Raw and Raw Conversion

Supplied software

The SD1 is provided with Sigma Photo Pro (v5.2.1 at the time of writing) for developing its X3F raw files. Indeed for more than perhaps any other camera, SPP becomes a fundamental part of the overall experience of using the SD1. If you want to get the best out of the camera, you really need to shoot Raw, and to process Raw you really have to use SPP - there's not really another sensible option.

Sigma Photo Pro is like the camera in more ways than one - it's slow, quirky, and missing some standard features we've come to take for granted in Raw processors. But, again like the SD1, if you're prepared to take the time to work it out and play to its strengths, then it's capable of excellent output. But you'll have to be very patient - did we mention it's slow?

SPP has a number of impressive features - the 'X3 Fill Light' for dealing with high contrast scenes works particularly well, and the ability to display clipping on a per-channel basis is useful - but at the other end of the spectrum is is completely missing such basic functions as straightening or crop tools. There's also no means of correcting for lens aberrations, despite the camera only accepting Sigma's own lenses (for which the company even supplies correction profiles to Adobe). The upshot is that, if you're after the very best results - and there's little point in buying the SD1 if you're not - you'll probably need to export every image to Photoshop for fine-tuning. Needless to say, this is a tedious way of working if you regularly have lots to shots to deal with from a single session.

Sigma Photo Pro is in essence a very simple program. In the main window you can navigate through folders, and display thumbnails of your files. You can also call up the essential capture information for each image.
The main toolbar offers some very basic viewing and file management options; SPP will recognise images that have been protected or marked in-camera.
Double-clicking a thumbnail will open a 'Review' window, in which you can make changes and fine-tune your raw conversion Highlight- and shadow-clipping warnings can be displayed in red and blue, unusually (and usefully) on a channel-specific basis. The values at which these will be displayed are also user-customisable.
'X3 Fill Light' has long been one of SPP's most useful tools for control of tonality.

New to v5.2 is the 'Highlight Correction' option, which can improve the appearance of highlights that would otherwise be clipped to pure white.
This shows the effect of the 'Highlight Correction' slider on clipped out-of-focus highlights. In the example on the left it's set to 'Restore', on the right to 'Neutralize'. It's subtle, but can be genuinely effective.

Once you've got the hang of what all of the sliders do, and how they interact, then you'll start to find that the image quality you can get out of the SD1's files using SPP can be spectacular. The software makes it remarkably easy to produce balanced images from scenes with high dynamic range, for example, by offsetting negative Exposure (to recover highlights) against Fill Light (to maintain shadow detail). You can finally tweak your tonality using the shadow and highlight sliders.

The big problem with SPP is its speed - it's very slow at rendering and updating preview images, and you're perpetually left feeling that the SD1's files contain too much data for it to handle comfortably. This is compounded by the fact that it's unable to process raw data in the background, or multitask in any meaningful way. One (minor) saving grace is that you can set up all your adjustments image-by-image, then leave the computer to batch-process its way through them while you have a cup of tea (or more likely a three-course dinner), but to be honest this sort of behaviour is years out of date.

When you first open an X3F file, SPP will initially display a preview based on the embedded JPEG, but you then have to wait several seconds for it to render a genuine preview of what you'll actually get, as the output is distinctly different from the camera's JPEGs. Basic tonal adjustments are previewed in real time, but if you choose a different colour mode or white balance then you have to wait for an updated preview to render all over again. Most frustratingly, to check fine detail you have to click the 'Full Res' button on the toolbar (SPP isn't intelligent enough to do this automatically in the background), then wait for what seems an eternity as the software processes the image just so you can examine it at 100%.

When you first open Raw a file for editing in SPP, it first displays the embedded JPEG; you have to wait a few seconds for it to render a preview of the raw conversion. At high ISOs in particular the two can look very different; this is ISO 6400.

Similar problems occur when you're trying to determine the best noise reduction settings. Normally this is best achieved by viewing the image at 100% magnification, adjusting sliders and deciding which combination looks best for your intended use. But SPP won't update its 100% view if you change the NR settings; it snaps back to full screen mode instead.

Overall Sigma Photo Pro's workflow leaves a lot to be desired; indeed it feels like it comes from a time before the concept was even invented. While the results can be excellent - indeed it's difficult to overstate just how good the SD1 + SPP combination can be at its best - we're not entirely convinced they're worth so much pain.

Raw conversion

Normally we like to compare the supplied Raw conversion software with commonly-used third party Raw converters, most notably Adobe Camera Raw. However Raw support for the SD1 is currently limited to just Sigma Photo Pro, so for the moment that's all we can look at.

  • JPEG - Large/Fine (default settings)
  • SPP - Sigma Photo Pro (default settings)

Sharpness and Detail

At default settings and low ISO, the output from Sigma Photo Pro is quite similar to the camera's JPEGs, both in terms of detail rendition and (rather muted) colour palette. It's not identical though; most obviously shadow contrast is a bit higher, which makes images look a little less flat. But crucially, both JPEG and Raw offer exceptional rendition of dine detail.

JPEG (Default settings, manual WB)
ISO 100 studio scene 100% crop
Sigma Photo Pro, (Default settings, manual WB)
ISO 100 studio scene 100% crop


The out-of-camera JPEG and Raw file converted using SPP give essentially identical results in our resolution chart test. Because the Foveon sensor does not use an optical low-pass filter, the SD1 continues to resolve the lines of our test chart beyond the point that a conventional Bayer sensor of similar pixels count would blur the lines together. Inevitably it also shows aliasing and false detail beyond the sensor's Nyquist frequency (3136 lph); while this is technically a flaw, in practice it tends to give an impression of detail and texture that rarely detracts from real-world images. The Foveon design also means that the SD1 is immune to the colour aliasing we often see in these shots.

JPEG from camera Sigma Photo Pro (Raw)