In the last post, I used the patch tool to get rid of large blemishes. Let's take the same (stock) photo of a typical problem-skin teenager at the point where we left off:
The patch tool alone has made a big improvement, but there are still a lot of smaller blemishes that would take too long to eliminate that way, and the overall tone is too blotchy and uneven. "Skin smoothing" will help even it out. The most common method involves adding a blurred overlay made from the skin tone—the digital equivalent of foundation. Some people try to sell Photoshop actions with fancy names that do what I'm going to show you, but I'm calling it the "foundation" method because the result has the pros and cons of base/foundation/pancake makeup. Like a heavy layer of make-up, it hides flaws well, but it also risks making a person look unnatural. Way too many photographers who use this method lose all sense of restraint. Suddenly, they are children playing with their mom's makeup, and their clients, regardless of age or gender, end up looking like vaudeville performers. To avoid overuse, keep in mind that you are not really fixing their skin, you are just covering it up with a layer of makeup.
So here's how it works in brief: You make a duplicate layer, blur it (in various ways and levels of difficulty depending on who's teaching you), add a layer mask so you can paint out the blur in areas where you wouldn't put foundation, and then reduce the opacity of your "foundation" layer to achieve a balance between coverage and realism.
I used to follow a recipe that Scott Kelby calls "advanced skin softening." It goes something like this (and I'm going through it quickly and without all the material Kelby uses in his 12-step version, because I'm going to throw it all out in a minute anyway):
1. duplicate your background layer twice.
2. on one of the duplicate layers, add a heavy gaussian blur (I did 26 pixels here because it is not a big image, but 40 or higher can be pretty common):
3. Set the layer blend mode of your blurred layer to "darken":
4. Now repeat the blur procedure on your other duplicate layer (above the one you just did). Blur it to smithereens once again (I did 26 pixels again), but this time set the blend mode to "lighten."
Your darkened and lightened blend modes will look creepy and unflattering like this...
but in the next step, you will merge the two layers and end up with a plain old blur.
5. In the layers palette, click the eye to hide your background layer. Then, create a new empty layer on top of your two light/dark blurred layers. With your new blank layer selected, hold the option (alt) key while selecting "merge visible" from the layer palette's pull-down menu, and you will end up with a blend of your light/dark layers (which you no longer need and can now discard). All this gets you a skin colored "foundation" layer covering your photo. At this point, you will make the background layer visible.
6. So, your top layer is like heavy makeup—so heavy, in fact, that you may have to lower the opacity of the top layer to even see what you are going to be doing next, namely, masking out the effect anywhere that doesn't need foundation. The lips, for example:
masking out the effect is the magical part, but it's also a real pain. If you don't know how to mask, look at the thorough explanation in steps 5 and 6 of my clone out distracting backgrounds tutorial.
When masking, use the backslash key to show/hide a red overlay of what you are masking out:
I toggle between the normal view and this view constantly when masking so I can see if I'm missing a spot.
Lips are fairly straightforward, and even hair is not too bad, but the eyes need more attention.
The lines are clear on the inside of the eye, but the eyelashes and lids (not to mention the eyebrows) can't looked like they're caked in foundation. So you need to mask out each eyelash, one at a time—just kidding. Who's going to do that? The best way to deal with the problem is by changing the opacity of your brush (and use a very soft brush) and gradually take away the effect—more agressively around eyeliner and the parts of the lashes closest to the eye, more lightly where the eyelashes open out to the lids.
Bring texture back to the lids and the bottom of the eyes with low-opacity brush strokes.
When everything is masked that needs to be masked, you can view your makeup layer at 100% opacity and see how horrible it looks:
Then, you can lower the opacity. 68% still looks way too fake:
I have seen far too many skin retouch jobs that look like the image above. My advice is lower the opacity until you think it looks good, and then lower it a little more. Most people don't have flawless skin, and in the case of someone with problem skin, like this girl, you don't want to make her look like some frightening air-brushed glamor portrait. It's OK to let some imperfections show through.
At 36% opacity, she looks human again:
And now for the part where I throw out steps 1 through 5. In my opinion, all of that complicated darken/lighten/merge/blur stuff is overkill when you consider that you just end up with a blurry blob. But it's a quality blurry blob, some would argue. Maybe, but as an experiment, I decided to compare the results from the above process with this more simple process:
1. Duplicate layer and add a "surface blur" filter to it. The numbers don't matter, just the look. I put the sliders at 77 and 77 to get the following blur:
It looks about the same as the "foundation" layer I got from the lengthy steps 1-5 above. And you could probably get the same look by using gaussian blur filter. I just used "surface blur" above for fun because I hardly ever use it. In fact, I'm pretty sure Kelby does a short version like this with a gaussian blur.
2. There's no escaping the need to mask. Do the things I explain in step 6 and beyond to end up with a final result.
Here's the end result with the long way:
And here's the end result with the short way (surface blur version):
They are not exactly the same, but they are both acceptable.
If you want to try a longer version, my advice would be to buy Kelby's book (currently there's a CS4 one that is probably excellent like all of his work—the version I have dates back to Photoshop 7)—and turn the long method into an action to speed up the process.