Incorrect exposure of high bit scans

All the problems with Nikon film scanners

t90
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Incorrect exposure of high bit scans

Postby t90 » Mon Mar 07, 2005 2:00 am

When using Silverfast ai with the Nikon Coolscan 4000, I obtain very good results when scanning negatives (using negative direct) in 24 bit mode, color management enabled. As soon as I switch to 48 bit mode (all other settings unchanged) the scans come into Photoshop overly dark and contrasty.

Is this a known issue or am I doing something wrong?

degrub
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Postby degrub » Mon Mar 07, 2005 3:16 am

are you in 48 bit or 48 bit HDR ? HDR would come in dark.

t90
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Postby t90 » Mon Mar 07, 2005 3:27 am

It does not seem to matter. 48 bit looks much the same as 48 bit HDR. One other bit of info: I am using Nikon's NKLS4000LS40.icm profile for my Input profile. A screen shot of the CMS setup can be seen here:

Image

BB
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Postby BB » Mon Mar 07, 2005 8:47 am

You might want to try NKLS4000LS40_N_14.icm. It's the profile for 14-bit color depth, I don't know if this will solve your problem, but I remember that it used to make a difference in my setup.

On Mac OSX this should be located in /Library/Application Support/Nikon/Profiles/, but I don't know where it is in Windows...

HTH
BB

t90
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Postby t90 » Mon Mar 07, 2005 10:57 am

Windows does not recognize ANY Nikon color profile with an underscrore in its name, including NKLS4000LS40_N_14.icm, as being a valid color profile, and therefore it cannot be installed. It exists, apparently, only for the exclusive use of the Nikon software. It is not an option in the Silverfast dialog.

BB
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Postby BB » Mon Mar 07, 2005 11:22 am

Strange; does this affect only the file name (then you could simply rename it), or the Name stored in the icc profile itself? Then you can open it in a binary editor (or Emacs) and replace the corresponding underscores (just do not simply delete them, because this might corrupt the profile).
I'll have to give it a try on my spare Windows machine later that day...

BB

t90
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Postby t90 » Tue Mar 08, 2005 3:01 am

I've had no luck renaming the 14 bit Nikon profile, although I'm not sure it would matter. The default profile (NKLS4000LS40.icm) works fine with positive film.

I have found a workaround of sorts. I went into the Options>General tab and set Gamma Gradation to 2.2 AND checked the HDR box. Now when I scan a negative using 48 Bit HDR Colour it turns out well--in other words, it now matches the Preview. The great drawback to this method is that none of the tools for image correction is available. This change did not affect scanning in 48 Bit mode, however. That setting remains unusable for negative film.

BB
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Postby BB » Wed Mar 09, 2005 9:42 pm

I had no success installing the profiles (any Nikon profile!) in Windows, no idea why. However, if I understand it correctly, checking the HDR box only causes the gamma value to be applied in an HDR scan (which is what you do then, scanning raw data without the possibility to use the image manipulation tools). The reason for the normal 48 bit scan not working must be something completely different (though I have no idea what, because your CMS settings look ok; sorry :-( The only thing I would do is to select "ICM" also in the internal->monitor section, but I'm not sure if this would improve things)

BB

t90
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Postby t90 » Wed Mar 09, 2005 11:59 pm

I had no success installing the profiles (any Nikon profile!) in Windows


Nikon stores the profiles that can be utilized by Windows in the default system color folder (C:\WINDOWS\system32\spool\drivers\color), and those will install fine.

I tried changing the monitor setting, to no avail. I guess if I want to scan a neg in 48bit color I'll use NikonScan.

Thanks for your efforts.


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