So, technical details to date:

Detail = 0 => "USM-like".

Detail = 100 => "Deconvolution-like".

Detail = 50 => in between...

Now, how to determine optimal settings, for you, and your photo?

In Rob's words:

* Amount - Magnitude of sharpening effect, as dictated by radius, and detail.

* Radius - How "tightly" the sharpening is "pulled in" around whatever is being considered an edge to be sharpened.

* Detail - Sharpening algorithm determiner. Algorithm at zero is biased to sharpen object edges, algorithm at 100 is biased to sharpen textural details. In between settings somehow blend or interpolate...

* Masking: Constructs a "layer mask" which modulates the opacity of the sharpening based on edge analysis... Alt-slider to see mask.

Note: The mask is not influenced by radius nor detail setting.

I have developed what I consider a *very* good feel for how to set these optimally for my taste, through *extensive* trial and error.

Note 2: How you set sharpener sliders is highly influenced by how you set luminance noise reduction sliders.

Rather than recant my own proclivities, I think I'll stop here, except for this:

If you use substantial luminance noise reduction, crank noise reduction detail slider up first to recover detail lost through luminance noise reduction (it can handle going all the way to 100 with no adverse effects), then consider uping the sharpening detail.

Legend: By "you", I mean "if the shoe fits...".

Ciao for now,

Rob

Thanks for all who replied, but, in all honesty, I am not the slightest bit interested in what other people do with their sharpening.  What I am trying to find out from Jeff (or some other knowledgable source) is just what the sharpening algorithms in ACR do.  I gather that Detail at 100 gives a deconvolution method akin to Smart Sharpening in PS.  That's good information.  At one time, I thought that Detail at zero gave something akin to USM.  But now Jeff says not.  But Jeff does not say just what sharpening technique is being applied when Detail is a zero.

Jeff, what's happening at Detail equal to zero?  and how does it (and in what sense) does it provide minimum halos?

many thanks,

grampus45

I think you are misreading what Martin wrote...

100 is deconvolution sharpening similar to Smart Sharpen in Photoshop. Zero is no devonvolution and max halo supression. Forget USM as it's no longer a model that is used in ACR/LR.