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How to sharpen any image in Photoshop

  • There’s a bunch of different ways to sharpen an image using different tools and different filters.From Unsharp Mask to High Pass filter, to sharpen tool and using Camera Raw. The biggest challenge is to know when and why should you use some over others or sometimes mix them.
  • In this tutorial, we learn different techniques for sharpening images in photoshop. so, you can use any image that’s in need of some sharpening.

The original photo before sharpening with the High Pass filter

How To Sharpen Images With The High Pass Filter

Step 1: Convert The Background Layer Into A Smart Object

When using the High Pass filter to sharpen an image, the best way to work is to apply High Pass as a Smart Filter. This keeps the sharpening effect separate from the image itself and avoids making permanent changes to the original photo. To apply High Pass as a Smart Filter, we first need to convert the Background layer into a Smart Object.

If we look in the Layers panel, we see the newly-opened image on the Background layer. Click the menu icon in the top right corner of the Layers panel:

Clicking the Layers panel menu icon in Photoshop

Clicking the Layers panel menu icon.

Then choose Convert to Smart Object from the menu:

Choosing the Convert to Smart Object command in Photoshop

Choosing “Convert to Smart Object”.

Photoshop converts the Background layer into a Smart Object and names it “Layer 0”:

The Background layer is now a Smart Object in Photoshop

The Background layer is now a Smart Object.

Step 2: Select The High Pass Filter

To apply the High Pass filter, go up to the Filter menu in the Menu Bar, choose Other, and then choose High Pass. This opens the High Pass dialog box which we’ll look at in a moment:

Choosing the High Pass filter from under the Filter menu.

Going to Filter > Other > High Pass.

What Is Image Sharpening?

To really understand why the High Pass filter is such a great tool for sharpening images in Photoshop, we first need to understand how image sharpening works. After all, we don’t physically sharpen pixels the way we’d sharpen a set of knives. So what does “image sharpening” even mean?

Much like any good magic trick, image sharpening is an illusion. It works by increasing contrast along the edges of objects in an image. Photoshop can’t recognize specific objects, of course, so it considers an edge to be any area where there’s a big, sudden change in brightness or color between neighboring pixels.

Increasing contrast along the edges makes the light side of the edge lighter and the dark side darker. Your brain then sees the increased contrast as “sharper”. The more we boost the edge contrast, the sharper the image looks. But really, image sharpening has nothing to do with “sharpening” pixels. Instead, it’s all about increasing edge contrast.

Why Use The High Pass Filter To Sharpen Images?

So if we sharpen images by increasing edge contrast, what does that have to do with Photoshop’s High Pass filter? Well, before we can increase contrast along edges, we first need to find those edges, and that’s where the High Pass filter comes in. High Pass is an edge-detection filter. It looks specifically for edges in the image and highlights them. Areas that are not an edge are ignored. Once we have the edges highlighted, we can then combine the High Pass filter’s results with one of Photoshop’s contrast-boosting blend modes (as we’ll see a bit later on) to easily increase contrast along edges without affecting the rest of the image.

Step 3: Find The Edges

The High Pass filter’s dialog box is very easy to use. There’s a preview window at the top and a Radius slider along the bottom. As I mentioned, the High Pass filter detects edges in the image. The Radius value controls how much highlighting to apply to those edges. Any areas that are not an edge are filled with neutral gray.

The easiest way to use High Pass is to start by dragging the Radius slider all the way to the left, to a value of 0.1 pixels (the lowest possible value):

Starting with the lowest Radius value in the High Pass dialog box

Setting Radius to the lowest value.

At the lowest setting, the entire image is filled with solid gray, with no edges visible anywhere. That does not mean there are no edges in the image, or that the High Pass filter is not able to detect them. The problem is just that the Radius value is too low at the moment for the edges to be seen:

Photoshop High Pass filter results using the lowest radius value

At the lowest Radius setting, no edges are visible.

To bring the edges into view, begin dragging the Radius slider to the right to increase the value. I’ll increase mine to 4 pixels:

Increasing the High Pass radius value to highlight edges in the image

Increasing the Radius value.

If we look at the image, and in the preview window in the filter’s dialog box, we now see faint highlights around the edges. Here, we see them around the owl’s feathers and other features, as well as along the tree branch. Other parts of the image that are not considered part of an edge remain solid gray:

Increasing the High Pass radius value reveals edges in the image

Increasing the Radius value reveals edge detail.

How The Radius Value Works

I mentioned earlier that the Radius value controls the amount of highlighting that’s applied to the edges, but that’s an oversimplification. What the Radius value actually does is it determines how many pixels on either side of an edge should be considered part of the edge. For example, a Radius value of 1 pixel would mean that Photoshop would include only a single pixel on either side of the edge; one pixel on the light side and one pixel on the dark side. But if we increased the Radius value to, say, 10 pixels, then Photoshop would extend the width of the edges to 10 pixels on either side.

That explains why we couldn’t see the edges when we initially lowered the Radius value down to just 0.1 pixels. Photoshop was including only one tenth of one pixel on either side of the edges, making the width too narrow to notice. But when I increased my Radius value to 4 pixels, Photoshop extended the width of the edges out to 4 pixels on either side, making them wide enough to be easily seen.

