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Raw Power – the DxO converter

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Raw Power – the DxO converter

Review: DxO Optics Pro V2
A new way of converting your camera’s raw files

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Earlier in 2004 Keith reviewed the DxO lens correction software and found that despite its powerful correction functions, it would be of limited use since he invariably uses his camera’s raw format when taking pictures.

A new version of the program (DxO optics Pro 2 and the DxO RAW Engine) that does raw conversion as well as the lens correction is now here.

dxo histogram

Keith has been looking at it both from a conversion quality point of view, as well as how he could include it in his day to day working.

This article was originally in 2 parts – now combined.

Why would I want another raw converter?

I’ve discussed some of the reasons for using raw format in another article but it is mostly for the quality of the image produced.

Adobe have included the excellent ‘Camera RAW’ (ACR for short) in Photoshop CS. I use it a great deal, and once you understand the numerous options available in advanced mode it is very powerful. In particular you can use it with the file browser and scripting (see Dr. Browns Image Processor).

Whilst reviewing some of the several thousand images I’ve taken this year I’ve been noting those that although they might potentially make good prints, they just didn’t live up to expectations when I started working on them.

The second reason for using raw format, is that you can always go back when new software becomes available…

Many of the examples in the article are from raw files that just didn’t work as well as I wanted. In the course of my testing I discovered that even some of my minor complaints about the Canon 1Ds might not be all down to the camera.

In this review I’m looking at the DxO Raw Engine being used with DxO Optics Pro 2. All test images were shot on a Canon 1Ds. The software was run on a Dual 2.5GHz G5 Macintosh (3GB ram, OS X 10.3.6) The software also runs on PCs…

What does the software do?

At its simplest the software converts raw files to Tiffs and can additionally correct distortions in images. You can have 8 or 16 bit output and attach any ICC profile you might want to the images (defaults are sRGB and Adobe98)

I’ve discussed the distortion side of things in the previous review, so I’ll just mention them briefly here

There are four areas of your image that the software currently addresses:

  • Geometric distortions – this includes barrel and pincushion distortion, along with more complex patterns.
  • Vignetting – Where the brightness of your image falls off towards the edges of the picture.
  • Blur or Lack of sharpness – This corrects some of the blurring introduced by your lens/camera combination. It does not extract detail where there was none, it just gets the best from what there is in the image.
  • Lateral Chromatic Aberrations. This is a where different colours focus at slightly different places on your image sensor, giving coloured fringes.

There is a lot of information on what is going on in the various parts of the software on the DxO site at I’ll not go into all the details here, but even something like vignetting is not as simple to fix as you might first think.

The software

Opening the program gives a basic file browser where you can see thumbnails of currently selected files. In the (annotated) example below are five files that I have dragged to the window to select them. The little tick marks next to the images mean that all necessary info is present to run the program.

File window showing files to be converted

To perform correction as well as raw conversion the program needs to know quite a bit of info about the original camera settings. My 1Ds for example does not save focussing distance in its EXIF data, so you have to enter it.

File is missing some infoSettings for raw file conversion and correction

The little question mark indicates that I need to enter missing info for this image.

Note that you do not have to apply corrections and can just do the raw conversion.

Some of the many options that you can adjust for conversion and correction.

This example is for the car image above, where there is no focus distance info supplied by the Canon 1Ds

White balance can be set to a number of presets or fine tuned as desired.

Of course you can always use the camera’s estimate.

Exposure compensation is available (+-4Ev) and the histogram is directly updated.

Distortion correction is adjustable from 0 to 100% (it is greyed out, since I have not yet entered a focusing distance)

Vignetting correction can also be varied from 0 to 100% and a second adjustment allows for it to be varied based upon image content (preserving highlights and preventing excessive shadow noise)

The output sharpening can be varied from soft to sharp, although examples in this review are all taken at the default setting.

The correction actions are the same type as shown in the earlier review, so I’ve not included them all again here. You do now have more control over the amount of correction applied and can preview the results.

The one example from the earlier tests I’ve included is the vent on the wall (1Ds, EF 16-35 2.8L at 16mm).

Original ImageHover Image

If you move your mouse over either image it will switch from the ACR to the DxO conversion (with correction)

Original ImageHover Image

The enlarged version (100%) is an unsharpened comparison between ACR and DxO — at their default settings.

