photoblogography - Just some stuff about photography

Canoscan 9000F vs Minolta DSMP

a bit of pixel-peeping

in Film , Monday, July 12, 2010

I’ve recently started using a Canon Canoscan 9000F to speed up my scanning workflow, using it primarily to make fast, low resolution quick’n’dirty index scans. I’ll write more about that in another post, but I thought it would be interesting to see how the Canoscan stacks up against the Minolta Dimage Scan Multi Pro in the overall image quality stakes. I should emphasise at the outset that I do not expect a $350 flatbed scanner to match a $3500 film scanner, but you never know - and since the film scanner is no spring chicken, I have to start thinking about what I’m going to do when the day comes that it stops working.

Comparing scanners can be fraught with peril, as my colleague Bruce Percy discovered not so long ago, but I’m going to leap in regardless.

So, I took a recent a Velvia 100 XPan shot of a local cow I happened to pass by the other day, I scanned it on both scanners, in both cases using SilverFast AI Studio, both with Auto-IT8 calibration, and to 48-bit HDR Color with Digital ICE enabled on the Minolta, and 64-bit HDRi on the Canoscan (Silverfast does not yet support HDRi on the Minolta).  In both cases I used Silverfast’s Multiexposure, and scanned at 4800dpi. This is the optical resolution of the Minolta; the Canoscan claims 9600dpi, which seems ... unrealistic ... and in any case, various authorities claim that 3200 dpi is as much as you can extract from 35mm film. However, in my experience, the Minolta does deliver a little more data at 4800. I also used the Scanhancer on the Minolta, to get the best possible result.

I made the scans,then opened both in Silverfast HDR Studio. Here, for the sake of a level playing field, I used the Auto function to adjust tonal balance, and output to ProPhoto RGB colour space.

I was interested in three factors: dynamic range, colour fidelity, and detail. The first thing I looked at were the histograms from the two scanners. First Canon, then Minolta:

hist canon.jpg

Histogram from the Canon scan

hist minolta.jpg

Histogram from the Minolta scan

It is fairly evident from these that the Minolta scan holds a greater range of data values. There is also an interesting offset in the bright peak in the blue channel in the Canon’s histogram.

So, now to the colour comparison - and introducing the aforementioned cow: first the Canoscan, then the Minolta



Well, we’re not too far out. The blue peak in the Canon histogram shows itself in the blue tint to the sky, which arguably is more attractive, however, and you’re going to have to take my word for this, the Minolta version is pretty much spot on compared to the Velvia transparency.

I’m not entirely sure what is going on here, as I would expect the Auto-IT8 calibration to smooth this out. However, I’m not sure that using a 35mm IT8 target on the Canoscan is ideal (I need to check with Lasersoft), and of course this is just one image ... hardly a trend!

Of course I’m not too concerned about this: the Minolta is my reference scanner, and the scans that Silverfast delivers from that are extremely accurate. However, my general and possibly naive assumption is that while dynamic range and resolution will of course vary, in a fully calibrated system, and within device limits, the colour gradation should be quite close.

The last thing to look at is detail. In both cases I applied light “capture” sharpening using PixelGenius Sharpener (in future I may evaluate using Silverfast USM sharpening for this step). Below are 100% crops from each scanner, Canoscan first. Please do note that JPEG compression does degrade things a little.


Here the difference is quite clear. From other experiments I’ve observed that the Canoscan’s effective optical resolution peaks at around 2400dpi - there is no difference in scan quality at higher resolutions. The Minolta is resolving grain (what little there is in Velvia 100) and this has been slightly accentuated by the light sharpening.

In terms of usable detail, however, there’s not a lot in it, and both will print fine up to A3. What is more important is that the Minolta resolves considerably more shadow detail. I suspect that the Canon is losing out by not having any control over focus. In fact here I let the Minolta auto-focus, but for critical cases, I often use manual focus, which can make quite a difference (it’s a very slow process though). Here, actually, I thing the AF has done a pretty good job.

So, my conclusion is that the Canoscan delivers a very commendable performance, especially considering the price. I’m a bit intrigued by the inaccuracies in the colour gradation, and I’ll probably investigate that a little further when I have time - but I don’t consider it a big deal.



