Creating an accurate scanner profile?

Hello all,

I've purchased some IT8 targets for Provia and Kodak from Wolf Faust.
I've made a few profiles but am not completely happy with my results.
I've made profiles before with a Kodak Q60 target and got decent
results so I'm not sure if it is something I'm doing or maybe the
target/reference.

Here's what I've tried. I first scan the target on my Minolta 5400
with auto exp off, no color management, and no adjustment. I tried
making profiles with Little CMS, Diblook and Monaco EZ color. What I'm
finding is that the colors on the target from B13-B19 are almost
white. If you don't know what I'm talking about have a look at
http://www.targets.coloraid.de/ (B13-B19). I don't know why this range
isn't getting picked up (or getting whited out). I tried with scans
that were multisampled at x1, x4 and x16 but didn't find much
difference in the profiles.

Has anyone encountered this type of problem or have any idea how to
solve it?

On a side note: With little CMS should I be using the "patched
qtscanner profiler for film" or the original one that came in the zip
file (downloaded from http://www.littlecms.com/profilers.htm) to
produce the most accurate results? They seem to be very different in
file size and results.

Also with Little CMS is there a way to load a 16 bit Tiff file? If not
am I sacrificing accuracy by converting to another format like PNG and
8bit? What is suggested?

And lastly is there any trick to using Monaco EZ color? I can't seem
to find any way to get to a options screen when creating a profile.

I guess the question is what do I need to do to get the most accurate
profile?

Thanks,
Patrick

Patrick P. schrieb:

Patrick,

>On a side note: With little CMS should I be using the "patched
>qtscanner profiler for film" or the original one that came in the zip
>file (downloaded from http://www.littlecms.com/profilers.htm) to
>produce the most accurate results? They seem to be very different in
>file size and results.
>
probably rather the new Beta profiler at
http://www.littlecms.com/lcms_profiler_beta_3.exe

Btw, is your scanner color space an approx. linear
(gamma=1) one? At least the old, open-source LCMS
profiler had accuracy problems with linear scans.

>Also with Little CMS is there a way to load a 16 bit Tiff file?
>
Yes, with tifficc you can also apply profiles to 16bpp tiff
files (use the -w option, if you also want 16bpp output).

Regards,
Gerhard

Gerhard,

> probably rather the new Beta profiler at
> http://www.littlecms.com/lcms_profiler_beta_3.exe

Thanks for the reply. I'll try the new beta version when I get home
from work.

> Btw, is your scanner color space an approx. linear
> (gamma=1) one? At least the old, open-source LCMS
> profiler had accuracy problems with linear scans.

Not sure how to tell. My scanner has 3 options, '8 bit', '16 bit' and
'16 bit linear'. I normally go with '16 bit' over the '16 bit linear'
option because the linear file requires a lot of photoshop work to get
it to look right and I haven't seen any benifit.

Thanks,
Patrick

Patrick,
For the current version of the LCMS profiler (which you are using), the
"patched" one is the right
one to use. The non-patched one (in the ZIP) has a very fundamental
whitepoint bug, however, the
degree that the bug will affect images will depend on how far off neutral
the raw scans
are to start with. Using the Viewscan software, which does produce
significantly off-neutral
raw scans, the non-patched profiler was unusable IMHO.

Greg.

(my comments regarding Viewscan apply to my scanner - not sure about yours.
I have the Nikon LS40)

"Greg" <REMOVEskip197@THISbigfoot.com> wrote in message
news:40a2a155$1@duster.adelaide.on.net...
> Patrick,
> For the current version of the LCMS profiler (which you are using), the
> "patched" one is the right
> one to use. The non-patched one (in the ZIP) has a very fundamental
> whitepoint bug, however, the
> degree that the bug will affect images will depend on how far off neutral
> the raw scans
> are to start with. Using the Viewscan software, which does produce
> significantly off-neutral
> raw scans, the non-patched profiler was unusable IMHO.
>
> Greg.
>
>

Hi Patrick,

Regarding the nearly white patches in the B row, -try resetting your
scanner by pressing CTRL+SHIFT+I. This has often worked for my scanner
(Minolta Scan Elite II). Might be a good thing to do before you start
scanning a lot of slides.

The beta LCMS is very different from the other LCMS package. You
should be able to produce pretty good profiles for your scanner,
however keep in mind that the film has to be exposed and developed
perfectly... At least you have a much better file to work with after
applying the profile in Photoshop. Some adjustments are often required
but much less than if you didn't have the profile. Remember to NOT
apply any colour space in your scanner driver.

Please tell what you think of your results.

