Bite-Size PS Tutorials: Sharpening with High Pass Filter

Bite-Size PS Tutorials: Sharpening with High Pass Filter

Two things converged for me recently: an increase in questions sent to me regarding my commercial photography and the unexpected popularity of my bite-sized Photoshop tutorials. Both occurrences are born from the same inquiry of understanding how certain things are achieved. I used to bother people constantly with questions on how I could attain a certain look in post-processing, or how an image is so sharp, and so on. From time to time, I still do. So, I'm going to do my best to make the answers to the most common questions readily available with this mini series.

I'll start with my usual caveat. This collection of brief tutorials are not for you veterans photographers and retouchers. With that in mind, here is a quick round-up of the tutorials in this series so far:

Why Sharpen with the High Pass Filter?

In my early days of photography, I'd look at my images, then at a top photographer's infinitely sharper images and I would misjudge the reason for the chasm. As a result, I would stand on the clarity slider in Lightroom until it screamed out in distress, followed by some sharpening through Photoshop to finish it off. Once I realized that Spinal Tap's advice on amps isn't pertinent to sharpening, I dialed it right back. But the truth is, sharpening in post is important and because it can be done in a number of different ways, some thought ought to be put in to which method you use.

When I'm looking for the optimum technique in any form of post-processing my images, I'll see what the top retouchers use. I've mentioned this before in my tutorials but this group of e-artists are excellent for sniffing out the best way to squeeze out quality from an image and although the ones I've spoken to sometimes use more than one technique, the High Pass filter is their go-to. There are a number of reasons for this but the chief motivation for most is that a High Pass filter will be a separate layer and not interacting directly with the pixels of your image. This is often referred to as a "non-destructive" form of editing.

One important thing to always remember about sharpening is that contrary to what the methods are called, sharp images are made in camera, not in Photoshop. All you're doing it bringing out the details that are already there and you should be doing so subtly.

How to Sharpen with the High Pass Filter

Firstly, I'm going to provide a step-by-step text tutorial as it's easier to navigate should you miss a step:

  1. Create a stamp visible layer of your image so far using Shift+Ctrl+Alt+E on Windows or Shift+Command+Option+E on Mac.
  2. Control+J/Command+J to duplicate the stamp visible layer.
  3. Navigate to the top menu Filter > Other > High Pass
  4. Enter the value 3.5 pixels (This is trial and error but 3.5 is by far my most common value).
  5. Set the blending mode of the layer with the High Pass filter applied to "Overlay."
  6. Delete the layer below the layer with the High Pass Filter applied as it's no longer necessary.
  7. Add a layer mask and fill it with black. Then paint in the areas you want to be sharper with a white brush.
  8. Lower the opacity of the layer to suit your tastes. I usually end up somewhere between 50% and 90%.

Step 1

Create a stamp visible layer of your image so far using Shift+Ctrl+Alt+E on Windows or Shift+Command+Option+E on Mac. This will put all of the work you've done on the image so far in to a single layer, similar to if you were to save the image in its current state as JPEG (etc.).

Step 2

Duplicate the new stamp visible layer. This duplicate will become the sharpening layer.

Step 3

Navigate to the top menu Filter > Other > High Pass to apply the filter to the top layer.

Step 4

Here I enter a value of 3.5 pixels but this is trial and error. In my experience, 3–4 pixels is about right, sub-3 and the sharpening becomes negligible and would not be noticeable unless the image is viewed on a very large scale. Anywhere around 5 and further north and the image becomes contrasty, grainy, and minute blemishes in your image become pronounced. If you're not sure, stick to 3.5.

Step 5

Set the blending mode of the layer with the High Pass filter applied to "Overlay."

Step 6

Delete the layer below the layer with the High Pass Filter applied as it's no longer necessary.

Step 7

Add a layer mask and fill it with black. Then paint in the areas you want to be sharper with a white brush. As you can see below, I sometimes use varying brush opacity, flow, and hardness. I often want certain areas to be sharper than others even though they are both in focus to add slightly more (and I do mean slightly) emphasis on to the subject, in this case, the watch. On occasion, I only paint in the details of the subject and leave things like the watch face masked. This is time consuming but can be useful if there are plain uniform surfaces that are getting noisy when sharpened.

Step 8

Adjust the opacity of the sharpening layer to suit your tastes and image. I would say my most common value is 60–70% but it can vary from 50% through to 90%. This value is highly dependent on the quality of the image going in. If it's a bright, well-exposed image shot at low ISO with few shadows, you can get away with even 100% at times. If it's a low-key image with higher ISO, be vary careful going above 60%.

Here is a 100% crop before and after of the above image. The changes are very subtle and they're meant to be. I realize that this method of showing the effects is flawed as the example images are scaled down, but nevertheless this is the method I use in almost all of my images. Pay particular attention to the Henry London logo in the below example.

Here is another example where I used the technique to bring out the detail in a subject's eyes.

Log in or register to post comments

15 Comments

You can also play with blend mode, Soft Light and Hard Light offer slightly different looks.

Sergio Miranda's picture

The value of High-Pass to be put is called Radius and it will depend on the size of your file. The bigger the dimensions of the file, the higher the radius. At the same time, it will depende on the subject you are photographing. For example, photographing a person, if it's a face closeup it will be different that if it's a full body portrait.

I use a radius of around 9px for my 36MP files and 5 for the 24MP camera.

Jorge Tamez's picture

If you use frequency separation, you can increase contrast to the high frequency and do a high-pass sharpening that way. the benefit is that it's just an adjustment layer and you get to see the results in real time.

Evan Guttman's picture

I use a simple action that I downloaded for my frequency separation. Can you give me a bit more details on how I would add the contrast and do a high pass sharpening? Thanks

Kirk Darling's picture

This is actually what we did with film called...unsharp masking.

Paolo Veglio's picture

As already pointed out, the high pass radius depends on the image resolution...

On a separate note, I don't understand step 2. Once you created the stamp visible layer you can apply the high pass directly to it, there's no need to duplicate it.

Grant Schwingle's picture

I believe step 2 and 6 are unnecessary.

Thomas Jergel's picture

If you convert the new "Stamp Visible" Layer to a Smart Object you can quickly and easily change the High Pass radius without going about the hassle of reapplying the filter.

Clever way to preview your settings as well.

Some resources also recommend desaturating the high-pass filter layer before proceeding to the next step of blend mode adjustment and use of additional layer masking technique to limit this adjustment to a certain area(s) of your image. It's supposed to prevent potential color shifting/sharpening, but honestly I haven't noticed any of that happening during my workflow.

Daryl Watkins's picture

So if I have 30 DNG images that I've edited in LR, I'd still need to open each one in PS, apply the high pass sharpening and then saving it...creating another 30 files?

red cat's picture

excellent bite-size tuto :) thanks a lot !

Taylor Franta's picture

Quick hint: apply aggressive noise reduction to the high pass layer. It will help avoid sharpening smoother textures which usually show up at noise/ grain.

Robert K Baggs's picture

This is a very interesting idea. I will experiment with this later. Thanks Taylor.

This is nice to know.
But one should notice that basically this is what the USM is doing.

In Image Processing most Sharpeners are done using addition of inverted Low Pass Filtered variation of the image.

Specifically, for sharpening, there are much more advanced algorithms out there.
I wouldn't use the basic stuff when there are much better choices.