Friday, July 25, 2014

Post Processing: RAW Editors and Dynamic Range

If you have been a photographer for a while you have likely read discussions about dynamic range, and how modern cameras have more than older ones. This becomes apparent if files are saved as jpegs in camera, but even more so when shooting in the RAW file format. While that is true, the RAW editor used can also affect the usable dynamic range of a file as well. Some RAW editors work better with cameras of a given brand, while others just have superior algorithms for a given task. The only way to know what editor works best with the files you have is to test them.

To demonstrate the abilities of several different editors, here is a file that has a few things wrong with it. The lower half of the image is partly underexposed, and the highlights in the sky are on the very edge of being blown out. While this is not a worst case scenario, it is getting very close. If I had shot this photo as a jpeg it would have been a write off, without a doubt. In some ways the original file looks worse the the "unedited jpeg" below.

While the edits from various RAW editors are posted below, I would like to see what others would do to this file in the RAW editor of their choice. Thus I am making the original .NEF available for download (for personal use only, no commercial use permitted). Note that this is a 14bit lossless compressed file from the Nikon D800, and is about 40MBs. Post a link to your edits on flickr, or photo sharing service of your choice, and post a link in the comment section below. Let us know what editor you used to work with the file.

Unedited File (JPEG crated by Capture NX-D)
Once again starting off with an unedited jpeg file created in Nikon Capture NX-D, just to show how bad the original file is. All of the following files are edits of the original RAW file. The as shot white balance (in camera "Cloudy" preset/approximately 5500k) is maintained in all edits. As with last weeks images I applied similar curve adjustments to all files and corrected chromatic aberrations and barrel distortion as able.

Edited In Capture NX-D 1.0
The file edited in Capture NX-D is not much different from the original, besides correcting chromatic aberrations and barrel distortion. No amount of working with the exposure curves could save the file in that application, and applying different picture controls only made matters worse. Capture NX-D is very limited, and truly amounts to a quick and dirty way to convert RAW files to jpegs or TIFFs for those who like the, right out of camera look, or for later editing in other software.

Adobe Lightroom 5.5
Lightroom 5.5, with Adobe Camera RAW, is a far more powerful editor, and the results speak for themselves. The ability to use brushes, curves and other advanced tools made editing the file in Lightroom far more rewarding than Nikon's Capture NX-D. I was able to easily pull detail out of the underexposed sections of the image, and recover the highlights as well. Lightroom also outputs far nice colours than Nikon's software.

Aperture 3.5.1
Here is the file edited in Aperture 3, which is more powerful than Capture NX-D, but also lacking in some areas as well. The weaker sharpening, and chromatic aberration reduction tools reveal themselves, along with the inability to correct distortion. Noise in areas recovered from the shadows is also more apparent (see larger file). It is well known that Aperture's RAW editing tools are somewhat dated, and it shows when you do not use third party plug-ins to enhance the files. Since Aperture is on deaths door I did not want too spend much time working on this file. None the less I was able to pull back the shadows and highlights a reasonable amount, and improve the colours.

darktable 1.4.2
With darktable I once again found myself working with a powerful RAW editor, at least when compared to Capture NX-D and Aperture 3. Darktable may be open source software, but it is no slouch when it comes to shadow and highlight recovery. In fact darktable is right in the same territory as Adobe Camera RAW in this regard. Where darktable falls a little short is saturation and vibrancy controls, which is disappointing. You need additional software to do touchups and the like anyway, so that is not a deal breaker.

RawTherapee handled the extremes of the exposure rather well, but the highlight and shadow recovery tools do not seem as powerful as darktable or Lightroom though. Like darktable, RawTherapee seems to come up short when it comes to enhancing the colours in the image, but again this editor is more of a first step tool than a finishing tool.

Google Nik Collection
For this final image I took a different approach, but it required moving out of a non-destructive editor along the way. The first step in this case was to bring the file into Capture NX-D and apply distortion correction and remove chromatic aberrations. Next the file was exported as a 16bit TIFF and edited using Google's Nik Collection. I started in Viveza 2 to apply the desired curves, contrast and saturation. Following that the file was edited in Nik Color Efex Pro 2, where I used the Detail Extractor, Foliage, Pro Contrast and Graduated Neutral Density filters.

Using this workflow is a little more time consuming, since you have to jump between several programs, but the end results are basically on par with those coming out of the non-destructive RAW editors. The downside is that each edit you make to the TIFF file is destructive, and there is no way to go back a step once adjustments are saved to the file.

Each one of these editing methods seems to offer something a little different. Part of the process is simply learning how far you can take a poorly exposed image without totally destroying it. I think the files above demonstrate that shooting RAW can be extremely helpful for those times that you make a mistake in camera. Being able to work on a file like this can be extremely important, particularly when you don't have a tripod and need to capture as large a range of light as possible. If I had been using a tripod I could have taken a series of photos and use an HDR method, but I did not so the file shown was the result. 

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