Oistein



n1patrick@hotmail.com (Patrick P.) wrote in message news:<9d77ae76.0405120149.602ec04a@posting.google.com>...
> Gerhard,
>
> > probably rather the new Beta profiler at
> > http://www.littlecms.com/lcms_profiler_beta_3.exe
>
> Thanks for the reply. I'll try the new beta version when I get home
> from work.
>
> > Btw, is your scanner color space an approx. linear
> > (gamma=1) one? At least the old, open-source LCMS
> > profiler had accuracy problems with linear scans.
>
> Not sure how to tell. My scanner has 3 options, '8 bit', '16 bit' and
> '16 bit linear'. I normally go with '16 bit' over the '16 bit linear'
> option because the linear file requires a lot of photoshop work to get
> it to look right and I haven't seen any benifit.
>
> Thanks,
> Patrick

Hi Patrick,

Regarding the nearly white patches in the B row, -try resetting your
scanner by pressing CTRL+SHIFT+I. This has often worked for my scanner
(Minolta Scan Elite II). Might be a good thing to do before you start
scanning a lot of slides.

The beta LCMS is very different from the other LCMS package. You
should be able to produce pretty good profiles for your scanner,
however keep in mind that the film has to be exposed and developed
perfectly... At least you have a much better file to work with after
applying the profile in Photoshop. Some adjustments are often required
but much less than if you didn't have the profile. Remember to NOT
apply any colour space in your scanner driver.

Please tell what you think of your results.

Oistein


n1patrick@hotmail.com (Patrick P.) wrote in message news:<9d77ae76.0405120149.602ec04a@posting.google.com>...
> Gerhard,
>
> > probably rather the new Beta profiler at
> > http://www.littlecms.com/lcms_profiler_beta_3.exe
>
> Thanks for the reply. I'll try the new beta version when I get home
> from work.
>
> > Btw, is your scanner color space an approx. linear
> > (gamma=1) one? At least the old, open-source LCMS
> > profiler had accuracy problems with linear scans.
>
> Not sure how to tell. My scanner has 3 options, '8 bit', '16 bit' and
> '16 bit linear'. I normally go with '16 bit' over the '16 bit linear'
> option because the linear file requires a lot of photoshop work to get
> it to look right and I haven't seen any benifit.
>
> Thanks,
> Patrick

Greg,

Are you saying that a raw scan with minimal colour cast is "easier"
for LCMS to handle than a raw scan with e.g. a strong red cast? I
thought the whole point was to let LCMS handle the raw scan (i.e. NOT
colour adjusted in ANY way) so as to produce profiles for colour
correction?!

Oistein


"Greg" <REMOVEskip197@THISbigfoot.com> wrote in message news:<40a2a18e$1@duster.adelaide.on.net>...
> (my comments regarding Viewscan apply to my scanner - not sure about yours.
> I have the Nikon LS40)
>
> "Greg" <REMOVEskip197@THISbigfoot.com> wrote in message
> news:40a2a155$1@duster.adelaide.on.net...
> > Patrick,
> > For the current version of the LCMS profiler (which you are using), the
> > "patched" one is the right
> > one to use. The non-patched one (in the ZIP) has a very fundamental
> > whitepoint bug, however, the
> > degree that the bug will affect images will depend on how far off neutral
> > the raw scans
> > are to start with. Using the Viewscan software, which does produce
> > significantly off-neutral
> > raw scans, the non-patched profiler was unusable IMHO.
> >
> > Greg.
> >
> >

"Oistein" <oisteinthomassen@hotmail.com> wrote in message
news:5c9c9d60.0405130233.4025129a@posting.google.com...
> Are you saying that a raw scan with minimal colour cast is "easier"
> for LCMS to handle than a raw scan with e.g. a strong red cast?

Yes, but *only* for the buggy version. The bug is fixed in the "patched"
version.

> I thought the whole point was to let LCMS handle the raw scan (i.e. NOT
> colour adjusted in ANY way) so as to produce profiles for colour
> correction?!

Exactly. If you use the patched version of the profiler, it will do this
properly.
(or the more recent profiler, presumably - I haven't tried it yet, though)

Greg.

Oistein,

Yes I did try ctr-shift-i and got better results. The result still
doesn't look exactly like the target slide but it is closer.

What concerns me now is that I'm getting dE maximums of 4 to 6.5. I
get this with diblook and Monaco EZ color as well. Apparently the
human eye can't detect differences of dE=3 to dE=6. I'm getting
worried that I'm right at the edge of the max. How can I lower this? I
tried scanning with different settings but get around the same result.
Does it have to do with the scanner being far off from what the target
is? If so maybe there is something wrong with my scanner. Any thoughts
are welcome.

By the way I'm using a Minolta 5400.

Patrick