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Thread: "Brightening" of processed Ektachromes

  1. #11

    "Brightening" of processed Ektachromes

    Pete Andrews wrote:

    > Most scanners could, in fact, see a higher density, simply by winding up the intensity of the lamp

    This is untrue for most scanners, unless you're willing to allow the CCD's analog output to saturate in mid- and light-tones. If you turn up the lamp, then you'll simply end up shortening the integration time (the amount of time between transfer gate signals) to stay under saturation. Provided that the integration time was reasonably short to begin with, this puts you right back where you started in terms of maximum density.

  2. #12

    "Brightening" of processed Ektachromes

    What I said about 'turning up the wick' is absolutely true Patrick. I didn't say it would increase the dynamic range, or that it wouldn't have any other deleterious effect. In fact, I went on to say that it wasn't that simple.Why do you assume that I was only referring to CCD scanners? PM based drum scanners don't saturate easily, and some of them actually use lamp intensity to control exposure.

    Paul, the bit-depth of a scanner is more important for maintaining a linear relationship between density/brightness and the digital output, than in capturing more colours. Greater bit depth should also allow more flexibility in mapping the tone curve to an 8 bit output, but if the scanner is CCD based then the limitation is probably with the sensors, rather than the rest of the circuitry. Most CCDs have a dynamic range of 4 or 5 thousand to 1, about 3.6D in terms of density, or 12 bits in digital terms. Feeding this into a 16 bit A/D won't improve this basic limitation, and that's why your high-end flatbed still can't beat your mid-range drum scanner.The real bottleneck these days is that damned 8 bit per channel output. I think if we can make 16 bit the norm, then desktop scanner makers will be prodded into doing some catching up.Anyway this is all way off topic. Sorry!

  3. #13

    "Brightening" of processed Ektachromes

    "I think if we can make 16 bit the norm, then desktop scanner makers will be pro dded into doing some catching up." Pete, not long ago, this would have seemed a ridiculous expense of megabytes. Bu t now, with the super-computers being brought to the desktop at a low price, new huge and cheap harddisks (Ultra ATA 66+) and affordable memory, this norm, already partly supported by Photoshop and some scanners is at hand. S till, output machines and monitors have to be updated.

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