Pushing The Radius Value Too Far

When using High Pass to sharpen images, be careful not to push the Radius value too far. The reason is because too much of the image will be included as part of an edge. Watch what happens if I increase the Radius value to something extreme, like 40 pixels:

Increasing the High Pass filter Radius value to 40 pixels

Setting the Radius value too high.

At a Radius of 40 pixels, Photoshop is extending the width of the edges out to 40 pixels on either side, and now pretty much the entire image is considered part of an edge. We’ve gone from subtle highlighting against an otherwise neutral gray background to a weird embossed effect, with large halos visible everywhere:

The image with the High Pass radius value too high

An example of what happens when we increase the Radius value too much.

Finding The Radius Value Sweet Spot

Remember, sharpening works by increasing contrast along edges without affecting any other areas. So for the best sharpening results with the High Pass filter, choose a Radius value that’s just large enough to bring out the highlights while keeping those highlights as close to the actual edges as possible.

The exact Radius value you need will depend on your image. Larger images generally need larger values than smaller images to achieve the same results. In general, Radius values of between 1 and 5 pixels tend to work best. For my image, I’ll go with 3 pixels. Click OK to accept your Radius value and close the High Pass dialog box:

Setting the High Pass filter Radius value to 3 pixels

Lowering the Radius value to a more reasonable 3 pixels.

At this lower setting, the image is back to being solid gray for the most part. The edge highlighting is visible but subtle. This is the result we’re looking for:

The image with subtle edge detection using the High Pass filter and a low Radius value

The High Pass result using a Radius value of 3 pixels.

Step 4: Change The High Pass Filter’s Blend Mode To Overlay

Now that the edges are highlighted, the next step is to increase the edge contrast by blending the High Pass filter’s result into the original image. We do that by changing the blend mode of the High Pass filter. In the Layers panel, the High Pass filter is listed as a Smart Filter below “Layer 0”. Double-click on the Blending Options icon to the right of the filter’s name:

Opening the Blending Options for the High Pass filter in the Layers panel

Double-clicking on the Blending Options icon.

This opens the Blending Options dialog box. The Mode option (short for “Blend Mode”) is at the very top. By default, the blend mode is set to Normal. To use our edge highlighting to boost contrast along the edges, we’ll need to use one of Photoshop’s contrast-boosting blend modes. There’s a few of them to choose from, but the one that usually works best for image sharpening is Overlay:

Changing the blend mode of the High Pass filter to Overlay

Changing the blend mode of the High Pass filter to Overlay.

The Overlay blend mode hides any areas of neutral gray, so all of those non-edge solid gray areas created by the High Pass filter instantly disappear from view. It then uses the lighter highlights to lighten the light sides of the edges even further, and the darker highlights to darken the dark sides. This boosts the contrast of the edges and creates the illusion of a sharper image.

Here’s a before-and-after comparison to help make the sharpening effect easier to see. On the left is what the original image looked like before any sharpening was applied. On the right is the result using the High Pass filter and the Overlay blend mode:

A side by side comparison of the image before and after sharpening with the High Pass filter in Photoshop

A before (left) and after (right) comparison of the sharpening effect.

Trying The Soft Light And Hard Light Blend Modes

If the sharpening effect from the Overlay blend mode is too strong, try the Soft Light blend mode instead. It works exactly the same as Overlay but the results are more subtle:

Reducing the sharpening effect by changing the blend mode of the High Pass filter to Soft Light

Soft Light creates a less intense sharpening effect than Overlay.

Or, if the Overlay sharpening effect isn’t strong enough, try the Hard Light blend mode. Hard Light will give you the most intense sharpening of the three:

Increasing the sharpening effect by changing the blend mode of the High Pass filter to Hard Light

Hard Light creates a more intense sharpening effect.

Here’s a side-by-side comparison of the High Pass filter set to all three blend modes, with Soft Light on the left, Overlay in the center and Hard Light on the right. The Overlay blend mode is generally the one you’ll use the most:

A comparison of the sharpening effect using the Soft Light, Overlay and Hard Light blend modes. Image © 2016 Photoshop Essentials.com

The Soft Light (left, least intense), Overlay (center, average) and Hard Light (right, most intense) blend modes.

Step 5: Lower The High Pass Filter’s Opacity If Needed

Finally, regardless of which blend mode you choose, you can fine-tune the sharpening amount even further by adjusting the opacity of the High Pass filter. You’ll find the Opacity option directly below the Mode option. The more you lower the opacity from its default value of 100%, the more the original, unsharpened image will show through. Once you’ve chosen the blend mode that gives you the right amount of sharpening for your image, and you’ve adjusted the High Pass filter’s opacity if needed, click OK to close the Blending Options dialog box:

Adjusting the image sharpening amount by lowering the High Pass filter opacity

Lowering the opacity of the High Pass filter.

Step 6: Toggle The Sharpening On And Off

The easiest way to judge if you’ve applied the right amount of sharpening to your image is to compare the result with how the image looked before it was sharpened. To view the original, unsharpened version, click the High Pass filter’s visibility icon (the eyeball icon) in the Layers panel:

Toggling the image sharpenin effect on and off using the High Pass filter visibility icon

Clicking the visibility icon for the High Pass filter.

This temporarily hides the sharpening effect, revealing the original image:

The original photo before sharpening with the High Pass filter in Photoshop

The original image before sharpening.

Click the visibility icon again to turn the High Pass filter back on and view the sharpened version:

The image sharpened with the High Pass filter in Photoshop

 

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