Four DNG (GXR raw format) developers for Linux compared

Started Feb 12, 2011 | Discussions thread
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Pangloss
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Four DNG (GXR raw format) developers for Linux compared
Feb 12, 2011

Hi,

Since I only use Linux, I have limited access to the variety of Windows software available to post-process RAW files. But actually Linux is rather well-endowed when it comes to software that can read DNG files, which is Ricoh's choice for their RAW format for the GXR (and Ricoh is to be commended for that choice).

My first tests were with UFRaw which is a relatively easy to use utility, but rather limited in image editing capabilities. In particular, it has a very basic denoising algorithm and I have noticed it introduced some color artifacts in some images.

Below you have approximately the same crop of a test image I have been using lately, developed with four different programs, as well as the out of camera JPG with some comments in each case.

Let's start with the out of camera JPEG . Note that I haven't yet changed the GXR's default JPEG settings.
Whole picture scaled down to 25%:

The problem with the JPEG version is that it's slightly too dark and the colours aren't right. Nothing that can't be fixed in post-processing, but if I am going to PP an image I'd rather work on the DNG file. On the other hand the following 100% crop shows that the in-camera JPEG engine does a good job at denoising and sharpening:

Next is a program called DarkRoom . This one is rather easy to use, but there are just basic controls over image quality. Still, it did a good job cleaning up the noise, but... somehow the overexposed patch in the window got translated to a bright green. Ugh!

The crop shows the good denoising, however there is also a loss of contrast in the blue plate above the mascaron.

Next is UFRaw . After some trial and error I managed to get the "right" (to my taste at least) colours and contrast out of UFRaw.

However the crop shows that UFRaw has a weak denoising algorithm. Besides, the white 2 number on the blue plate has some red shadows, which I believe are artifacts produced by UFRaw. That's bad!

Next is another program called RawStudio . It also has a rather simple interface with the usual, simple controls, and I managed to get more or less the colours and contrast I wanted.

The denoising algorithm is also average, as you'll notice some residual noise left in the dark patch under the number plate. But at least no artifacts!

Finally we have RawTherapee . Now RawTherapee is not only a RAW developing program, it has tons of options, a steep learning curve and (imho) a rather awkward user interface. BUT it has an excellent denoising algorithm and all the image editing options one could ask for. After wasting 15 minutes fiddling with various controls, I managed to get the image I wanted:

As for the crop, it shows the best denoising of all the developers used here, but no better than the in-camera JPEG engine. Note that RawTherapee can also do some sharpening as it develops a photograph, and it can be used for batch processing as well as organising photo archives.

My (personal) conclusion: for the odd image and just to check out what an image looks like, I can use the out of camera JPEG or a simple DNG viewer/developer. For serious post-processing in Linux, RawTherapee is the best choice.

C&C welcome!
--
Andrew
Panasonic LX3, Ricoh GXR w/ A12 28&50mm user

 Pangloss's gear list:Pangloss's gear list
Panasonic Lumix DMC-LX3 Nikon D200 Ricoh GXR A12 50mm F2.5 Macro Ricoh GXR GR Lens A12 28mm F2.5 Nikon 1 V1 +4 more
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