Scanner profiling with Nikonscan 4.0.2

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odesmaison

I know this is an eternal question that have come up in the past and I
thouroghly review the archive for 4 days without finding.

First, the subject says it : I'd like to generate custom profiles, so
any indications to best use the scanner (LS-50) and driver is welcome,
but somehow off-topic, so would be recommendations for third part
driver.

Here is what I roughly undertsand (roughly being the key word) :

-the Nikon CMS will always apply (convert) a low-level profile e.g.
NKLS50.icm and NKLS50_P.icm for positive scanning, this would be
assumed profiles. I assume they do not prevent profiling (?).

- in stand alone mode like in twain mode a tag is added in the TIFF but
only in the EXIF, it does not "corrupt" the file. Twain does not pass a
profile anyway (?).

- Auto-exposure does not prevent a color-managed worklow, in the sense
that it maximise the dynamic range of the output by defining the
intensiy at which the CCD wouls saturation, but light being stable and
the scanner self calibrated, it does not impact on hue and saturation.
Just luminance is at stake. Again profiling should (?) be correct under
those circumstances.

- Gamma is set once and for good, and while determine best use of bits
available. I have seen various references-recommandation anywhere from
1.8 to 2.8 (on XP). Ultimately it seems that the best gamma is the one
that provides a match between various patches of the target grayscale
and the reference file measures. This is debatable and advises are
welcome.

Now this would call for simply : turning off NK CMS (with all the
turning off of the driver, the scanner...), keeping auto-exposure on,
determine best gamma and go for the target scan and actual scans. Well,
this gives me below enthusiastic results with a profile generated by a
Monaco commercial package.

At reading knowlegdable people (D. Hitcheson, B Fraser, A Rodney...),
there is much than this to properly profile a scanner :

1. Black point and white point (Dmin-Dmax) need to be determine and
set.
2. While the scanner self calibrates, this does not necessarily provide
a grey balanced response, and best TRC (and gammaTRC) needs to be set
for each R,G,B.

So my questions are 1) am I correct is the above assertions ; 2) how
can I Dmin-Dmax together with TCRs to profile the scanner. I have a
feeling I just ... can't.


Olivier
 
I know this is an eternal question that have come up in the past and I
thouroghly review the archive for 4 days without finding.

First, the subject says it : I'd like to generate custom profiles, so
any indications to best use the scanner (LS-50) and driver is welcome,
but somehow off-topic, so would be recommendations for third part
driver.

Here is what I roughly undertsand (roughly being the key word) :

-the Nikon CMS will always apply (convert) a low-level profile e.g.
NKLS50.icm and NKLS50_P.icm for positive scanning, this would be
assumed profiles. I assume they do not prevent profiling (?).

- in stand alone mode like in twain mode a tag is added in the TIFF but
only in the EXIF, it does not "corrupt" the file. Twain does not pass a
profile anyway (?).

- Auto-exposure does not prevent a color-managed worklow, in the sense
that it maximise the dynamic range of the output by defining the
intensiy at which the CCD wouls saturation, but light being stable and
the scanner self calibrated, it does not impact on hue and saturation.
Just luminance is at stake. Again profiling should (?) be correct under
those circumstances.

- Gamma is set once and for good, and while determine best use of bits
available. I have seen various references-recommandation anywhere from
1.8 to 2.8 (on XP). Ultimately it seems that the best gamma is the one
that provides a match between various patches of the target grayscale
and the reference file measures. This is debatable and advises are
welcome.

Now this would call for simply : turning off NK CMS (with all the
turning off of the driver, the scanner...), keeping auto-exposure on,
determine best gamma and go for the target scan and actual scans. Well,
this gives me below enthusiastic results with a profile generated by a
Monaco commercial package.

At reading knowlegdable people (D. Hitcheson, B Fraser, A Rodney...),
there is much than this to properly profile a scanner :

1. Black point and white point (Dmin-Dmax) need to be determine and
set.
2. While the scanner self calibrates, this does not necessarily provide
a grey balanced response, and best TRC (and gammaTRC) needs to be set
for each R,G,B.

So my questions are 1) am I correct is the above assertions ; 2) how
can I Dmin-Dmax together with TCRs to profile the scanner. I have a
feeling I just ... can't.


Olivier
Click to expand...
Disclaimer:
I do not own a Nikon film scanner. I know little about profiling a scanner.

After saying the above, this is what I think I know.
1. You can not "profile" a scanner. If you have a "profile" you probably
should remove it. NKLS50_P.icm is a Color Management file. And you should
use it as the default for that scanner.

You can use configuration for certain Color Negatives. Kodak has a different
response than say FujiFilm. Even from one batch to another batch of negative
film you will get a different color response.

Slides will often be fine in the color balance department, maybe a black and
white point adjust for better contrast and brightness.

2. Auto exposure works pretty well most of the time. You will always run
into film that was just a bad exposure and you have to tweak the white and
black points to even see something.

