The fix is in: We test Sigma’s dp2 Quattro firmware and Photo Pro software updates

by Dave Etchells

posted Monday, September 8, 2014 at 9:40 AM EDT


As we noted in our recent Firmware Friday roundup, Sigma has updated the firmware for their dp2 Quattro camera, as well as the associated Sigma Photo Pro software, addressing among other things a couple of image quality issues that surfaced in our testing. All Sigma dp2 Quattro owners will want to download and install the new software and firmware.

The Sigma dp2 Quattro has really turned heads -- ours included -- with its amazing resolution and optical quality in a sub-$1,000 package. We had the privilege of releasing some of the first test shots taken with it, and our readers have responded with enormous interest.

We've been holding off on posting a Shooter's Report or further analysis of the camera, though, waiting for firmware updates to address a couple of issues we discovered in our testing. We're happy to report that those updates have now been released, with the results shown in the crops and linked files below.

The first issue was noted and commented on by many readers: The dp2 Quattro's in-camera JPEG processing lost almost all detail in the always-troublesome red fabric swatch in our Still Life test. While it's common for cameras to have difficulty separating detail from noise in this particular subject, the dp2 Quattro lost virtually all detail, even at its base sensitivity. Interestingly, though, Sigma Photo Pro (Sigma's raw processing software for the camera) produced an excellent rendition of the problematic swatch.

It turns out that the poor in-camera rendering of the red swatch was the result of a bug in the dp2 Quattro's noise-reduction processing, which Sigma discovered as a result of the poor showing in our tests. We had understood that firmware version 1.0.1 addressed this problem, but we weren't able to test it until earlier this week, as our review sample was out with senior writer Eamon Hickey. Now that version 1.0.2 is out, it looks like the red-handling issue was either corrected or further corrected in this most recent version, and we've re-shot our Still Life test images using it.

As it happened, Eamon encountered another issue in his shooting, that turned out also to be present in one of our early real-world shots from the camera. This second problem took the form of pastel magenta and green tints appearing in neutral-toned areas that also had significant luminance texture. Eamon found this only in images processed through SPP, but when we looked at one of our original gallery shots taken with the dp2 Quattro, we saw it in both in-camera JPEGs (at least, those shot in Landscape color mode), as as well as in the Sigma Photo Pro outputs.

As far as we can tell, the just-released firmware version 1.0.2 and Sigma Photo Pro version 6.0.6 address this second issue with pretty good success, although there are still hints of it to be found in our original gallery shot when processed through SPP 6.0.6.

The crops below show before-and-after versions of images affected by the two issues mentioned above, so you can judge for yourself the success of the solutions. Full-resolution files either straight from the camera or processed through SPP with default settings are a click away, so you can inspect the originals yourself. X3F-format raw files are also available, via links on the Sigma dp2 Quattro thumbnails page.

Issue 1: Detail in highly-saturated red hues

As mentioned above, in-camera JPEGs of our Still Life target showed a severe loss of detail in the red fabric swatch, which seems to cause problems for so many cameras. Curiously, though SPP did an excellent job. In the table below, the first pair of images were shot at ISO 100 with the original v1.0 firmware, and the one on the right processed in the the corresponding version of Sigma Photo Pro, v6.0.4. The second pair were shot with v1.0.2 firmware and processed in the new Sigma Photo Pro v6.0.6.

Sigma dp2 Quattro Firmware Update Comparison
Detail handling in saturated reds

Firmware v1.0, In-Camera JPEG
Firmware v1.0 image, converted in SPP v6.0.5
sigma dp2 quattro image sample orignal firmware
sigma dp2 quattro sample image, converted in spp v6.0.4
The Quattro's original v1.0 firmware had a lot of trouble with our infamous red swatch, losing nearly all detail. On the other hand, Sigma Photo Pro version 6.0.5 did an excellent job.
Firmware v1.0.2, In-Camera JPEG
Firmware v1.0.2 image, converted in SPP v6.0.6
sigma dp2 quattro test image, firmware v1.0.2
sigma dp2 test image, converted in spp v6.0.6

Sigma's firmware update version 1.0.1 was designed specifically to quash the noise-reduction bug that caused the poor red-swatch performance in our Still Life test images.

The crop above left was captured with firmware v1.0.2, which carried that fix forward. The result is still far from perfect, but is a significant improvement over the original. The crop on the right was processed from the RAW file captured at the same time as the in-camera JPEG on the left, using Sigma Photo Pro version 6.0.6.

Again, the result is greatly superior detail, even improving contrast in the red swatches a bit over 6.0.5. While the dp2 Quattro's in-camera JPEGs are generally very good, being amazingly crisp and detailed for in-camera images, Sigma's SPP software is clearly the way to go to extract the full image quality that the Foveon sensor technology is capable of delivering. It does require a fast computer and some patience, though -- we'll report more on that in our full review.

Issue 2: Magenta/green tints in textured neutral tones

The second issue we encountered was a bit more subtle. Textured areas with relatively neutral tones showed some soft magenta/green color artifacts not present in the original subject. The errant tints covered varying amounts of area, but seemed generally to appear in areas where there was some texture to the neutral-toned subject matter. We inadvertently shot the original subject below with the camera set to "Landscape" mode, which boosts color saturation and contrast a little, and seemed to emphasize the false colors. Converting to JPEG with Sigma Photo Pro version 6.0.5 in "Standard" mode reduced the prominence of the color artifacts slightly, but perhaps only in proportion to the overall reduction in saturation and contrast. SPP 6.0.5 seems to largely eliminate the problem in the Standard color setting, although Landscape mode seems to leave it more or less as it was.

This shot was captured with the original version 1.0 firmware, with the camera (accidentally) set to Landscape mode. The image above is a 600-pixel version of the original, in-camera JPEG.

The crop above is from the same in-camera JPEG as shown at the top. If you look closely, you can see some magenta and green colors in the hair of the cat's nose that weren't present in the subject.

This crop is from a JPEG exported from the original .X3F raw file using Sigma Photo Pro version 6.0.5, with the color mode set to Standard, rather than Landscape. The green/magenta false color is slightly reduced over that seen in Landscape mode (which produced results nearly identical to the in-camera JPEG), but the difference seems mainly to be down to the slightly lower contrast and color saturation overall.
Working from the same original raw file, the latest Sigma Photo Pro version 6.0.6 largely corrects the false-color issue when the Standard color setting is used. There's still a hint of it there if you know where to look, but to all intents and purposes it's gone.

Overall, firmware 1.0.2 and Sigma Photo Pro version 6.0.6 do a pretty good job of addressing the two issues we found. The in-camera JPEG processing still has some trouble with the red swatch that plagues so many cameras, but the results are much improved over firmware version 1.0. Sigma Photo Pro v6.0.6 seems to do a pretty good job of addressing the problem of magenta/green false color in textured neutrals, as well, at least in situations where we found it to be an issue previously.

Of course, both updates bring other benefits too. This latest firmware also improves autofocus accuracy with low-brightness/contrast images, and adds an option to select whether the viewfinder image previews the exposure level or not. The newest Sigma Photo Pro version also addresses a couple of other bugs, and from what we can see, improves both detail rendition and low-ISO noise reduction as well. Both are clearly worthwhile updates for Sigma dp2 Quattro users.