Silverfast DC-Pro for E-1 RAW

in Olympus E-System , Monday, February 07, 2005

Lasersoft Imaging is a company with an impressive pedigree in digital imaging. For years, their Silverfast software has been the gold standard in scanning software, supporting a huge range of scanners with a sometimes bewildering variety of options and configurations. From low end consumer devices to high end drum scanners, Silverfast has it covered. Many hardware providers have given up on their software, and either bundle just Silverfast or provide alongside a token face-saving effort of their own. Silverfast is extremely powerful and with some experience can be used to extract the best from scanners, especially film scanners. However, it isn't exactly a usability paragon (although it is better than its only serious rival, the cranky and bug-ridden Vuescan). Since Silverfast is basically a generic image enhancement application layered on top of a device driver, it didn't take a huge leap of imagination to work out that the device driver could be a RAW decoder. And hence a new range of Siverfast variants, the DC range aimed at digital cameras. As a long-time Silverfast Ai user, since Lasersoft claim to support the E-1, I've been tempted to try it for some time. There are 4 variants to Silverfast DC - DC-SE, DC-VLT, DC Pro, and DC Pro Studio. DC SE is the basic version, bundled with some cameras (e.g Leica Digilux); DC-VLT includes the VLT (Virtual Light Table), a RAW engine limited to 24 bit output, and the full, sometimes overwhelming set of image adjustment utilities. DC Pro is the same (also includes VLT) but supports 48 bit output. DC Pro Studio adds some extra features to DC Pro, for example the clone tool, which is I think unique in RAW converters, allowing dust and hot pixels to be removed at the conversion stage. Confused ? Well we've hardly started on Lasersoft's Byzantine product segmentation! Anyway, the main thing to remember is that we have effectively two loosely coupled applications. VLT is essentially for selecting, organising and managing digital images, DC is for processing them, although the boundaries are a bit blurred. The functionality of the VLT depends to some extent on the version. You switch between the two but you cannot have both on screen at the same time. The reason for this is, I suspect, a legacy issue, as the DC series are really a bolt-on to the Ai scanner series. However, the VLT isn't bad at all, once you get used to it. It is fast and responsive, highly customisable, and in my opinion better than Photoshop's File Browser. You can use VLT to select photos from the file system and sort them into any number virtual albums, you can queue images for background processing, and a host of other things, but it must be said that certain features, such as batch processing, are as clear as mud. In many ways VLT combines the best of Olympus, PhaseOne and Adobe's features, but one thing missing is the ability to compare several previews at once. It does avoid imposing its own idea of the world, unlike C1 with its annoying sessions concept. The only drawback is, as I said before, the fact that you have to switch to another application to apply corrections. VLT has also a very complete EXIF browser, one of the best I've seen. vlt.jpg
Silverfast's Virtual Light Table Unfortunately it is when you switch to the (confusingly named) "Silverfast" application that the early promise starts to fade. The initial images presented look quite strange, apparently because Silverfast doesn't use the in-camera white balance. Bringing up the same image simultaneously in Olympus Studio 1.2, C1 SE v3.6 and Silverfast gives almost identical results in the first two, and a completely different rendition in Silverfast. Silverfast does seem to bring out better shadow detail than the other two, but at the expense of a bizarre colour balance which is all but irretrievable, even with the fast power of the image correction tools on offer. DC-Pro, unlike DC-VLT, appears to use the Olympus RAW internal thumbnails (with DC-VLT, thumbnails are generated by VLT, like in C1). Ironically, when you first open an image in Silverfast DC Pro, a very nice looking preview - generated from the thumbnail, I assume - flashes up, only to be overwritten by the above-mentioned oddity. dcpro.jpg
The Silverfast image adjustment application A core feature of the generic Silverfast range is color managed workflow. Silverfast allows you to - indeed encourages you to - calibrate your scanner against a supplied target. DC-Pro also includes camera calibration features, and a supplied target. This really would be a winning feature, except for the fact that even Lasersoft themselves point out that camera calibration is so dependent on external factors that it is of little use except in controlled shooting conditions. It is an interesting feature to have, but it may be at the root of the problem which Silverfast has with the E-1: the interpretation of the RAW data is based on camera profiling, and it appears that with the E-1 at least, Lasersoft have got this seriously wrong. The adjustment tools do allow a reasonable rescue operation to be mounted, but this requires first going to another application to read the in-camera white balance, and to generate a reference image to try to match. All a bit pointless really. For those unfamiliar with the scanner versions, Silverfast also includes some strange-seeming options, such as a Descreen filter. Very useful for scanning printed paper, but not much called for in RAW processing. In the same menu as this unlikely option are the sharpening (USM) tools, and another hangover from film scanning, the GANE grain reduction tool (which can't be applied at the same time as USM!). This, at least, can be used for noise reduction - except that there is a noise reduction slider in the Picture Settings widget (which only comes with DC Pro Studio, as far as I know - even more confused ?). All this needs a serious tidying up operation. DC-Pro Studio adds yet more mayhem, with a more flexible sharpening tool, the above mentioned clone tool (which actually includes a texture matching option putting it on a par with Photoshop's healing brush), and the AACO Auto Adaptive Contrast Optimisation tool, "for the correction of dark, high-contrast areas of the image while preserving the details in the highlights". AACO is a newcomer to Silverfast's vast acronym collection. It seems quite useful, but the early version in Ai Studio was buggy. A final point is that it isn't quite so clear where in the processing these tools are applied. Mac and PC trial versions of all DC Pro variants are available from Lasersoft. The trial is fully functional but imposes a watermark on final output. It does allow one very positive point to be seen - apparently Lasersoft have managed to avoid the dreaded "tetris effect" in bright reds which plagued earlier versions of C1 and others. dcpro2.jpg
300% zoom in Photoshop of Silverfast converted RAW - no Tetris! Silverfast is especially interesting because it offers the promise of a one-stop, integrated solution for both digital and film-sourced raw image processing. It is competitively priced compared to alternatives such as C1, and unlike any other rival it matches and sometimes goes beyond Olympus Studio's organising features. The Silverfast correction tools are really all-encompassing, and in some areas, for example the ability to simultaneously adjust individual RGB or CMY channels, way ahead of Photoshop. A free rotate tool similar to C1's would really complete the package. However the transition from scan correction to RAW adjustment software has been handled clumsily, and needs a serios rethink. There are far too many ambiguous, redundant or plain irrelevant featires. But for Olympus E-1 owners, at present colour fidelity is a showstopper. Lasersoft have stated on the Silverfast forum that fixing the GUI is a priority. If they can fix a few other things, improve E-1 profiling, and try to separate out specific film scanning features from specific digital RAW adjustment features, then they may still be well worth watching.

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