Wednesday, January 23, 2013

Sharp as a Bag of Wet Towels

Is there a term more widely, vaguely and euphemistically thrown around by photographers than "sharpness?" This lens is sharp. Every photo needs some sharpening. Sharp between F2.8 and F9. Tack sharp. In Lightroom 3 there are at least 7 sharpening-related settings I can think of off the top of my head, and if you ignore them can make excellent photos.

What gives, yo? Why is this so important?

Many great things aren't sharp (hello, Monet?), and how is sharpening different from focus? I've been largely ignoring the settings in Lightroom for years, only using them when trying to recover a photo that's a touch out of focus or at a high ISO.

I've come to a conclusion - I need to read up on the principles of sharpening and figure out whether this is an elaborate hoax propagated by ignorance (e.g. tapping on the top of a soda can to reduce fizz), or actually a valuable part of my imaging tool belt. about digital-photography bandoleer? Yeah.


Take a couple photos that are already good and try to improve them significantly with the sharpness settings in Lightroom.

Overview of the Settings and Jargon


There are four basic sharpening settings in Lightroom 3 in the Detail window, grouped logically and more-or-less undefined unless you read a tutorial:

  • Amount - Slider that sets the "amount" of sharpness. The only obvious part of this. At 0 everything is blurry; at 100 everything is "posterized," which essentially means "fugly."
  • Radius - The distance from a strong edge, in pixels, that will be sharpened. 1 is the default and it seems generally ideal, but for fine things (e.g. grass) you might go smaller. I've yet to find a good example of why >1.5 is desirable. Best idea seems to be to leave this setting alone unless the image is of an extremely detailed/undetailed subject.
  • Detail -This affects the degree to which minor edges are excluded from sharpeneing, where 0 sharpens only major lines and 100 sharpens all shapes. Seems that the idea is to start low here and slowly increase the detail until there's enough definition in the details of the image.
  • Masking -Very fancy setting, as it sets a threshold on the image where only relatively stronger edges are sharpened. At 0 you sharpen everything, while at 100 only the edges of major shapes are sharpened.
Related settings include holding down ALT to get a preview of the tools (see links at the bottom for more info on this), and noise reduction, which reduces noise with some cost of detail (i.e. you should sharpen some to compensate).

Example 0 - How to ruin a photo

This is what happens if you "posterize" a photo with too much sharpening. Also, the subject is a moron.

This same moron over-sharpened himself in Lightroom

Don't do this.

Exercise 1 - Nice portrait, normal ISO. Fixing something that's not broken.

Here's a thoroughly adorable photo I took of Leah in the kitchen. You can't tell, but she's got a mouth full of banana.

Why am I sharpening this one? Well, it's supposed to be important. Let's see if I can improve on something that's essentially sharp as far as I can tell. And trying to improve things that are already non-broken is a bit of a family tradition, but historically there wasn't a CTRL-Z.

Note: By default, Lightroom does some sharpening, it's just not masked and at a fairly low level. I did some noise reduction to begin with as I'm cropped way in here.


Default Lightroom sharpening (no masking)


Additional sharpening, including a mask set at 50

Seriously people, when I had a super-duper zoom on areas like her chin and eyes, I was making an improvement. I don't think anyone has looked that carefully at the Mona Lisa.


Don't worry about sharpening if you don't have noise, detail or focus issues. Go pet a cat or make a sandwich.

Exercise 2 - Slightly out-of-focus, high ISO portrait

This is one of my all-time favorite photos - a 31-yr-old me with his 31-day-old daughter, credit to Meg for the camerawork.This is printed out on my desk at work, but I never felt I quite got it right and it's been sitting unchanged in my catalog for over 2 years. Here are my gripes:
  1. Leah's head is a little out of focus, which is unavoidable for F1.8
  2. The highlights on the faces were lost due to the high dynamic range. Though somewhat recovered it leaves the edges of the faces a bit soft.
  3. Adding sharpness added noise, and reducing noise reduced sharpness. It's hard to find the best combo.


Default Lightroom sharpening


The best I could do to get this sharper

Try to ignore the edges, as they stayed about as sharp as I could get as I applied the mask. Where I made the most improvement was in reducing noise in other areas, such as around the mouth. In short, applying a mask lets you get things a little sharper, but mostly protects the rest of the image from being ruined.


Sharpening doesn't do as much as you would think, or at least Lightroom does a really good job without you needing to take the yoke from the autopilot. You are more likely to be able to limit the bad parts of sharpening than get make significant improvements.


After all this putzing around with sharpening I'm left thinking that Lightroom is doing pretty darm well in this dept without my making any changes. Not to say that I won't mess with sharpening on occasion, but it's unlikely that I'll be able to save a terrible photo or make changes to a keeper that someone would notice consciously.

I believe that the digital photo gurus out there know what they are talking about, so I'll keep experimenting with other types of images (landscapes?) to see if there are more places where the sharpening controls will make a difference.


I read the following webpages as part of this process. Citing sources like a champ.
Digital Photography School

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