Vuescan: my new advanced workflow

Discussion in 'Scanners' started by Alan Smithee, Jul 6, 2005.

  1. Alan Smithee

    Alan Smithee Guest

    I've been busting my brain trying to make Vuescan do what I want it to do.
    Using the specified "advanced workflow" consistently produces muddy shadows
    and never enough room on the toe of the curve. My new advanced workflow is
    as follows: Preview, Lock Exposure at 1.0 (ie. ignore whatever value the
    program comes up with), do a preview, lock image colors, presto plenty of
    toe room for playing with in Photoshop's levels control. The only noticable
    effect is that the Film Base values all seem to creep up a little. Anyone
    else find Vuescan works best this way?
     
    Alan Smithee, Jul 6, 2005
    #1
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  2. Alan Smithee

    Erik Krause Guest

    Im Posting von Alan Smithee <> stand:

    > I've been busting my brain trying to make Vuescan do what I want it to do.
    > Using the specified "advanced workflow" consistently produces muddy shadows
    > and never enough room on the toe of the curve. My new advanced workflow is
    > as follows: Preview, Lock Exposure at 1.0 (ie. ignore whatever value the
    > program comes up with), do a preview, lock image colors, presto plenty of
    > toe room for playing with in Photoshop's levels control. The only noticable
    > effect is that the Film Base values all seem to creep up a little. Anyone
    > else find Vuescan works best this way?


    This depends largely on the used scanner. If exposure 1.0 is enough to
    have the scanner look into the densest parts it will work. Most likely
    it will not work for dense slides, but for C41 material, which has a
    far lower density, it should, at least if the scanners standard
    exposure is near to the optimum one.

    For C41 I have another super-advanced workflow only applicable to Nikon
    scanners: Do normal advanced workflow, then in color tab look at the
    film base color values. Take the largest one and divide by the next
    one. Take the result as a multiplier for the corresponding channel
    analog gain value. Do the same for the remaining channel.

    If f.e. your channels have film base color values: Red 0.9, Green 0.6
    and Blue 0.5 the resulting analog gain values will be Red 1.0, Green
    1.5 and Blue 1.8. Unlock film base color, do another preview and lock
    again. The film base color values on color tab should be all more or
    less the same. If they differ you can repeat the steps.

    This way you get a pretty neutral negative. Now you can increase all
    (locked) film base color values to 1.0 and scan the whole roll of film
    with these settings. In my experience this neutralization of film base
    color by different channel exposure works much better than the
    mathematical one and you get almost clipping-free image data.

    --
    Erik Krause
    Digital contrast problems: http://www.erik-krause.de/contrast
     
    Erik Krause, Jul 6, 2005
    #2
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  3. Alan Smithee

    Alan Smithee Guest

    Erik Krause wrote:
    > Im Posting von Alan Smithee <> stand:
    >
    >> I've been busting my brain trying to make Vuescan do what I want it
    >> to do. Using the specified "advanced workflow" consistently produces
    >> muddy shadows and never enough room on the toe of the curve. My new
    >> advanced workflow is as follows: Preview, Lock Exposure at 1.0 (ie.
    >> ignore whatever value the program comes up with), do a preview, lock
    >> image colors, presto plenty of toe room for playing with in
    >> Photoshop's levels control. The only noticable effect is that the
    >> Film Base values all seem to creep up a little. Anyone else find
    >> Vuescan works best this way?

    >
    > This depends largely on the used scanner. If exposure 1.0 is enough to
    > have the scanner look into the densest parts it will work. Most likely
    > it will not work for dense slides, but for C41 material, which has a
    > far lower density, it should, at least if the scanners standard
    > exposure is near to the optimum one.
    >
    > For C41 I have another super-advanced workflow only applicable to
    > Nikon scanners: Do normal advanced workflow, then in color tab look
    > at the film base color values. Take the largest one and divide by the
    > next one. Take the result as a multiplier for the corresponding
    > channel analog gain value. Do the same for the remaining channel.
    >
    > If f.e. your channels have film base color values: Red 0.9, Green 0.6
    > and Blue 0.5 the resulting analog gain values will be Red 1.0, Green
    > 1.5 and Blue 1.8. Unlock film base color, do another preview and lock
    > again. The film base color values on color tab should be all more or
    > less the same. If they differ you can repeat the steps.
    >
    > This way you get a pretty neutral negative. Now you can increase all
    > (locked) film base color values to 1.0 and scan the whole roll of film
    > with these settings. In my experience this neutralization of film base
    > color by different channel exposure works much better than the
    > mathematical one and you get almost clipping-free image data.


    Very interesting. I'm going to try this. So to repeat what you've already
    said.
    1) go though the Advanced Workflow.
    2) Divide Red base/Green base= 1.5, Divide Red base/Blue base = 1.8, which
    yields working values of R=1.0 G=1.5, B=1.8
    3) Unlock Film Base Color, Preview, Lock Film Base Color again.

    What's going on with the RGB Exposure during all this?
     