3. TWAIN interface does not support any Meta data. All that TWAIN delivers
is the Image pixels and the scanner resolution.

4. Any Color Management is done in the Photo Editor and in the Computers
Color space. Color Management is a whole another can of worms. If you use
the same color space for every device on your computer system, things work
well. sRGB is the most common.

5. Gamma. Use what looks good for your system. Every Photo editor will use
it own Gamma. My computer system apparently uses 2.0 for its gamma.

6. There are Color Management devices and software to calibrate your
computer system, Monitor and Printer to produce the same color appearance
from one device to another device.
 
should remove it. NKLS50_P.icm is a Color Management file. And you should
use it as the default for that scanner.
Click to expand...

This is a very valid point. The question being with CMS off is that
profile really applied to file values ?
You can use configuration for certain Color Negatives. Kodak has a different
response than say FujiFilm. Even from one batch to another batch of negative
film you will get a different color response.
Click to expand...

True, but this is not really an issue : you just get what the slide
looks like, discreapancies included, like you would in any other case.
Slides will often be fine in the color balance department, maybe a black and
white point adjust for better contrast and brightness.
Click to expand...

Well, I'm not sure, when you scan a target, RGB of any grey patch are
not equal, and reference file figures show better neutrality. So IMHO
there's room for improvement.
2. Auto exposure works pretty well most of the time. You will always run
into film that was just a bad exposure and you have to tweak the white and
black points to even see something.
Click to expand...

Yes, but I have not yet been able to determine whether a change of
exposure corrupts a profiled output or nor. I tend to recall someone
mentionning no but I'm uncertain
3. TWAIN interface does not support any Meta data. All that TWAIN delivers
is the Image pixels and the scanner resolution.
Click to expand...
Yes and with NS, it seems the file get a sRGB tag in the EXIF (correct
?).
4. Any Color Management is done in the Photo Editor and in the Computers
Color space. Color Management is a whole another can of worms. If you use
the same color space for every device on your computer system, things work
well. sRGB is the most common.
Click to expand...

Yes, but I would thus need to profile to assign and after convert to
working spaces.
5. Gamma. Use what looks good for your system. Every Photo editor will use
it own Gamma. My computer system apparently uses 2.0 for its gamma.
Click to expand...
I believe I simply don't understand scanner Gamma and how to set it. I
know the theory but can't apply it here.
6. There are Color Management devices and software to calibrate your
computer system, Monitor and Printer to produce the same color appearance
from one device to another device.
Click to expand...

Which fortunately I have, but equipement without competence is a bit
useless for me. Displays and printers profiling, I'm quite at ease
given what I need to produce, but the LS-50 and NS4 CMS have lost me.Olivier
 
This is a very valid point. The question being with CMS off is that
profile really applied to file values ?


True, but this is not really an issue : you just get what the slide
looks like, discreapancies included, like you would in any other case.


Well, I'm not sure, when you scan a target, RGB of any grey patch are
not equal, and reference file figures show better neutrality. So IMHO
there's room for improvement.


Yes, but I have not yet been able to determine whether a change of
exposure corrupts a profiled output or nor. I tend to recall someone
mentionning no but I'm uncertain
Yes and with NS, it seems the file get a sRGB tag in the EXIF (correct
?).


Yes, but I would thus need to profile to assign and after convert to
working spaces.
I believe I simply don't understand scanner Gamma and how to set it. I
know the theory but can't apply it here.


Which fortunately I have, but equipement without competence is a bit
useless for me. Displays and printers profiling, I'm quite at ease
given what I need to produce, but the LS-50 and NS4 CMS have lost me.
Click to expand...

I think NS4 CMS is out of my range also. Although there is a lot of
discussion and the occasional tutorial if you search Google for "NS4 CMS"
without quotes.

Color Management is a tough subject. I am not the person to help in that
area.
I do well with the default for my system. My scanner is not using color
management. Mainly because I have it turned off.

I have a Canon Canoscan 8400F and in the Preferences, Color Settings tab I
have selected "Recommended". (On this Canon you have to be in the Advanced
Mode to get the preferences button).

There is a color management setting where you can select the source and
target. Source(CanoScan 8400F Reflective) Target(sRBG IEC61966-2.1)

On this scanner, if you select those color management settings, you can not
adjust any of the scan parameters. (They are grayed out). But it does a nice
job, looks just like the folder I scanned.
 
Well, I don't want to sound like I know all about CM, and I am one of
the "Raw Scan Fundamentalists" (once so called in a past thread).

I have not yet found a reason for stating that NS CMS is doing a poor
job, and the s/w has more capabilities than I can use.

However, I have some output equipment with gamut larger than AdobeRGB
and want to benefit from large gamut spaces. The one provided by NS is
WideGamut RGB. This space suffers from non-homogeneity e.g. the "blue
turns purple" issue is a serious one. I would like to use in Prophoto
(as I do with DSLR files) which is not a NS4 option.

Olivier
 
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