What if I told you that sharpening as we know it in photography isn’t real? That might be a little hard to believe but the truth is that it is actually impossible to make an image physically sharper after it has already been made. Sharpening a photo is simply an illusion. We can make a photograph appear to be sharper. Our digital images can be made to look sharper by adjusting the contrast of the pixels around the edges of shapes within the photo and this is what we are going to talk about today. We will look at how you can easily make your photos more sharp quickly using the high pass filter in Photoshop.
What is the High Pass Filter?
The high pass filter is just a method of creating a sharpening effect to your photo based on the pixels surrounding the contrasted edges of the elements within the image. While Photoshop has some dedicated sharpening tools(unsharp mask, smart sharpening) the high pass filter is the method I tend to use the most because I love the total control it gives me over my sharpening.
Using the High Pass Filter
To get started with sharpening using the high pass filter it is highly recommended that you complete ALL of your edits prior to performing the sharpening. This means that if you’re like me and do most of your processing in Lightroom and then export to Photoshop for finishing you will leave your high pass sharpening for the very last step. When you’re ready to sharpen, open your image in Photoshop.
Next, duplicate the layer by using keyboard shortcut Ctrl+J(Cmd+J for Mac). This is the layer where the high pass filter will be applied. I’ve renamed it “High Pass Layer” so it’s easier to see.
Make sure the new high pass layer is selected and then click on the ‘Filter’ tab and then ‘Other’ and lastly select ‘High Pass’.
You’ll notice an abrupt change to your image. It will essentially go completely grey. Don’t panic because this is exactly what we want to happen. But we have a choice to make and that is what radius we set for the high pass filter.
The radius controls the amount of pixels which are targeted around the edges where the sharpening will be applied. There’s a lot of wiggle room here and it generally is based on the resolution of your camera. The higher megapixel your camera the higher you can set the radius without causing unsightly effects such as halos and glowing edges. Let me show you what I mean. Here is the high pass filter with a radius of ‘1’…
And now here it is with a radius of ‘36’.
The higher the radius the more of the image will be affected. This particular photo was made with a 36.4 megapixel camera and I find a radius of ‘4’ to be the proverbial sweet spot. Adjust your radius accordingly.
Click ‘OK’ to apply the high pass.
But wait, this still looks horrible and gray and not at all what we want.
The next step is key. We have to change the blend mode of our sharpening layer. There are multiple choices here but the ‘Overlay’ option tends to work best with virtually all images and is the blend mode I use. After the overlay blend mode is selected we have what is essentially our final sharpened image.
Have a look at the difference the high pass filter has made in terms of sharpness. Here is the unsharpened photo….
And now the freshly sharpened version….
Closing Thoughts on Sharpening with the High Pass Filter
Don’t forget, not only can the high pass filter be applied easily but like any other layer adjustment in Photoshop the opacity can be adjusted until you reach the exact level of desired sharpness. Furthermore, adding in a layer mask to the sharpening layer can allow you to take complete control over the sharpening effect and only apply it to the areas of the photo you choose.
The best bit of advice when it comes to sharpening an image using any method is that less is usually more. Always remember that an over sharpened image is often less appealing than one that is slightly soft. Enjoy using the high pass filter in Photoshop!