    Alan Smithee, Jul 6, 2005
    #3
  4. "Alan Smithee" <> wrote in message
    news:ElYye.1875764$Xk.596605@pd7tw3no...
    SNIP
    > What's going on with the RGB Exposure during all this?


    The ratio of R, G, and B exposures is preset by VueScan when scanning
    color negatives, and differs between scanner models. On Nikon Scanners
    the ratio can be changed by the user. These ratios are supposed to
    neutralize the color of the film mask.

    Bart
     
    Bart van der Wolf, Jul 7, 2005
    #4
  5. Alan Smithee

    Alan Smithee Guest

    Bart van der Wolf wrote:
    > "Alan Smithee" <> wrote in message
    > news:ElYye.1875764$Xk.596605@pd7tw3no...
    > SNIP
    >> What's going on with the RGB Exposure during all this?

    >
    > The ratio of R, G, and B exposures is preset by VueScan when scanning
    > color negatives, and differs between scanner models. On Nikon Scanners
    > the ratio can be changed by the user. These ratios are supposed to
    > neutralize the color of the film mask.
    >
    > Bart


    Good to hear from you Bart. I have an Epson 3200. I just see one RGB value
    on my input tab, do Nikon scanners show three where I see one? What exactly
    is the film base setting(s) doing? Does it adjust gamma or is it changing
    the exposure ratio for each channel? In later releases of Vuescan I can now
    choose to scan using just one color channel, doesn't this effectively give
    me the ability to change the RGB ratio?
     
    Alan Smithee, Jul 7, 2005
    #5
  6. Alan Smithee

    Erik Krause Guest

    Alan Smithee <> wrote:

    > I have an Epson 3200. I just see one RGB value
    > on my input tab, do Nikon scanners show three where I see one?


    Yes. They are called 'analog gain' but they simply are a channel
    specific exposure multiplier.

    > What exactly
    > is the film base setting(s) doing? Does it adjust gamma or is it changing
    > the exposure ratio for each channel?


    None of that. It simply is subtracted from the pixel values.

    > In later releases of Vuescan I can now
    > choose to scan using just one color channel, doesn't this effectively give
    > me the ability to change the RGB ratio?


    Can't say anything about that, since I don't own an epson scanner...

    --
    Erik Krause
    Digital contrast problems: http://www.erik-krause.de/contrast
     
    Erik Krause, Jul 7, 2005
    #6
  7. Alan Smithee

    Erik Krause Guest

    Alan Smithee <> wrote:

    > > This way you get a pretty neutral negative. Now you can increase all
    > > (locked) film base color values to 1.0 and scan the whole roll of film
    > > with these settings. In my experience this neutralization of film base
    > > color by different channel exposure works much better than the
    > > mathematical one and you get almost clipping-free image data.

    >
    > Very interesting. I'm going to try this. So to repeat what you've already
    > said.


    As I wrote previously this works only for Nikon Scanners that allow
    adjustment of channels specific exposure ("analog gain")

    > 1) go though the Advanced Workflow.
    > 2) Divide Red base/Green base= 1.5, Divide Red base/Blue base = 1.8, which
    > yields working values of R=1.0 G=1.5, B=1.8
    > 3) Unlock Film Base Color, Preview, Lock Film Base Color again.
    >
    > What's going on with the RGB Exposure during all this?


    It stays constant. Since the analog gain for at least one channel will
    stay 1.0 and analog gain is an exposure multiplier it is a kind of base
    exposure.

    --
    Erik Krause
    Digital contrast problems: http://www.erik-krause.de/contrast
     
    Erik Krause, Jul 7, 2005
    #7
  8. "Alan Smithee" <> wrote in message
    news:Gpeze.1892120$Xk.1886357@pd7tw3no...
    > Bart van der Wolf wrote:
    >> "Alan Smithee" <> wrote in message
    >> news:ElYye.1875764$Xk.596605@pd7tw3no...
    >> SNIP
    >>> What's going on with the RGB Exposure during all this?

    >>
    >> The ratio of R, G, and B exposures is preset by VueScan
    >> when scanning color negatives, and differs between scanner
    >> models. On Nikon Scanners the ratio can be changed by the
    >> user. These ratios are supposed to neutralize the color of the
    >> film mask.

    >
    > Good to hear from you Bart. I have an Epson 3200. I just see
    > one RGB value on my input tab, do Nikon scanners show three
    > where I see one? What exactly is the film base setting(s)
    > doing? Does it adjust gamma or is it changing the exposure
    > ratio for each channel?


    Neither, it determines (in addition to the scanner default R/G/B
    exposure time ratio) the scan's white-point clipping/settings (before
    inverting to positive and Gamma adjustment). Only the Nikons can be
    R/G/B exposure time ratio adjusted by the user.

    > In later releases of Vuescan I can now choose to scan using just one
    > color channel, doesn't this effectively give me the ability to
    > change the
    > RGB ratio?


    Yes, but only if you individually/manually reassemble the R+G+B scans,
    and without registration errors.

    Bart
     
    Bart van der Wolf, Jul 8, 2005
    #8
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