How To Use the Sharpen + Blur Tool in GIMP {Complete Guide}

The Blur + Sharpen Tool are like oil and water! You could say they’re on the opposite end of the photo editing spectrum. It’s not that difficult to decipher what the tools do since their names tell you exactly what they’re used for. So…

…in this tutorial, you’ll take a deep dive into both tools; you’ll discover their tool options and how to use them to edit your image (s) like a pro. If you’re ready… let’s do it!

What Is the Blur Sharpen Tool?

Photo by Ali. To sharpen or to blur? That is the question. This image demonstrates both tools… and how they are overdone. Not recommended. Knowing how to apply these tools selectively is the key to a natural edit.

The Blur Sharpen tool was designed to, well, blur or sharpen your image. There are other ways to do both in GIMP. You can use a Filter to find numerous ways to blur your image, like Gaussian Blur, Lens Blur, and Motion Blur, to name a few. There’s also a filter or two for sharpening your photo as well.

The difference between the filters and the Blur Sharpen tool is the latter gives you more control! Filters, by design, are used to apply a global edit to your image. In other words, your entire image will be blurred. Unless, of course, you also utilize a Layer Mask.

With the Blur or Sharpen tool, you can apply your adjustment precisely where you want it. This is done since both tools are applied with a brush!

GIMP Blur Tool + Sharpen Tool Options

One tool two different results. Instead of creating two separate tools, the GIMP developers combined both into one. The way you use one or the other lies within the Tool Options. To activate the tool, use Shift + U or find it in the toolbar.

Since you’re applying the tools with a brush, you’ll have many settings to consider first. Check out the Paintbrush guide for detailed info on each of these settings. For the Blur/Sharpen tool, there are only 3 main settings that are new compared to the other Paintbrush options…

A handy-dandy keyboard shortcut is the Command (mac) or Ctrl (pc) key. This auto switches the tools from one to the other!

How To Use the Blur Sharpen Tool in GIMP

Using either the Blur or Sharpen tool is straightforward. If you want to blur a part of your image, paint over the area. Increase or decrease the intensity as needed. Ditto for sharpening. Here are some additional pro tips…

Blur

If you find some elements of an image distracting the viewer, you can selectively blur it out. Try not to blur it too much, though. Otherwise, it will look unnatural if the surrounding area is sharp and your object isn't. In this case, you'll need to increase the size to be blurred to blend it in with other parts of the image.
If you have a large area that needs to be blurred, you might be better off with one of the blur filters.
When applying the blur tool, the direction of the brushstroke has no effect. If you need directional blurring, try using the Smudge Tool instead.
To some degree, the blur tool can soften pimples, scars, and other blemishes. However, it might be better to use it in conjunction with the Heal Tool or Clone Tool.
Work non-destructively by applying on a duplicate of the image layer.

Sharpen

In essence, sharpening with this tool increases the contrast where the brush is applied.
The result of increasing contrast too much will result in the dreaded Digital Noise. Therefore, apply sparingly.
As with the Blur tool, use a duplicate of the image layer to apply. In fact, if you're blurring and sharpening for the same image, I'd recommend applying one on the copy. Then create a duplicate of that layer to use the other.
Using duplicate layers to work on also gives you the ability to adjust the edit's intensity by lowering the Opacity (if needed)!
For better results, you may want to consider using the Unsharp Mask filter and a Layer Mask.

Pro Tip

Using the Clone Tool and an Unsharp Mask filter can provide a sophisticated method for achieving controlled sharpening. Here’s how…

First, duplicate the image layer you want to work on.
Next, apply your preferred sharpening filter. Personally, I use Unsharp Mask.
Grab your Clone Tool (C), and in the Tool Options, set the following options: Source = Image Source and Alignment = Registered.
Set the Opacity to around 10 - 20. Adjust as needed.
Next, Ctrl-click on the duplicate to make it the source image.
As you paint on the original layer, the pixels will mix together with the sharpened and unsharpened version.

What's Next?

The Blur and Sharpen tools are essential for precisely controlling where your edits are applied. But are they the best option in your toolbox? That depends on your editing needs. To find out for sure, you’ll have to learn about other tools in GIMP to compare them to.

Ready to elevate your GIMP image editing skills? If so, you’ll be amazed by these free tutorials. Oh, and don’t forget these too.