Using GIMP: Correcting and Touching Up Your Images - GIMP 2.6 for Photographers: Image Editing with Open Source Software - page 69

The developing and correction of the image is now complete. The steps
until now represent developing a RAW image. The actual editing begins after
the handover to GIMP.
UFRaw does not offer a feature for sharpening images. You have to hand
the image over to GIMP first. A click on the icon with GIMP mascot Wilbur
at the bottom right does the trick. UFRaw shuts down and GIMP starts. The
image is then displayed in GIMP.
Click the Save tab if you just want to save the image. The edited image
will be stored as an 8-bit PPM file in the folder where you opened it. You can
select the file format under the Save tab.
You can, however, crop the image in UFRaw before you hand it over to
GIMP.
Crop and Rotate
The functions under this tab provide, as the name implies, the tools to crop,
rotate, and shrink your images. You can also flip the image horizontally or
vertically. I used it right in the beginning to set the picture upright.
Figure 2.11
The image is set at an aspect ratio of 13:18. In the preview window, you can see black beams on the left and right that indicate where the
image will be cropped. By clicking the left mouse button on the preview image, you can determine the section to be cropped.