Ever had an image that didn’t look tack sharp at 100%? Don’t worry. It happens and it’s normal. Luckily, you can learn how to sharpen an image in post-processing.
Sharpening an image is one of the basic things to learn when you want to start editing photos.
In this article, I’ll show you how to sharpen an image in Adobe Photoshop.
Things to Know Before You Sharpen a Photo
There are a few things you must know about sharpening an image in Photoshop.
Limits of Sharpening
There are limits to the amount of sharpening you can apply. Every digital image needs some amount of sharpening but you can’t make an out of focus photo seem in focus.
It’s not possible.
You’ll learn when a photo is too far gone by using the sharpening functions.
Halos and Noise
When you apply too much sharpening effect, halos will appear around edges. At some point, it’s noticeable that you sharpened an image and it looks ugly.
For the same reason, you should apply filters like noise-reduction before you sharpen the image. Sharpening will make noise more visible.
Separate Layers and Medium
The best way to sharpen an image in Photoshop is by using separate layers. Depending on the final medium, you’ll need different amounts of sharpening.
Make separate layers for print, screen, and so on.
How to Sharpen an Image in Photoshop
I’ll show you how to sharpen an image using Unsharp Mask and Smart Sharpen. These are the best sharpening filters in Photoshop. Both give you more control than the other filters.
Unsharp Mask is my favourite sharpening filter because it doesn’t increase noise.
You might think Unsharp Mask is a weird name for a sharpening filter. The name comes from a dark room technique.
The ‘Unsharp’ in the name derives from the fact that the technique uses a blurred image. That negative image creates a mask for the original.
This is then subtracted from the original to detect the presence of edges. Contrast is then selectively increased along those edges using this mask. The result is a sharper image.
Now, let’s sharpen an image in Photoshop. I’ll use this photo I took in India for the first example.
Step 1: Open the Photo
Open the photo you want to sharpen. Right click on the background layer and select ‘Duplicate Layer…’.
A new window will pop up. Click OK. The new layer will appear on top of the Background layer.
Set the blend mode of the new layer to ‘Luminosity‘. This will prevent any colour fringe around edges.
You need to apply the sharpening on this new layer.
Step 2: Apply Sharpening
Try Unsharp Mask first and Smart Sharpen on a new layer or different photo. Never apply both on the same layer.
1. Unsharp Mask
Zoom in to 100%. Go to Filter > Sharpen and select ‘Unsharp Mask…’. The Unsharp Mask window will appear.
Make sure to select the Preview option and that you can see the different parts of the image you want sharper.
You can see the effect of sharpening both in the little preview thumbnail and on the photo in your working area.
The Amount slider sets the amount of sharpening. Usually, any digital photo file needs around 60% of sharpening for screen viewing.
If you want to make large prints, you can go anywhere from 100 to 200.
The Radius determines the number of pixels surrounding the edges that affect the sharpening.
The greater the value, the wider the edge effects and the more obvious the sharpening will be. Around 1 or 2 is fine for most photos.
Use the Threshold slider to prevent effects like posterisation and colour changes. Unless you’re using high amounts of sharpening, you can leave this slider at value 0.
When sharpening for print, it can take some trial and error before you know the right settings. It depends on which camera you have, sensor size, print size, etc.
2. Smart Sharpen
Remember to use this filter on a new layer or try it on a different image. You never want to use two different sharpening filters on the same image.
Zoom in to 100%. Go to Filter > Sharpen and select ‘Smart Sharpen…’. The Smart Sharpen window will pop up.
Make sure to select the Preview option and move the window out of the way.
Set Amount to a value of around 150% to start with.
You can leave Radius usually at a value of 1 or 2. I always start with 1.
Unlike Unsharp Mask, the Smart Sharpen filter has a noise reduction slider. Use it when noise starts to become visible after sharpening.
Use the dropbox Remove to set the algorithm Photoshop will use to sharpen. Gaussian Blur is what Unsharp Mask uses.
Lens Blur will apply a finer sharpening and reduces halos. Motion Blur will try to remove blur caused by camera or subject movement.
You can set the angle next to the drop-down menu.
Use the sliders under Shadows / Highlights to remove light or dark halos in case they appear too strong.
Play around with the settings at high values to see what they do and how they affect the look of your entire image.
Again, every camera file or final medium needs different amounts of sharpening.
How to Sharpen Selectively
If you don’t want to apply sharpening to the entire photo, you can use selective sharpening. Use a mask to only sharpen the eyes of a person for example.
Here’s how to do that. I’ll use a portrait I shot in India.
Step 1: Open the Photo
Repeat the previous STEP 1 for the picture you want to sharpen selectively.
Step 2: Apply Sharpen
Also repeat STEP 2 and apply sharpening to the new image layer.
Step 3: Add a Layer Mask
Make sure to select the top layer and click on ‘Add layer mask’. A white mask thumbnail will appear next to the layer thumbnail.
The white represents areas of the layer that are visible. At the moment, all areas of the sharpened layer are visible.
Step 4: Hide the Sharpened Layer
Select the paint bucket from the toolbar and make sure the colour is set to 100% black. Click anywhere in the image.
It seems like nothing changes but the mask thumbnail is now black. That means the sharpened layer is no longer visible.
Step 5: Paint With White
Select the Paint Brush from the toolbar and pick a soft brush. Make sure the colour is set to white and the mask thumbnail is selected.
Start painting over the eyes or any other areas you want to sharpen. Paint on the image, not the mask thumbnail.
Painting with white will reveal the hidden areas of the sharpened layer again.
This allows you to sharpen only the part of the image that need sharpening. For example, in portrait or fashion photography, the skin doesn’t need sharpening. Only the eyes need to be sharpened.
You can still apply more sharpening to the masked layer if needed. The sharpening will only be visible in the areas you’ve painted white.
Sharpening in Photoshop is something every photographer has to learn. Every digital photo file needs some amount of sharpening. It all depends on the file and the final medium.
Be careful with the amount of sharpening you apply. High amounts of sharpening will make your images look unnatural and ugly.
And never rely on Photoshop to save an image that’s out of focus. You can’t make an out of focus image sharp.