Here’s a short method to allow you to highlight a subject in an image while blurring out the remainder of the photo. You can experiment and control how blurry you’d like to make the background/non-focused area. There are a few different ways to get this effect, so keep that in mind and use what works best for you.
For these methods, I will assume that you have GIMP installed and that you are capable of finding and opening your image before attempting the changes.
To see larger versions of the images, click them so they can load in a new tab.
Feel free to comment with your experiences in making a blurred background image in GIMP.
1. Open your image in Gimp
2. Duplicate your image layer into a new layer and hide your original image layer. We will save it in the event we need it. If you want, name your new layer as “Blurred”.
3. Select the “Blurred” layer and click Filters on the menu bar. Click Blur, Gaussian Blur. Set the radius values to 25 and click OK. Change the value based on how your photo appears in the Preview window. Each photo is different and may need some experimentation to find something that works well.
4. Duplicate your original image again into a new layer, and name this layer “Working”. Move it above the blurred layer. At this point, the “Working” and “Blurred” layers should both be visible.
5. Add a new layer mask to the “Working” layer. Right-click the layers and choose “Add Layer Mask”. On the dialog window for the mask, choose “Black (full transparency)” and click Add.
7. We’re going to show the large penny in full detail, but keep everything else blurry. Choose the paint brush in the toolbox and paint the area that you want to be in focus. The remainder will remain blurred. Watch your edges and zoom in as needed to paint carefully on the penny to make it visible. If you make a mistake painting, choose black as the paint color and re-paint the problem area to return it to being blurry.
8. After you finish painting the focus area to show through the blur, you can choose File, Export As to save it as an image.