Creating a blur frame in Gimp


I had a chat with a friend of mine yesterday about photography and naturally there was a lot of equipment geek-talk. I realized (once again) that I’ve only got crap lenses to use with my D30, so when I came home I started browsing around for a pre-used lens. The requirements were (in priority order):

1) wide aperture (F1.8 – F2.8) and
2) wide angle (17/18mm)

I found a Sigma lens that would fit my needs perfectly. However, my wallet disagreed almost instantaneously. Okay, but let’s just see what the lens can perform. Googling around for some sample images, I stumbled upon an image with a blur-frame. I thought it looked interesting so I decided to postpone my lens-hunt and start fiddling with Gimp instead. The reslut, as you can se, is quite satisfactory.

The idea is to have two identical layers on top of each other. The lower layer will be manipulated in some way (in this case blurred) and the upper layer will be masked in some fashion to let the lower layer shine through. With this technique you can also create a nice-looking vignette-effect (by darkening the lower layer).

Ok, so this is how I did the blur frame above:

1) Open up the image in Gimp and create a copy of the “Background” layer (i.e. the whole image)
2) Select the upper layer and shrink the layer using “Layer boundary size” (the black border is where the upper layer ends)
3) Select the lower layer and apply a Gaussian Blur to the whole layer (I used a blur radius of 55 pixels)
4) Create a new layer on top of the lower image-layer and fill it with white
5) Adjust the opacity of the newly created white layer to about 15% so the blurred background will get a “white shine” to it

Now the basic blur frame should have been created using the whitened blurred background and a shrunk foreground image. For the drop shadow and black border, follow these steps:

6) Select the shrunk foreground image layer and choose “Script-Fu > Shadow > Drop Shadow”. The script will automatically create a nice drop shadow for you
7) Create a new transparent layer topmost in the layer stack and use the rectangular selection tool to select the “foreground area” (i.e. the whole visible foreground layer)
8) Stroke the selection using “Edit > Stroke Selection” (alternatively you can create a path from the selection and stroke the path)

That’s basically it. There should be some better way to select the “forground area” in step 7, instead of manually selecting it with the selection tool. Using “Select all” on the foreground layer will select the whole layer beyond the shrunk boundaries (instead of selecting only the visible area), which is quite odd in my opinion.



Filed under Geek speak, Photography

3 responses to “Creating a blur frame in Gimp

  1. Syster Yster

    Hej jag vill veta hur du gjorde det där! Har letat i Photoshop efter en sån feature. Vill inte göra ram dock utan blurra valda delar av bilder. Let me know.

  2. Ertan

    great tutorial, thanks

  3. Thanks for this valuable post. I love gimp.

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