How To Sharpen Your Headshots The Right Way
Why We Sharpen
Have you ever been shooting a headshot session and every time you look at the back of your camera the images look tack sharp only to find out later when you look at them on your computer monitor they aren't as sharp as they seemed? You missed focus by a little bit. Or maybe you were shooting in low light and had to drop that shutter speed down to get a little more light but you ended up with a bit of motion blur. And of course, these particular shots just happen to have the best expressions, poses, and lighting. This is where sharpening can help a little. And I do mean a little. This is by no means a cure for extreme cases but has certainly helped me bring back images that were otherwise unusable. And hey, if sharpening won't work, you can always convert to black and white. Then it's just artistically blurry. Am I right? C'mon, you know you've done it. Also, I should note that even when I nail focus I still sharpen my images a little.
Get Into The Habit
Something I've learned to do more often when checking images on that tiny LCD screen is to zoom in all the way to the eyes and check my focus. This saves me the headache of more post work or more artistic black and whites.
So here goes. The method we're going to cover will give you a lot of control by separating your sharpening between dark and bright areas. We're going to use an image I shot in the studio a while back that I believe is the worst motion blur you can get away with and still render a sharp image with this technique. You may be able to get away with something slightly worse but I wouldn't push your luck. The area you want to pay the most attention to are the eyes. More specifically the eyelashes. Here you can see that they're defined but they're not sharp.
Open your image up in Photoshop and duplicate it (ctrl+j). This should become a habit in your workflow. This is your safety net should you need to start from scratch and it's a great way to have a look back and see if you've gone to far and overedited your image.
Zoom into your image until you're at a 50% zoom level, annotated at the bottom left of the interface. Select your top layer if it isn't already selected. Go to the "Filter" menu at the top of the interface. Select Sharpen > Unsharp Mask.
In the Unsharp Mask dialog box you're going to crank the amount all the way up to 500%. The Radius will be adjusted at your discretion based on your image and the Threshold will stay at 0. Over time you will find what works well for you. For now I will show you where I generally set things. The trick is to go just far enough that you start seeing the highlights turn a little glittery.
Start with the Radius at 0.9. For this particular image a Radius of 0.9 is too high.
Adjusting it to 0.4 works perfect and sharpens the image nicely. Hit OK.
Now, before you do anything else, and this is crucial, go to Edit > Fade Unsharp Mask.
In the Fade dialog box, change the mode to Luminosity. This will prevent the sharpening effect from saturating the colors in the sharpened areas.
Next, you're going to set the top layer's blend mode to Darken. This is where you will gain control over the sharpening in the dark areas of the image. Rename the layer to Darken.
Duplicate the Darken layer (ctrl+j) and change the duplicate layer's blend mode to Lighten. This will give you control over the light areas of the image. Rename the layer to Lighten.
Now it's time to control your sharpening. Generally I like to reduce the Lighten layer as this shows the most obvious signs of an over sharpened image. You do this by reducing the opacity of the layer. 66% looks pretty good to me. I will usually leave the darken layer at 100% and reduce both layers together. You do this by grouping the layers (select both layers and hit ctr+g) together and reducing the opacity for the group. I've set mine to 70% and renamed the group to Sharpen.
You can take this one step further by adding layer masks to your individual layers and masking out the areas you don't want to be as sharp.
Before and After
Here's a before and after with the results. You can see that this has greatly improved the sharpness and overall quality of the image.
If you have any questions add them to the comments below and I'll do my best to answer them.