--- John Whittingham <[EMAIL PROTECTED]> wrote:
> > Hmm. My calculator spreadsheet says that a 24x35mm frame
scanned
> > at 2438ppi nets an image 2304x3455 pixels in size, or 7.6
> > Mpixel. Something's off by a little bit somewhere... ;-)
>
> Never calculated it just reading from the manual, shouldn't
> that be 24mm x 36mm ?
Typo on my part, the spreadsheet is correct. If you got the
numbers from the scanner specification sheet, that's more
accurate as the scanner's maximum scannable area is likely not
exactly 24x36mm.
> > RAW is really the name of a format type, a "RAW file" means
a
> > different thing for every device that can create it. Vuescan
> > simply encode the metadata and sensor data into a very
simple
> > TIFF format. If you analyze a Pentax .PEF file, it also is
> > essentially a TIFF file with embedded metadata, a couple of
JPEG
> > low rez renders, and the sensor data in a tagged structure.
>
> Right, so a raw file might have any file extension (propriety)
> depending on the device that created it. When looking at the
files
> yesterday at work it was just (obviously) an exact scan of
the negative (when
> viewed with Photoshop CS) no rotation or anything. I tried
inverting to
> give me a positive and that gave me an image that would
require a lot of
> editing, I'm missing something...yes?
Vuescan's RAW has minimal metadata (he generates the processing
parameters by analyzing the scan data on the fly) and the sensor
data is basically just a row x column matrix of RGB pixel data
with linear gamma, that's typically what scanners produce as
straight output. Processing RAW output from B&W negative scans
means doing the inversion required and then adding the gamma
curve conversion to what our eyes like to see... relatively
simple to do. Processing RAW output from color positives is
somewhat trickier as color positives have a higher gamma than
negatives to begin with.
Processing color negatives to RGB positives ... well, you have
to invert it, remove the crossover mask per the particular
film's profile, then gamma correct it. I'll let Vuescan do that
for me. ;-)
Godfrey
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