The Photoshop histograms of the two files are shown below.

ACR histogram DxO histogram

The image below shows the effects of altering the sharpening setting from 0 to 2. Note that all the rest of the images in this review were converted using the default setting of 0. The default settings with ACR include some sharpening and colour noise reduction. Please consider this when comparing images.

As with all images in this review there is the basic problem of how to show subtle differences in images, on a web site, where I don’t know how you are viewing them, and any hope of accurate colour management is but a dream. I’d very much suggest you try your own comparisons.

Does it work?

The examples below show ACR and DxO conversions. Apart from shrinking and saving for web use, the full frame images have not been altered in contrast or levels. All crops are at 100% and unsharpened.


The problem of blown out highlights… (ACR and DxO versions)

Cape Kiwanda acr

Cape Kiwanda DxO

Cape Kiwanda, Oregon, USA

ACR Horrid conversion Much better DxO one
ACR really does have problems with sunsets! The JPEG from the camera does not show this weird posterisation. The DxO conversion is much happier handling blown out highlights. The image looks a little softer and is showing a bit of colour noise in the darker sea areas but ACR does by default apply some colour noise reduction and sharpening.

Lost in the shadows

To capture the delicate cloud patterns, much of the shot is quite underexposed. In applying adjustments later, this is just where the coloured band I mentioned in the ‘Moving to Digital’ article is likely to show up.

Dillon lake acr Dillon lake dxo

Dillon Lake, Colorado, USA

The coloured band - acr no band with dxo
The vertical stripe shows up when the image has a moderate bit of adjustment applied. The DxO version shows very little of the stripe, although some -slight- sharpening artefacts are visible along the skyline. There is also much less colour in the darker parts of the DxO image.Note that this is a 100% view, so the sharpening effects would be swamped when I applied the final sharpening before printing.

Difficult lighting at The ‘O Bar’ Leicester, UK

Mike in 'O' bar acr


Mike in 'O' bar dxo


At iso 1250 the bright saturated colours go awry in the ACR version. Note also the green posterisation around the light that occurs in the ACR conversion (just like in the sunset picture at the top of the page).

Noise at iso 1250

kebabs acr kebabs dxo

Late Night Food, Leicester, UK

Note the darker shadows in the DxO conversion

acr with cnr dxo with some noise acr without cnr
ACR at default settings, which includes some colour noise reduction and sharpening DxO has no colour noise reduction setting ACR as before, but with the colour noise reduction switched off

The neon signs are handled much better by DxO – and there is less noise.

acr neon dxo neon

The Sparkly bits…

spring acr spring dxo

Spring Green, Colorado ,USA

This is another effect mentioned in the ‘Moving to Digital’ article.

sparkles acr sparkles dxo
Lots of false colours around the brightest bits of water Still some colour, but not so pronounced

Off-axis detail

As well as raw conversion, the software can correct image distortions (shown in Pt1 and the earlier DxO review) This example was added to the original review after I had spent more time actually using the software, and revisiting some of my earlier work.

The image is of the Black Canyon of the Gunnison in Colorado. I was using the Canon 70-200 2.8 L image stabilised (IS) lens which is a superb lems that really brings out the capabilities of the 1Ds. The sample shots are 100% crops from the bottom right hand corner of the frame.


Although each shot is the corner of the frame, the coverage is slightly different where DxO has corrected for lens distortion

More ‘oomph’?

The next few examples show how the DxO conversions differ in overall ‘feel’

British Museum roof acr British Museum roof dxo

British Museum

chillis acrACR

chillis dxoDxO

Seattle market

'looking glass' acrACR

'looking glass' dxoDxO

The ‘Looking Glass’ bar, Leicester

beer acrACR

beer dxoDxO

Black and White?

If you’ve seen my work on the site, you will know I do quite a lot of B/W. I decided not to include examples here since conversion options and subsequent colour -> B/W processing is very dependant on the actual image and the effect I want to create. Some examples led me to the conclusion that using some DxO sharpening during conversion gave a noticeable improvement. I feel that the DxO route will give better results – certainly where there are blown highlights or specular reflection.

