Scanning automatic parameters - what do they do?

[vicmortelmans]

Filmscan 3600

I don't like machines that (pretend to) think for me. I've disabled the 'auto exposure' and 'auto gamma' on the scanner, but still some things are not clear.

The scanner settings allow to choose scanning pixel depth (8 or 16 bit) and scanning mode (normal/quality). Strangely, pixel depth nor scanning mode give me any different output image. I don't seem to get real grayscale as output either: it always generates RGB-images (24bit) with slight differences between the three channels.

What I would like is a real 16 bit grayscale output, but is that common in consumer-level filmscanners?

The scanning mode is a complete mystery. The manual says: "quality" mode may take somewhat longer and will give better... quality (yeah, right).

Another setting that you make is selecting film vendor and type. I wonder what this affects. Is it only because (talking b&w) different vendors have different base density and color cast? Or is also the actual image processed differently?

Still, I'm not fully satisfied in knowing what happens. I'd like to know about how negative densities relate to pixel values. (the scanner says 'measuring minimum density' when starting a scan, so it definitely knows about it!).

When you buy a roll of film or a developer agent, it usually comes with a sheet of paper that has some graphs on it, telling you the 'film characteristics', with min and max densities, influence of temperature and development time on gamma etc.... No such thing when you buy a (far more expensive) scanner! The only thing you get is a manual that says little more than "trust me, I know what I'm doing and you wouldn't understand anyway".

Groeten,
Vic

 

[amateriat]

In part, it depends on what you're using (scanning driver/plug-in/stand-alone application) to control the scanner. I have no idea what Microtek (which, I'm presuming, is the make of your scanner, although it looks an awful lot like a certain Pacific Image model) bundles with their scanners to control them with, but from your description is sounds awfully simplistic. Is there an "advanced" mode for the driver which you might have overlooked? That mode, if it exists, might give you more specific control parameters to work in. A good driver will offer specific control over matters like DPI/PPI and others.

Bit depth: the difference here isn't one you'd see on-screen (or, necessarily, in a given print). The difference shows up when you start working the scanned image in Photoshop or any other image editor: working with a 16-bit image is simply less destructive to the file (and you're "destroying" image data each time you mess with it, which is also why lots of people prefer to work with layers) than it is working in 8-bit. When you're finally done with your assorted tweakings on a given file, you can save a working copy of it as an 8-bit file for printing (some believe that, for b/w work anyway, that a print from a 16-bit file is superior to an 8-bit file; I'm somewhat agnostic on this). Save the original file unchanged, in case you have second thoughts down the line – it beats having to re-scan.

One hot tip: try VueScan. IMO, it's among the best stand-alone scanning apps available, and clearly the most cost-effective as well, offering an amazing degree of control over scanning parameters – perhaps a bit too much, as it might seem at first glance. A bit of a learning curve, but absolutely worth the effort. Think of it as a crisp six-speed manual transmission option to the automatic you're currently driving. 🙂


- Barrett