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Author Topic: How much USM, is enough? Is this Too Much  (Read 3724 times)
haidergill
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« on: July 18, 2007, 04:39:09 PM »
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Hi,

I trying to get to grips with USM in Photoshop. I usually process my photos in Capture One LE then sharpen etc... in PS. How much is right? The snapshot was first sharpened to amount 65 radius 10 threshold 2. Then for localised contrast enhancement (went with the default setting the Luminous Landscape tutorial) amount 10 radius 50 threshold 0. Is the photograph over sharpened? Is there a rule of tumb one can follow?



Oly E500 14-45mm 45mm f8.0 ISO200. IE tends too alter the brightness/colours.

Your help would be much appreciated.

Thanks
Haider
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Rob C
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« Reply #1 on: July 19, 2007, 02:07:36 PM »
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Hate to admit it in this sophisticated space, but I do 150;1;0 for everything and have never felt unhappy with it.

Ciao - Rob C
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richs
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« Reply #2 on: July 19, 2007, 02:39:21 PM »
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You might want to check out the this article by the late Bruce Fraser who probably knew more about sharpening than many.

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

If you want to get into it in great detail, he has also written a whole book on the subject,

Real World Image Sharpening with Adobe Photoshop CS2. It is quite technical, but leaves no stone unturned and is well worth the effort.

In answer to your question, I would say the example you show is slightly oversharpened - there is a halo around the neckline of his shirt.

Alas, having just purchased the above book, I am still learning myself and cannot offer an accurate remedy in this instance.

Regards,

Richard
« Last Edit: July 19, 2007, 02:40:22 PM by richs » Logged
haidergill
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« Reply #3 on: July 20, 2007, 08:49:16 AM »
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Thanks Rob & Richard appreciate it. I'll try to apply some of the stuff in Bruce Fraser's article.
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JeffKohn
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« Reply #4 on: July 20, 2007, 11:34:54 AM »
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In my opinion the picture is over-sharpened. There are obvious halos on high-contrast edges (shirt/neck, shirtsleeves, eye whites, etc), the specular highlights on the skin are exaggerated, and the hair also looks a bit crunchy in places.

You mention using radius=10, amount=65; that radius setting is far too high IMHO, and is the cause of the excessive halos. Try using a smaller radius and a larger amount. I probably wouldn't ever use anything above 1 or 1.5 unless I was doing local contrast enhamencement with a really large radius (like 40-50).

My workflow for D2x landscape images (or other images with fine details) has been to disable sharpening in the RAW convertor and then do my "capture" sharpening as one of the first steps in Photoshop. I sharpen the L channel in LAB mode, using a duplicate layer so I can mask if necessary. The parameters I typically use are radius=0.3, amount=350, and threshold=0. Sometimes I might bump the radius a tenth or so and drop the amount, it just depends on the image content. These settings are for clean images; if you have a noisy image these settings will exaggerate the noise so you'd probably need to increase the radius and threshold, while lowering the amount.

More recently I've been evaluating the new sharpening in ACR 4.1, so I've been using some weak sharpening in ACR (Amount=30, Radius=0.5, Detail=60-70). Then I still do the lab sharpening step described above, but I cut the amount in half to about 150.

For people pictures I usually use FocalBlade since it's pretty easy to get good results without over-sharpening the skin. But if I were to use straight USM I'd probably start with amount=150, radius=1-1.5, and threshold=2-4.

BTW I think it's worth pointing out that the optimal radius and amount settings are going to be dependent on image resolution. The parameters you use for a 10-12mp image are going to be very different from what you'd use for an 800x600 web JPG. For instance when I resize JPG's for the web I usually do so using Bicubic Smoother, and then apply USM with amount=70, radius=0.3 or 0.4, and threshold=0 or 1.
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JeffKohn
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« Reply #5 on: July 20, 2007, 11:42:06 AM »
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I like the "philosophy" of the Fraser/Photokit sharpening workflow. Although I rarely need to use "creative" sharpening (with good glass and technique, it's just doesn't seem to be necessary for most images in my experience), I do agree with having an initial capture sharpening step before other editing, and then a final output sharpening step after you've fully edited (and optionally resized) the image.

What I don't particularly like is the implementation of capture sharpening used in his book or in Photokit sharpener. It just doesn't seem to work very well, at least not with my D2x images. The problem, I think, is the use of an edge mask. To me, capture sharpening is not just about edge sharpening; it's more about detail sharpening. The AA filter and Bayer demosaicing process don't just soften edges, they affect all detail in the image. In fact I would argue that these steps have more impact on fine details in an image than they do on edges. So to me, using an edge mask for capture sharpening misses the point. Fine details benefit far more from the small radius, high amount approach in my experience, which is why I have my own actions for capture sharpening. I do like the creative and output sharpeners in Photokit, though.
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haidergill
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« Reply #6 on: July 23, 2007, 06:20:15 AM »
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I'll try your technique out Jeff and see what happens, thanks.

I figured out the halo/artifact around the neckline of the t-shirt is down to the lens. I'm using the 28-50mm (14-45) Zuiko kit lens. Apparently the dark band of the T-shirt with the almost white of the neck is pushing the lens beyond it's envelope. I'm planning on picking the 14-54mm pro version Zuiko when the price falls due to it being replaced by the SWD/USM enabled replacement.
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Hank
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« Reply #7 on: July 23, 2007, 11:53:36 AM »
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The "right" sharpening technique will also vary with the subject and the discipline.  While this might be nearly right for a wildlife portrait for example, it is WAY oversharpened for the human portrait market and tradition.  That's the part of the photo world where photogs often use difusing filters to soften images a bit.  Taking it one step further, we have the best response from our studio clients (i.e., best pay check) from images that are very selectively sharpened, often not sharpened at all- except for the eyes.  We sharpen the eyes on a separate layer, then use the opacity slider to adjust degree of sharpness, while typically not sharpening the remainder of a photo at all.
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haidergill
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« Reply #8 on: July 24, 2007, 07:07:02 AM »
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Thanks Jeff & Hank. I too agree soft look portraits look a lot more flattering, and convey a more warmer feeling. I usually develop in Capture One LE with 0 sharpening/NR then edit the resulting tiff in PS. I like the idea of selectively sharpening just the iris. Being a PS neophyte I take it I can go about using the method detailed below?

Make a new layer and merge the visible layers into it (Command-Option-Shift-E on Mac, Control-Alt-Shift-E on Windows), set the blend mode to luminosity, apply a somewhat stronger Unsharp Mask than is ultimately desired, with a radius setting that picks out the details you want to emphasize, then add a layer mask set to Hide All.

Use a low-opacity brush set to white, painting on the layer mask, to paint the effect into the areas that need it. When a layer mask is targeted for editing, the foreground and background colors are automatically set to black and white. You can easily toggle between painting with white to paint the effect in and painting with black to paint the effect out by pressing the x' key.


I'll try to make sure the resulting image still looks natural.
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Hank
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« Reply #9 on: July 24, 2007, 11:55:11 AM »
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You've got it.  Don't forget the opacity slider.  We use a little stronger USM than we would when doing global sharpening of an image, then use the slider to fine tune the effect on the layered image.  It's easier to make the adjustments and watch the changes than trying to get it "right" on the adjustment layer.
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