Is there a downside?

The inclusion of noise reduction settings in ACR is useful, although the slight colour noise in some of the DxO conversions would not be difficult to ‘fix’ in Photoshop, or with third party noise reduction plugins. The software is none too fast, taking just under 3 minutes to convert 5 raw files and nearly 6 minutes if full correction was included. This is on what is the fastest G5 Mac available – I’m told that the software does not currently support multiple processors. This is an area that really needs some attention. At the time of writing the Canon 1Ds MkII is not supported, but those 16.7MP files are going to hit that speed limit with a vengeance. For a real example, I recently shot some 70 different products for a small catalogue, assuming that I only had one picture of each to convert, that’s three quarters of an hour to convert them or one and a half hours to convert and correct.

The program is a stand alone one and does not need Photoshop to work with. This is not a problem for converting a few files, but if I’m using the file browser in Photoshop CS, it would be nice to have the option to send files to DxO for conversion. I often automate the processing of raw files after a job and although you can set options for handling lots of files in DxO it does not attempt to provide the batch handling facilities of Photoshop. Another feature of using ACR via the file browser is that conversion settings are remembered if you open the file again later.

I use ACR quite a lot and have thus compared DxO with it. I know of several professional photographers who regularly use Capture One and praise its workflow features for handling large numbers of pictures. It’s not cheap (C1 Pro is currently $450) but does an awful lot.

Another minor quibble is that the converted files are tagged with a resolution of 72dpi – ACR takes the default value from the EXIF data and with my 1Ds this is 240dpi. Not really a problem, but why 72dpi ? It’s also worth noting that you have to enter data that may be missing from the EXIF info — though not really the software writers fault if some manufacturers leave stuff out. For example, I take a lot of pictures with my 1Ds using matrix setting 4 (Adobe98), this info doesn’t come through, so I had to set the conversion options to use Adobe98.

Some people have questioned the pricing policy of charging more for support of ‘better’ cameras – seems OK to me – if I can afford a 1Ds and a stack of ‘L’ lenses then I’m obviously not on the same budget as a 300D buyer :-)

If your camera/lens combination is not supported then the software won’t work for you…
DxO Labs currently (11/04) offer Raw Engine support for Nikon D70, Canon EOS-1Ds, and Canon EOS-1DMK2. DxO Labs plan to offer Raw Engine support shortly for Nikon D2X, Canon 300D/Rebel, Canon EOS-10D, Canon EOS-20D, Canon EOS-1Ds-MK2.

Up to date [2015] details at


These results are limited to Keith’s tests with images from his 1Ds.

First thoughts are that the conversions with DxO have more ‘oomph’ and higher contrast, even without the corrections being applied. Add in the lens corrections and many images are appreciably better, particularly ones with more extremes of brightness. Colours seem more saturated, although this does seem to slightly emphasise colour noise in high iso shots.

The converted files also ‘fixed’ to a large extent some ‘problems’ I’d come across when using my 1Ds and mentioned in my article on moving to digital

  • Blown highlights (sunsets)
  • Colours with sparkly bits of water
  • A slight coloured band visible in some dark areas

If the software enables me to turn a good picture into a good print that I can sell, then a print sale pays for the software. I’d been working on one image for several hours, using multiple ACR conversions and lots of photoshop layers — it just didn’t work. The DxO conversion was better, even before I’d made any adjustments to the output file.

I can see a real use for this software for my landscape work, where I’m usually only working on a few images at a time, or some commercial jobs where the lens correction will produce much more accurate results. My work does not regularly produce the volumes of pictures that need immediate conversion and many of the features of a package like C1 Pro, but I do make use of the scripting support of ACR.

For image quality I’m well impressed with the software – it has more than lived up to what I expected after looking at the JPEG version. I’m not so happy about its speed on my Mac or ease of integration into a busy commercial workflow. This is a tool I’ll use for my best work, where a few extra minutes in creating the file is nothing to the hours I can spend working on some images. Well worth a look.

What would I like to see in future?

  • A version that works with Photoshop, maybe making use of file metadata to remember settings
  • Support for custom conversions such as Black and White
  • More speed :-)

There is a time limited demo available and I would recommend that you try it out on some of your own pictures.

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