Lightroom (LR) plays a significant part of my work flow. A few years ago, I had tried the approach of using Nikon’s Capture for the process of RAW conversion, however since LR 2 came out, I have given up on using Capture. I choose LR for its DAM capabilities and the batch processing capabilities (and most importantly usability and speed factors). In any case, since its version 2 release, LR has had major changes in its RAW conversion capabilities – especially since it started using DNG profiles.
I however admit I have never been happy with ACR’s (LR) conversion of NEF images - especially when it comes to skin tones. In my quest to find a better conversion for my new D700 – I recently tried several converters – RAW converter, dcraw, Perfect RAW, Capture One, View NX/Capture NX2 & RAW therapee (via Parallels on Mac).
There are several factors that contribute to how the images are converted. On cameras that have the Bayer filter array, a specific process is followed in order to reconstruct the image. The part that differs between the various converters is the actual algorithms used for the de-mosaicing, de-noising, auto white balance determination, highlight recovery and tonal curves.
The differences in the final output is actually quite small – only the most dis-concerning eye can spot them…when you are specifically looking for these differences. Normal people – non purist types, non perfectionists & non-photographers will often not detect these differences. In fact, it is quite surprising how evolved the latest crop of RAW converters are and are all of them are perfectly suitable and do a very good job.
The below differences are based on the fact that i was specifically looking for these differences and fascinate me from a technical aspect, plus the fact that i am a purist.
So, here is a summary of my findings (All of my notes are with respect to the “Skin” tonality of the converter – not its general processing capability (artifacts, noise, sharpening etc…):
- PerfectRAW - This product is still in development (alpha stages). I found this application as possibly one of best RAW converters available. Unfortunately – this is in very early stages of development, and the version available today does not even allow one to save images. You can only view the images at this time.Perfect RAW is based on DCRAW. It improves on it – by implementing a custom demosaicing algorithm (called AFD), provides a full GUI with histograms etc. While it produces skin tones wonderfully. In fact DCRAW produces wondeful skin tones as well. DCRAW is available only via command line (limits its usefulness for most people), and while the others are GUI based, are not in the same league as commercial programs. The several derivates of DCRAW such as RAW Therapee, RAW Converter, UFRAW, and a few others in the same boat. While each of these products process RAW with a slightly variant algorithm – they are almost similar to most people (except for those of the pixel peepers tribes). Based on my analysis, i believe while the demosaicing results are variable betweeen these applications – they all use similar/same highlight recovery algorithms and linear tone curves – which may be the reason why the skin tones are very good.
- Capture One from PhaseOne is arguably my 2nd best converter of choice for Skin tones. It uses camera profiles from its very early days and the tonal characterstics of this converter is top notch. As a practical applicability in a workflow situation – I will have to weigh its usability. The question i keep asking is – is the conversion worth a round trip from my DAM application of choice (Lightroom)? Since Version 2.x of LR – i have found that LR has caught up and a round trip via Capture One is not efficient use of time.
- Capture NX2 obviously is the reference standard for NEF conversion. It obviously is the only RAW converter that can read every bit of the NEF format. Fact of the matter is that while the tool itself is excellent (control points is amazing), i am not thrilled by the default skin tone rendition of this tool as well. It is very slow, takes too much memory and clunky.
- Lightroom’s normal conversion is not bad for most of the images. In fact, the latest version (ver 2.4 at the time of writing) – is infact as good as it can get. With the use of DNG profiles – you can even custom tweak these settings. I do have several such profiles myself. In fact, i recommend every LR user to create custom camera profiles. Nevertheless, When it comes to skin tones – start with “Zeroed” settings & use “Neutral” profile as the starting point. If you create your own camera profiles – save the profile with a Linear tonal curve – and recover the highlights yourself via contrast curves within LR. These will provide the best skin tones (matches the PerfectRAW).
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