A couple of years ago I wrote a broad explanation of Unsharp Mask, and recently I discussed my method for sharpening for web. Many people have told me they found these useful, but I'm often implored for a tutorial about print sharpening.
I'm sorry to say it can't be done. Not properly. It's impossible to write a list of sharpening steps or settings that will work for everyone. There are just too many variables - your camera, your subject, your shot settings, your crop, your monitor, your chosen print size, your lab, your chosen media, and ultimately, your taste.
So if people ask for advice about print sharpening, I invariably tell them "do your own testing". And that's what I want to talk about here.
I did some test prints with various sharpening settings, and I'd like to share them with you. Before I start, let's make something really clear: MY RESULTS WILL NOT BE YOUR RESULTS. The settings I used for these photos, at my lab, have about as much relevance to you as the brand of breakfast cereal I ate this morning. Ultimately, you'll have to find your own settings. But I hope I can give you some broad guidance about the process.
I chose two photos - one with good (though not spectacular) focus, the other with poor focus. Both were shot in raw format on a 6.3MP camera, and had basic raw processing performed on them in ACR - nothing fancy.
From those two photos, I prepared three sets of test prints (the poorly-focused one I just printed at 6x4"; the well-focused one I printed at both 6x4" and 12x18"). Within each set, I played with a series of sharpening settings, as I'll discuss.
PHOTO 1, SET 1
The first photo (acceptable focus) was a head-to-hips shot composed like this (in a foolish oversight, I chose photos which I hadn't sought permission to display, so I hope this illustration is sufficient to show composition):
So, I started with some tests at 6x4 size. In each case, I'll show you a 100% crop on the eyes of the file I sent to the lab.
1.1.A: No resizing, no sharpening, nothing. Just sent to the lab as is:
1.1.B: No resizing. Sharpened with USM (Unsharp Mask) settings 300/1/5:
1.1.C: No resizing. USM 150/2/3:
1.1.D: Resized to 6x4"@250ppi (my lab's recommended resolution) using the Bicubic (standard) interpolation method. No sharpening:
1.1.E: Resized to 6x4@250 using Bicubic Sharper method. No sharpening:
1.1.F: 6x4@250 Bicubic. USM 300/0.3/3:
1.1.G: 6x4@250 Bicubic. USM 200/0.5/2:
1.1.H: 6x4@250 Bicubic. USM 75/2/3:
Before we get into the real analysis, let's discuss and discard the first three. Those were the three where I didn't resample the file to the desired print size at the recommended resolution. If you don't work with the correctly-sized file, your sharpening is mere guesswork. You've got damn-all control over the result, because there's no predictability. God knows sharpening for print involves enough guesswork anyway ... you make it significantly harder for yourself if you don't even know what size the image is while you're looking at it.
Folk who say "Oh, just send the file to the lab without resizing it" don't give much thought to their sharpening. If you've read this far, I assume that you would like to give thought to your sharpening; so from now on, we'll only be discussing images which have been resized for print. I encourage you to read my article on this matter: The case for resampling. (Warning: it's boring!)
As it happened, 1.1.B actually turned out pretty nicely, but it was a pure fluke. If the composition had been different, or the focus, or the ISO, or any number of things, my arbitrarily-chosen USM values for that file would have been a bunch of junk.
Ok, back to business. I had five prints which had been resized before sending. 1.1.D had no sharpening, so it wasn't good enough for my taste. 1.1.E also had no sharpening, but I'd resized it with the "Bicubic Sharper" method which, as the name suggests, gives a sharper result than regular "Bicubic" method. But it still wasn't sharp enough for my taste.
(Some people love dabbling with the resampling method. They use "Sharper" for downsizing, and "Smoother" for upsizing. It's much too much hassle for me. You've got to choose it each time at the bottom of the Image Size dialog, and I keep forgetting, and anyway a lot of my resizing is done with the Crop Tool, which doesn't have the option natively, so you have to either change your PS preferences each time you crop, or do a two step crop-then-Image-Size process ... gaaaaaahh! It's all too hard, and I've never seen enough benefit to bother. I just stick to Bicubic, and avoid the headaches.)
1.1.F and 1.1.G were the winners in this batch. I was happy with both. Nice high Amount settings, nice thin Radius settings, and low enough Threshold settings to bring out those eyes beautifully.
1.1.H was pretty good too, but just not quite as good as the previous two. In hindsight, a lower Threshold setting would have been better, to bring out some sharpness in the eyebrows.
So there you go. 1.1.F and 1.1.G were the joint winners as judged by Yours Truly.
What do you see when you look at those two? Maybe you'd have thought there was a bit too much graininess in there? I can assure you that wasn't the case in the resultant print. Or maybe you think I'm too weak with my sharpening? Perhaps you love more? As I've repeatedly said, this is a game of personal taste - that's why I'm prompting you to do your own tests, and think for yourself.
PHOTO 1, SET 2
Same photo as before, but this time I resampled it to 12x18" @ 250ppi. I didn't get a bunch of 12x18 test prints made, of course! I got centre-cropped 6x4 prints done instead (using this method). I won't bore you with all of them, I'll just select a few.
1.2.A: No sharpening
Once again, the one without any sharpening didn't satisfy me.
1.2.B and 1.2.C were so darn similar I don't know why I bothered. I should have left the Threshold low on both, to really see some impact. As it happens, I instinctively liked both of those when I first looked at them. Whereas 1.2.D looked too strong when I first saw it.
BUT ... I had to stop and think. Was I really looking at a 6x4 print? Of course not - these were just sections of 12x18 prints. And do you look at a 12x18 the same way you look at a 6x4? Of course not. You look at a 12x18 while it's hanging on a wall.
Once I evaluated these test prints at arm's length, 1.2.D was the definite winner. What seemed too strong up close was lovely and crisp at a distance.
Lastly, I chose an out-of-focus photo. The kind of photo you'd print at 6x4, but no bigger. It was of similar composition to the other one:
I resized it to 6x4 @ 250, and started testing ...
2.A: No sharpening
Pretty obvious here - 2.C was the winner. 2.A was never a chance - some sharpening was desperately needed on this one. 2.B carried the same USM settings that had proved successful with the in-focus photo earlier, but they were inadequate this time. 2.C had sufficiently high Radius and Amount settings to bring out the best possible eyelash clarity - the best settings to make some kind of silk purse out of this sow's ear, you might say.
The Radius of 2 was just too wide for 2.D to be usable. On a 6x4, a Radius of 2 is getting more into defog territory than sharpening, and beginning to create visible halos under the eyelids etc. Not cool!
So, what have I taught you in this long and tedious post? Probably nothing - frankly, I didn't expect to. All I hope is that you'll take matters into your own hands and do your own testing. Maybe you won't even use Unsharp Mask at all; maybe you'll test a series of sharpening actions you've downloaded from various places. That's fine, as long as you are learning along the way.
Your test prints will probably be a bit more "all over the place" than mine were. Mine were all pretty tight, because I already knew what I was doing ... I've been sharpening stuff for a long time! In hindsight, I realise this post would have been more effective if I had thrown some really wacky settings in there to show the extremities of sharpening. I might do another one of these in the future.
For a couple of weeks, you might do test prints for all of your jobs, while you're getting the feel for sharpening. But of course that's not sustainable. It won't take long to develop a good instinct for nice sharpening at various sizes, and your confidence will grow.
All the best!