General question to scanner software

Discussion in 'Scanners' started by Max Perl, Oct 21, 2007.

  1. Max Perl

    Max Perl Guest

    When you after a prescan adjust the histogram for darkest and lightes point.
    Is this a post processing only? .....or will it adjust the A/D converter
    to place all its 16 bits (0 - 65535 gray levels)
    inside the darkest and lightes point so you get a better dynamic range in
    your scan?

    If it is not so......then you could just make some raw scans and finish the
    job i Photoshop and get the same result?

    Max
     
    Max Perl, Oct 21, 2007
    #1
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  2. Max Perl

    JimKramer Guest

    Depends...

    You may be able to adjust the analog gain or the exposure. Both of
    these will effect where those bits fall in the range from black to
    white.

    Best answer. Play with the scanner and learn how to use it to make you
    happy. Some people are perfectionists and others are content with
    factory settings. :)

    Good luck
    Jim
     
    JimKramer, Oct 21, 2007
    #2
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  3. I get the impression that Max knows how to use the scanner and doesn't
    have to play with it. The question would seem to have technical merit,
    even if the answer were simple. I suspect it's not.

    My response to the question would be that scanner software is not
    standardized, so the two approaches may be equivalent, but maybe not,
    depending on the scanner. How accurate is the scanner histogram? And
    are you throwing away information in relying upon factory settings?

    With that in mind, I do only "raw" scans (Nikon 4000ED) and put off
    fixing the black and white points until I open the file in PS/CS2.

    HFL
     
    Harry Lockwood, Oct 21, 2007
    #3
  4. Max Perl

    JimKramer Guest

    Max mentioned 16 bit scans and to my knowledge the "best" scanner is
    still limited to 14 bits.
    The histogram is meaningless before the fact. If the exposure/analog
    gain is to low then dark details will become black and highlights will
    become grays and vise versa if it is set too high.
    Are you dealing with 16 bit Tiff's or are you using jpegs from the
    scanner?
     
    JimKramer, Oct 21, 2007
    #4
  5. True. The scan is at 14 bits, but the file is stuffed to 16 bits. So,
    it's usually (but incorrectly) referred to as a 16 bit scan. But the
    intent of the question is valid no matter the bit depth of the scan.
    I agree. I was assuming a properly exposed negative. Otherwise, I
    adjust the analog gain. After which, Max's question reemerges.
    Jpegs from the scanner? Surely, you jest.


    HFL
     
    Harry Lockwood, Oct 21, 2007
    #5
  6. Max Perl

    That_Rich Guest

    Yep, same here.
    No adjustments in scanning software (vuescan) .... everything else in
    PS.

    RPĀ©
     
    That_Rich, Oct 21, 2007
    #6
  7. Max Perl

    JimKramer Guest

     
    JimKramer, Oct 21, 2007
    #7
  8. Max Perl

    Max Perl Guest

    I have a CoolScan 9000 ED and as far as I remember I choose 16 bit in the
    menu. It is possibly only 14 bits internal but thought this was the main
    difference
    between the 8000 and 9000.....that they enhanced it from 14 to 16 bits.

    The main question was just if I gain something by finetune the histogram in
    the scanner software just after the prescan. If not I would prefer just to
    use
    Photoshop to adjust the image.
     
    Max Perl, Oct 21, 2007
    #8
  9. Max Perl

    Matthew Winn Guest

    Apart from adjusting the exposure to correct grossly over or under
    exposed images, I don't think there is anything you can do.

    Suppose the scanner offers 14-bit resolution over its full range, and
    imagine you're scanning an image that uses only a quarter of that
    range. That would usually give you 12 bits of useful data. If the
    scanner hardware were capable of narrowing its sensitivity to use all
    14 bits to cover the one quarter spanned by the range of the image
    then it must also be capable of using 16 bits for its entire range,
    in which case its specification would state that it had 16 bits.
     
    Matthew Winn, Oct 22, 2007
    #9
  10.  
    Harry Lockwood, Oct 22, 2007
    #10
  11. Max Perl

    JimKramer Guest

     
    JimKramer, Oct 23, 2007
    #11
  12.  
    Harry Lockwood, Oct 23, 2007
    #12
  13. Max Perl

    JimKramer Guest

     
    JimKramer, Oct 23, 2007
    #13
  14. Max Perl

    Max Perl Guest

     
    Max Perl, Oct 23, 2007
    #14
  15. YET ANOTHER BIG SNIP

    Based upon these comment about 400CN, I think I'll go back and do a more
    thorough comparison with XP2. Thanks, Jim and Max.

    HFL
     
    Harry Lockwood, Oct 23, 2007
    #15
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