[published february 2007]
DXO: Digital Problems, Digital Solutions
Once upon a time, the photographer’s work was done when the shutter curtain fell. Now it’s just beginning.
The digital age has somewhat diminished the role of the ‘shutter monkey’ in today’s busy studios. Supervised creatively by Art Directors, in technical matters they are likely to defer to the post-production staff, to whom the captured image – frequently images – are merely the starting point for the final shot. As part of this trend, contrast the proliferation of tools for processing images with the paucity and simplicity of tools available to capture them with.
Consider the undisputed champion: Photoshop – an application’s whose toolset grew so large that it became its own genre: five entirely different versions are in circulation and more plug ins are available for it than there are types of accounting software, or known varieties of dim sum.
Many of these target the dwindling number of specific tasks not presently handled by Photoshop: automated colour correction, sharpening, lens aberration and distortion correction, volume anamorphosis, weird file formats, ugly/gratuitous special effects, etc. It’s not easy being a PS plug-in developer: as soon as you develop some desirable new gadget, along comes Adobe like some Spherized supermarket chain and incorporates your distinctiveness into the Collective.
A market persists, though, for specialised tools claiming to outperform Photoshop in certain areas. RAW development is a good example: as late as CS2, Adobe’s RAW software was only going through the motions. But the RAW Shooter engine in CS3 and Lightroom is arguably good enough – in terms of features and image quality – to push Silky Pix, Capture One, Bibble, RAW Developer, DPP, et al out of the market. And the new HDR format provides the kind of innovation that we’ve previously relied on third party developers to deliver.
When it comes to image manipulation (stitching and panorama creation, fisheye rectilinear conversion, CA elimination, noise reduction, and complex geometric aberrations), we find a number of small developers still doing what Photoshop – currently – cannot. Helmut Dersch‘s high quality interpolation routines have provided a backbone for a powerful and low cost suite of applications aiming to provide profiled corrections for many commonly occuring lens problems.
Taking this approach one step further, DxO Optics is a very smart, fully profiled application with targeted corrections for specific lenses. It knows, for instance, that when you shoot a 24-105mm f4 L IS on a Canon 5D with a subject at distance of 3m, at f4, that the image will have a certain, predictable amount of vignetting, barrel distortion and chromatic aberration. It also knows that some of these problems with be exactly X% less severe at f5.6, f8 and f11. And that if you use the same lens on a 400D, your troubles will be slightly different. Apparently ‘automatically’ it corrects the exposure, perspective, CA, and selectively sharpens and resamples the image accordingly.
I know of nothing that makes a better job of automated colour correction that this utility. Even if you do nothing else with it – and I don’t, for reasons which I will explain in a moment – this alone practically justifies the ticket price. Its USM facility is smarter than Photoshop’s; it has a great ‘film emulation’ function; the ‘Lighting’ controls are very sophisticated, and it does fisheye and VA correction. You may have read Ken Rockwell’s glowing review and be tempted to rush off and buy it immediately . . . but, without wishing to dissent too far from his report, it would be wise to consider a few of its weaknesses before parting with a substantial wad of cash. I didn’t, and within a week was begging for a refund. Having failed to extract my money from DxO, I have reluctantly come to terms with being a DxO user and have even found a niche for it in my workflow. Here’s the trouble . . .
RAW Processing: If Capture One scores 95% for image quality, and Raw Developer scores 93%, DxO’s raw processing algorithm would score about 70%. As of versions 4.x, this remains its Achilles’ heel. No matter how great DxO is at tweaking and fussing with the image post-processing, the base conversion is poor: noisy and splotchy. You bought the application for maximum image quality, yet you can’t let it touch your RAW files. This creates a rather major difficulty, because it doesn’t seem to have occurred to anyone there that the engine might not be very good – DxO really likes to get at all that information locked up in EXIF to make the best job of the conversion. If you decide (as I did, at first), to produce 16-bit files in C1, then hand them to DxO for final polishing and correction, the program de-activates all the critical corrections: no CA control, no distortion control – in fact, no recognition at all of the lens you used, which means you don’t get the benefit of any of the months they spent fettling the defects in your 24-105L. DxO blames C1 for not preserving the full EXIF data in its output files. Phase permits users no control over this in the Preferences.
Lens Support: Ken appears to have had great success with the Canon 15mm and DxO, but forgot to explain that the only fisheye supported for all those lovely corrections is the Canon 15mm. Use a Zenitar 16mm, Sigma 15mm, or even a Zeiss 16mm and you’re on your own, son. To be fair, DxO is profiling new lenses all the time, and the company does have a sane upgrade policy . . . but all the same: check very carefully that your exact body and lens combination is supported before buying. And if you’re planning on extracting a little more from your adapted Nikon, Olympus, Zeiss or Leica lenses, you’re out of luck. Or maybe not . . . read on.
