I've had a lot of comments recently about how people like my "frame in a frame" presentation, so I thought I'd document the (manual) process here for those who are interested.
I use The GIMP, but much of what is required will apply regardless of the application you are using, as long as it is capable of creating LAYERS. There is a GIMP Script-fu preset for the frames, probably converted from a similar preset for Photoshop, but the manual way works as well and is almost as quick once you have the steps in your head. So ... here we go!
Select your image and open it in your chosen editor. The translucent frame treatment is nice for isolating a subject but, like anything else, it should be used sparingly and in the right situations.
I'm going to use a nondescript shot of a pigeon as my example for this tutorial. It has a lot of distractions in the foreground (leaves, twigs, ciggy butt, etc). It also has lots of lines that take the viewer's eye out of frame. If I crop to remove the bulk of these problems, while trying to retain the same scale and form factor, I could lose the bird's tail on the right edge which is already slightly out of shot anyway. Instead I need to isolate my subject without losing its context.
Create 2 additional copies of your image by using the layer duplicate tool (circled), then rename the top 2 layers "Foreground" and "Mask" respectively. In GIMP that's achieved by right clicking each layer and choosing "Edit layer attributes". The foreground layer is going to be used as the subject layer in the final image and the mask layer is going to provide the translucent border treatment to the original background image. Remember, the layer duplicate tool may look slightly different, or be called something else, in your editing software but it will perform the same task.
Select the "Mask" layer by highlighting it and add a LAYER MASK to the layer; chose "white (full opacity)" fill option from the layer mask dialog box. When the mask appears in that layer, click the image in the "Mask" layer with your mouse pointer to select that and use the BUCKET FILL tool to fill the frame with black. Then use the opacity slider in the layers area to set the layer opacity to 50%. You should end up with something like this in the layers tool area.
Almost there. Click the "Foreground" layer with your mouse to make that the active layer, and use your selection tool to select the area you want for the main subject. Try to leave about 80 pixels on each edge for the underlying transparent frame. Then use Layer>Crop Layer to crop the foreground to your selection. You should see the transparent border come out from behind in the remaining area like this:
Phew! Made it! With the cropped "Foreground" layer still selected, choose Select > Border ... and set the selection to have a 3 pixel width border. Then use your flood fill tool to fill the selection border with black or another colour of your choice. That will give your subject layer a solid border to force the viewer's eye to remain mostly inside the inner frame while still allowing the viewer's brain to know that there are other parts outside that it doesn't need to be concerned with. The end result should look something like this: