RAW Converters Comparison

2. Defaults

In this RAW converters comparison this section’s goal is to establish exactly the default behaviour of the various converters. We will see whether lens profiles are applied, any sharpening or noise reduction takes place, and see some very different interpretations of auto white balance.

A RAW file starts out as a bunch of 1s and 0s representing a 2*2 Bayer colour filter matrix of 4 photosites – 2 green, 1 red and 1 blue. This has to be interpolated, or demosaiced, into a standard RGB image. The algorithm used for this process varies between RAW converters. Once converted into an RGB file the data requires further interpretation via camera profiles to tell the software what colours things should be in various lighting conditions. RAW converters will contain at least one profile for a camera, sometimes more than one, and you can usually create your own (not a simple and easy process unfortunately) and load that in too.

When a camera produces an image it embeds in that image information about the lighting conditions at the time; this is the white balance of the scene. If you shoot RAW then this is not baked into the file and the majority of people shooting landscape images will leave their camera set to ‘auto’ white balance. The camera usually gets this in the ballpark, especially in outdoor daylight conditions, and this can be fine tuned later in the RAW converter.

The default colours that a RAW converter produces are a combination of choices about the demosaicing algorithm, the camera profile the software applies, and the software’s interpretation of the information the camera has embedded in the file about the lighting conditions it recorded at the time.

As well as making these decisions some RAW converters go further when opening an image for the first time, and apply denoising and sharpening, and/or automatically correct lens defects, and practically all of them make exposure adjustments. The application of these modifications to the image is not always made explicit by the software.

The following image was taken with the Olympus E-M1 with the 12-40mm lens (at 40mm) at ISO 200 (base ISO for this camera), 1/1000s and f/5.6. It is slightly underexposed. I have chosen it because everybody has a fairly good idea of what colour grass, the sky and the sea should be (this colours in the image will change a little of course depending on how you have your monitor calibrated). [You can click on the images to bring up a larger version in a lightbox.]

The Conversions

 

The table below shows how each application interpreted the ‘auto’ white balance in the image, whether or not the lens has been corrected, whether or not noise reduction and sharpening was applied, and the resulting file size (these are 1576 * 1182 pixel files, i.e. double sized for retina displays, and have been produced by exporting a full size 16 bit uncompressed TIFF from each RAW converter and then using Photoshop’s Save for Web at 70% quality to output them).

App Kelvin Tint Lens NR Sharp Size
ALR 5350 +10 Yes Yes Yes 489k
AP 5733 21 Yes Yes? Yes 517k
C1P 5637 0 No Yes Yes 566k
CAP 4977 21 No Yes No 521k
DXO 5047 11 Yes Yes Yes 504k
ID 4980 14 Yes Yes Yes 565k
PN 5300 2 No Yes Yes 521k
RPP N/A N/A No No No 477k

Looking at the white balance of the images themselves it would be hard to say that any of them look particularly ‘bad’ or ‘wrong’. Our eyes and brains are easily fooled by slight differences in exposure levels that make images appear more or less saturated or cooler or warmer than in fact they are. The numbers in the kelvin and tint columns in the table are a little more informative (Raw Photo Processor supplies RGGB values). There is some considerable variation here and in the absence of very careful colour profiling and calibration it is impossible to make any judgement as to whether any of the software is ‘getting it right’. For the landscape photographer white balance is typically judged visually according to subjective preference, and in any case the image will often have its colours enhanced, or otherwise altered, in subsequent post processing.

The Olympus E-M1, like all micro four thirds cameras, supplies lens correction data to RAW converters in its EXIF files; there is no necessity to independently generate lens profiles as there is for almost every other camera. It is very easy to see whether these corrections have been applied here by scrolling through the images and looking at the truncated sheep on the left hand edge of the image. If the sheep gets further truncated then the lens correction profile is being applied. We will deal with lens correction in detail later in these articles but something to note here is that neither Lightroom or Aperture offer any way of disabling this automatic correction.

The final column containing the file sizes makes interesting reading, especially in conjunction with the noise reduction and sharpness columns. All other things being equal, file size is generally a very good indicator of how much detail is present in a file. A file with a large amount of high frequency detail, for example, an image of a beach where the individual sand grains are present, will be much larger than a file with an image comprised mainly of a blue sky. Here the image is the same, and unless significantly more detail is being revealed by the demosaicing algorithm used by each RAW converter, something else is going on.

What the file sizes reveal is that the image is being processed to a greater or lesser extent by the RAW converter at its default settings; most notably it indicates that sharpening and/or micro contrast adjustments are taking place. Sharpening and microcontrast adjustments introduce artefacts, artefacts that serve to (hopefully) make the image appear sharper and more detailed to our eyes, but these artefacts add to the file size. By contrast, denoising smooths over detail in files, and thus results in smaller file sizes, though this effect is outweighed by sharpening adjustments, especially in an image like this where very little noise is present to begin with.

Raw Photo Processor, where we can be reasonably sure from their documentation that nothing additional is being done to the image, has by far the lowest file size. Capture One Pro, where even a cursory examination of the image tells us that additional processing has been applied, has the biggest file size.

To clearly see what is going on with noise reduction and sharpening in these files they need to be viewed 1:1: [Note that clicking on an image will bring up an image in a new tab containing a matrix of the images, useful for comparing the conversions side by side, and essential for those with Retina screens who will be unable to see the details correctly in the images below.]

Comments

Lightroom has a notably small file size, considering that it is reducing colour noise only and is sharpening the file a little. It is applying its proprietary Adobe Standard color profile to the image, which looks OK with this image though, as we will see later in these articles, it can be improved upon. As noted, it automatically applies lens correction and this cannot be disabled.

Aperture‘s default noise reduction is a bit mysterious as we will see later, but it looks as if colour noise reduction is being applied, and we can see in its RAW Fine Tuning panel that some default sharpening is being applied, as is a contrast boost. This results in a medium file size and a default conversion that clearly has a little more contrast than some others. As noted, it automatically applies lens correction and this cannot be disabled.

Capture One Pro‘s rendition of the scene is clearly the most processed; it is darker, sharper and has greater contrast and saturation. It applies a custom ICC camera profile and also detects the lens correction data but does not apply it, which seems strange when its camera profile is so much punchier than anybody elses, and even more so because it actually applies some very heavy luminance noise reduction as well as colour noise reduction, and substantial sharpening, by default. Its documentation states that this is based on its profiling of the cameras but both settings are far too high in my opinion and yield results that are way too crunchy for default settings (we’ll come to this in more detail later). All this extra processing results in the largest file size.

Aftershot Pro applies RAW noise reduction, which appears to comprise a mixture of colour and luminance noise reduction, though the latter is more evident here, but no additional sharpening. This appears to borne out on examination of the image which appears softer than any of the other renditions but does leave one wondering why its file size is not smaller. The resulting image does not look very good.

DXO Optics Pro throws everything at the image with its sophisticated lens profiling, lens softness adjustments, which appears to involve deconvolution sharpening, and both luminance and colour noise reduction. No additional USM sharpening is applied which perhaps explains, in combination with the noise reduction, the relatively small file size.

Irident Developer has the second highest file size, just a shade under Capture One Pro’s, and this is accounted for by its lens adjustments, light colour denoising and sophisticated sharpening algorithms (which we will investigate later). Its colour rendition is quite flat and desaturated but this, arguably, gives a flat playing field for future colour enhancement with its powerful curve tools.

Photo Ninja‘s default rendition applies colour, but not luminance, noise reduction, colour profiling, contrast and exposure boosts (it is explicit about this), which combine to produce a very appealing image yet still with a medium file size.

Raw Photo Processor‘s default rendition is, in fact, not shown here as it is the only software not to provide exposure compensation out of the box. Following demosaicing the image is more than a stop darker than shown here and I have used its auto exposure compensation feature to the same level as the other conversions (an increase of 1.03 eV). With no noise reduction or sharpening the file size is, as noted, the smallest.

What this analysis of default renditions in our RAW Converters Comparison really reveals is differing philosophies about what should be initially supplied to the user. Photo Ninja, DXO Optics Pro and Capture One Pro supply something broadly equivalent to an out of camera jpeg (shot on default settings), albeit at much higher quality. They are images that could be used, at a push, without further editing. If I had to pick a winner here it would be Photo Ninja.

Lightroom, Aperture and Irident Developer choose to apply a little colour noise reduction and compensate for it with a little capture sharpening to give a starting point for further editing. They all do a good job of this but if I had to pick a winner it would be Irident Developer. Aftershot Pro appears to be attempting the same thing but the decision to apply some quite heavy noise removal and then not attempt to compensate for it is a strange one and it doesn’t make for an appealing default rendition.

Raw Photo Processor goes one step further, or perhaps that should be ‘less’, in providing a neutral editing base by doing almost nothing to the image. A solid starting point if you want to go to Photoshop and use specialist tools and/or plugins for further editing.

Having looked at the out of the box renditions in our RAW converters comparison we can now move on to look at their ability to render high frequency details.

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