TechRecipes

A raw image file is a supposedly un-processed image file taken directly from the image sensor of a digital camera. Depending on digital camera manufacturers, a raw image file is stored using various file extensions such as NEF, CRW, SRF, DCR, and ORF.

While manufacturers normally bundle RAW image editing software along with their digital cameras, the software most likely doesn’t run in Linux. Popular third party software such as Adobe Photoshop or Apple Aperture doesn’t run in Linux as well.

This however doesn’t mean that it’s not possible at all to do the RAW image file processing in Linux, as there are alternative softwares, and they function just well.

1- Dcraw

This is a very feature rich command line based program that is actually the backend for few other GUI based RAW processing programs. While being useful for being able to be scripted for easy batch processing, there’s no way to preview the RAW image other than to see the finished products and that makes it less appealing for most users.

The following is an example on how to convert a RAW image

dcraw -n 150 -H 5 -w -q 3 -b 1.5 DSC_1704.NEF

with the followings are explanations on each of the option switches;

• -n 150 : Set the noise threshold to 150 (possible value is from 100 to 1000)
• -H 5 : Reconstruct highlights as a compromise between whites and colours
• -w : Use white balance specified by the camera
• -q 3 : Use Adaptive Homogeneity-Directed (AHD) interpolation.
• -b 1.5 : Set the brightness to 1.5
• DSC_1704.NEF : The RAW file

Running the following command will create a .ppm file which can be opened and edited by popular photo editing software such as The Gimp.

2- Ufraw

This is probably as of now the most popular RAW image editing software in Linux. Even though that it has quite a funny name (which ufraw actually stands for Unidentified Flying Raw), it’s actually a tool for serious people.

Ufraw is a very mature program for this purpose. The program provides many options for RAW image processing, and the user interface displays a lot of useful information. Ufraw however doesn’t have photo directory browser which makes it a bit hard to work on many images at once. Ufraw is available as a standalone program and as a plugin to the popular image manipulating program for Linux, the Gimp.

3- Rawstudio

Rawstudio is known to be an easy program to operate. By trying to be easy, the program lacks many options as compared to Ufraw. All is not lost however as the program itself in some ways are more desirable when compared to Ufraw.

The program comes with the default dark interface which is easier in the eyes when working with photos. It also displays thumbnails of photos in particular directory, making it easy to navigate between photos while working on multiples photos. Rawstudio also comes with split-screen mode to display two versions of the same photo side by side.

4- Rawtherapee

Rawtherapee can be considered as what we get when combining the best of what Ufraw and Rawstudio has to give.

It has a very intuitive interface, a lot of options that we can play with (more than Ufraw), directory browsing with thumbnails, and a very good workflow. I consider this as my personal favorite and would recommend it to anyone.

The only drawbacks of this program that I can think of is that though it’s a free software, it is not open source. We also need a big screen to comfortably use the program.