Fisheye Correction Quality: It appears from the massively downscaled samples show in Ken’s review that the quality of the converted file is barely degraded from the original. This is far from true. Even if you use just the right lens, corner performance in particular (where maximum resampling inevitably occurs) is significantly worse than using a rectilinear lens of a similar focal length – like the Sigma 12-24mm. Though DxO usually comes up trumps with CA correction, Ken’s images show strong CA visible in web-res’d full frame images – imagine what that looks like at 100% ! Comparing my full version of DxO with the trail version of Image Align, using a test shot taken with a Zeiss 16mm Fisheye (which you’re not supposed to be able to use in DxO: see later for the workaround!) it was immediately obvious that Image Align makes a much better job of the translation. Its scaling tool also allows you to choose how you trade off between image size, image quality and field of view. Having said tha, Image Align is a dedicated – and expensive – single purpose tool, whereas DxO adds useful features like Volume Anamorphosis correction into the mix.
Speed: DxO is a real resource hog, and is sometimes mind bogglingly slow, both to update file lists in the ‘Select’ pane, preview effects in the ‘Enhance’ section and ultimately to process files, especially if it does the RAW conversion.
It’s not all caveats, though. Forced to coexist with it by DxO’s refusal to let me stop being a customer gracefully (or acknowledge the application’s shortcomings) we’ve learnt to get along – a bit like an arranged marriage between a 12 year old and a middle-aged alcoholic that begins with ritualised humiliation, mutual loathing and beatings, but which over the years matures into unspoken contempt, benign indifference, and ultimately into cosmic acceptance and a kind of folk wisdom, prior to the onset of senile dementia and death – in which at least there is peace. In other words, I develop everything in C1 and use DxO solely for colour correction.
Then again, revisiting DxO with my fisheye head on, a workaround occurred to me: there is a way of getting access to all those powerful correction tools, even when using adapted lenses. This revelation struck me while I was making holes in the table leg with my Doc Marten’s as I realised that I couldn’t use the much cheaper but equally good Sigma 15mm fisheye because DxO only supports the Canon version. I thought: ‘why not pretend the Sigma is the Canon?’ One 15mm fisheye has much the same profile as another: lots of CA in the corners, predictable degree of simple distortion over a 180° field of view . . . what’s good for the Canon is good for the Sigma, right?
And if I can fool DxO into thinking the Sigma is a Canon, I could also get it to think that a Nikon 17-35mm is the same as a Canon 17-40mm – both have precisely the same complex distortion characteristics which are impossible to correct fully in PS. And then I thought: what has similar distortion characteristics to a Zeiss 21mm and Leica 19mm? And then I thought: OK, how do I do that? I was only thinking these things, incidentally, because I do own DxO and I do not own the much cheaper PanoTools suite which does all this stuff without breaking sweat.
The Solution
So here’s one way to use DxO with any lens – on an Apple Mac at least. To persuade DxO to correct a non-Canon fisheye:
• Get ExifTool from here . . . Install it. It’s free. Why not give Phil some money?
• Place your Zeiss 16mm fisheye RAW file in the top level of the active user’s folder (with ‘Desktop’, ‘Documents’, etc). We’ll assume the file is called cz16.cr2
• Place a Canon 15mm RAW file in the same folder. Rename it 15mm_donor.cr2
• Open Terminal: don’t be afraid.
• Key in: exiftool -all= -tagsfromfile 15mm_donor.cr2 -exif:all cz16.cr2
A copy of the original file will be saved alongside your new EXIF-spliced RAW file. When you open the new cz16.cr2 with DxO it will think it was shot with a Canon 15mm, and all those previously hidden correction tools will become active. You’re not stuck with Canon-specific corrections, and can tweak them for the Zeiss. Actually, it doesn’t make a bad job of it right out of the box.
The same method will work for any lens: find a donor RAW file from a lens in the DxO database with similar properties to the one you want to use, place it in the active ‘User’ folder, invoke ExifTool to FrankenSwap the EXIF data, and DxO won’t see through the disguise. The same Perl-powered software works on the PC: in fact there’s a proper interface which makes it even easier. You can use the ExifTool to edit, swap , import, export and generally tinker to your heart’s content with all embedded image file data.
In Conclusion
If DxO’s colour correction and USM wasn’t so damn fine, I’d recommend spending a little more on Image Align to de-fish and/or PanoTools/Lens Fix for everything else. However, with certain (fairly serious) caveats – a bit like a piping hot fresh apple and cinnamon crumble with roasted pecans, coconut and lashings of proper vanilla custard that’s been left on the side for about 30 minutes on a summer’s evening, with a skin on the topping and the middle not quite cool – DxO can be lukewarmly recommended in its current iteration as a total workflow tool that falls just short of its aim, but one that is truly peerless at extracting maximum vibrancy and bite from your images, providing you first process them in another application.
September 2007 Update:
The goalposts have moved somewhat in recent months: ImageAlign is no more – presumably superceded (but not quite eclipsed) by CS3 Warp – rather as predicted above. But now we have DxO v5 on the horizon, promising vastly improved RAW processing and all the same colour goodness. Watch this space for a C1 v DxO5 head to head . . . .
