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Sharpening photos quickly with the High Pass Filter

I rarely used to sharpen my photos in post processing. I never needed to... Just a standards "for the screen" sharpening during Lightroom Export to JPEG was enough for me. However, I discovered recently how easy it is to sharpen photos in Adobe Photoshop using the High Pass Filter. Still I don't sharpen every photo I produce but if and only if I go round-robin from/to Lightroom then Photoshop I found it useful to do so especially if I am planning to print the photos. Always remember that printout need a little bit more sharpening because of the soft edges printers produce.

But which sharpening filter is better in Photoshop? High Pass, Unsharp Mask, or Smart Sharpen? Well, there are many ways to sharpen a photo in Photoshop but this tutorial is about doing it quickly without bothering about details and advanced features. Maybe I will post another article regarding the other two methods. Remember though that the High Pass Filter method has 1 slider and it works on the mid-tones. Furthermore, any areas that is not a color edge is left intact.

Enough said, let's jump straight into the tutorial.

Step 1 - Duplicate the Background Layer 

You should start making this a habit by now! Sharpening filters usually are pixel destructive adjustments in Photoshop. So create a layer copy of the background layer by hitting Ctrl + J (on PC) or Cmd + J (on MAC).

Step 2 - Change the blending mode

The high pass filter turns all areas that are not color edges into neutral grey. So to leave those areas alone we are going to change the top layer blending mode to "Overlay", which means no sharpening will be applied to those areas. Go to the Blend Mode options in the top left corner of the Layer Palette and click on the drop-down options to change the blending mode from "Normal” to "Overlay". Don't worry about the harsh contrasty edge it produced. We will change that after applying the filter. The reason we did that in the first place was to see a preview of the sharpening being applied.

Step 3 - Apply the High Pass Filter

Next, go to the Filter menu and choose Other - High Pass. This brings up the High Pass filter dialog box. Really, there is nothing to it; just a preview box with -/+ zooming option and a slider called Radius. But be careful as we don't want to over-sharpen our image. 

To sharpen your photo, adjust the Radius value by dragging the slider left and right while keeping an eye on the preview window and the canvas to see what edges are being sharpened. Drag to the right and you will be adding more sharpening. Drag to the left and you will be reducing the amount of sharpening.

Start off with a very low radius value, somewhere between 2-5 pixels depending on the pixel dimensions of your image. So if your initial photo is a RAW file you can safely go up to 20 but if you are working on a reduced JPEG version of your photo, then stay in the range of 1 to 5 pixels. If you go too high, a halo will be clear around the color edges and that looks nasty, but go ahead and play around with it just to explore its effect.

Step 4 - Change the layer blending Mode again 

“Overlay” blend mode is the “average” amount of sharpening. If you want to increase the sharpening amount, change the Blend Mode of the Layer to Hard Light. If you want to lower the sharpening, change it from Overlay to Soft Light. You can also change the Opacity to reduce to overall effect. Usually around 80% works well. Furthermore, if you decided to apply the sharpening to a local areas within the photo, you can hide the layer with a black layer mask and paint over with a soft white brush the areas you want to reveal.

That's it! It is now your turn to sharpen your photos. Remember though if you are sharpening for printouts, you need to increase the effect a little bit more... Enjoy!

Un-sharpened photo as shot in the camera. See the soft edges between the flower and the black background and on water droplets...

Photo after applying High Pass Filter in Photoshop