Using GIMP: Correcting and Touching Up Your Images - GIMP 2.6 for Photographers: Image Editing with Open Source Software - page 51

If your digital camera offers its own propriety software, or its own RAW
format, you should use it. The possibilities of post-processing the image,
especially when the images taken during special light conditions (such as
backlit photographs, pictures taken at dusk, etc.), are much better when
they are taken in RAW format. You should also store the images in this
format as originals on your computer in order to save them in high quality.
The operating system's file management utility can also show RAW formats
as preview images. Windows, for example, can do this, but only after you
installing the corresponding codecs. Microsoft offers the codecs for several
camera manufacturers on its website at http://www.microsoft.com/prophoto/
downloads/codecs.aspx. Similar raw codecs for the Windows operating
system can also be downloaded from the FastPictureViewer website : http://
www.fastpictureviewer.com/codecs/. A nother option would be to have a look
in the support section of the camera manufacturer's website.
2.2 Opening and Developing a RAW
Format, or Digital Negative , with GIMP
GIMP can open most but not all RAW file formats offered by camera
manufacturers. As a start, you can use GIMP for editing these images directly,
but only with a color depth of 24 bits (8 bits per channel). However, if you
want to develop your digital negatives with the original color depth of 16 bits
per channel (rather than 8 bits) in order to make fine-tuned corrections and/
or print a higher-quality photo, you'll have to depend on the RawPhoto or
UFRaw plug-in. Once you've integrated one of these plug-ins into GIMP, it will
automatically become active when you open a RAW file with GIMP. Let's first
take a look at the UFRaw plug-in since it can be installed at a later point in
time, as described in section 1.4.5.
UFRaw can be used in three different ways. If used as a GIMP plug-in,
when you open a RAW file in GIMP, the UFRaw window will automatically
open. You can set corrective options for color and brightness values in the
preview window. This lets you develop and correct your image before even
opening GIMP.
You can simply click OK on an open image to load it into GIMP. Then
you can use GIMP's tools for corrections—a legitimate practice. However,
the UFRaw program supports a color depth of 16 bits per color channel. This
allows you to make detailed adjustments, whereas using GIMP's familiar tools
limits the color depth to 8 bits/channel.
In addition, UFRaw can be used as a stand-alone program for developing
digital negatives. During installation, the program creates a desktop icon or
a Start menu entry on demand. With the UFRaw stand-alone, you can save
images in the PPM, TIFF, and PNG file formats with 8-bit or 16-bit color depth