color profile embedding (not conversion) utility?

[Don]

You're mixing up your quotes. That's no me!

I'm not insisting, I'm making a suggestion. It's a good tool in the
toolbox for sure.

As I said "horses for courses" and LAB certainly has its advantages,
just like other color spaces have their advantages.

LAB can simplify color. Again, I guess you will wait for Adobe to get
on board before it's deemed "The next big thing."

I think this is actually aimed at Lorenzo but...

LAB is the "current" thing. I remember reading over in the Photoshop
group a while back that LAB is the color space Photoshop uses
internally. In other words, regardless of the current color space the
actual editing is applied to the internal LAB representation.

That's Lorenzo again! You should only answer one message at a time.

Don.

 

[blumesan]

I am always amazed ('though perhaps I shouldn't be) that the longer
these threads get the further they stray from the original subject.
The OP wanted to know how to assign (or embed) a profile to his image
file before importing it into his editing software. I am assuming the
following: that the image file originated from a scanner (this is a
scanner group), and that the profile he wanted to attach was the
scanner output profile. Once this were done the image file could be
imported into the editing software and converted to any working space
of choice.

I am dealing with a similar if not identical problem. I can profile my
scanner using an appropriate target. I can get the scanner to output a
raw untagged file. Fortunately in Photoshop I can import the untagged
file, assign the custom scanner profile and then convert to the working
color space of my choosing. It would however be more efficient if the
scanner profile were embedded in the image file. If you are trying to
implement color management it's not a good idea to have untagged files
floating around. So if one could get the scanner software to embed the
profile when writing the image data to file, this would solve my
problem and that of the OP.

Any suggestions folks??

Mike.

 

[Don]

I am always amazed ('though perhaps I shouldn't be) that the longer
these threads get the further they stray from the original subject.

Actually, that's the rule... ;o)

Sometimes diversions can be useful when one learns something new
unexpectedly and at other times frustrating when the subject keeps
getting obscured.

The OP wanted to know how to assign (or embed) a profile to his image
file before importing it into his editing software. I am assuming the
following: that the image file originated from a scanner (this is a
scanner group), and that the profile he wanted to attach was the
scanner output profile. Once this were done the image file could be
imported into the editing software and converted to any working space
of choice.

That is correct. However, the diversion occurred not about the color
space profile (scanner output) but about the scanner profile itself.
That is to say, the profile which is not attached but *applied* to the
raw data with the intention of correcting for any inherent scanner
bias.

While the former (color space) profile may be useful it can always be
attached afterwards, however, the latter (scanner) profile is of very
limited (if any?) use because the image will have to be edited.
Indeed, a scanner profile can often cause damage which has to be
"undone" in editing afterwards.

I am dealing with a similar if not identical problem. I can profile my
scanner using an appropriate target. I can get the scanner to output a
raw untagged file.

The important thing to note is that there are two totally different
profiles here: the scanner profile and the color space profile. They
have nothing to do with each other.

Fortunately in Photoshop I can import the untagged
file, assign the custom scanner profile and then convert to the working
color space of my choosing.

Exactly, which is why attaching a color space profile when scanning is
not that important. One can always do it afterwards.

It would however be more efficient if the
scanner profile were embedded in the image file. If you are trying to
implement color management it's not a good idea to have untagged files
floating around. So if one could get the scanner software to embed the
profile when writing the image data to file, this would solve my
problem and that of the OP.

It's just a matter of convenience but the key thing is, even if that
is not done at scan time it can always be done afterwards.

Don.

 

[blumesan]

Don,
Thanks for your response. I quite agree with what you have said,
except for one statement which seems to fly in the face of color
management principles:

While the former (color space) profile may be useful it can always be
attached afterwards, however, the latter (scanner) profile is of very
limited (if any?) use because the image will have to be edited.
Indeed, a scanner profile can often cause damage which has to be
"undone" in editing afterwards.

According to my rudimentary understanding of color management the use
of the scanner profile in conjunction with the working space profile
(and the monitor profile) allows the image to be displayed with colors
as close to those of the original image as possible. Thereby making
editing a bit easier.

Nevertheless I can understand that it may be possible to ignore the
scanner profile when importing a raw image into the editing software.
Simply assign a working RGB profile, carry out whatever color
correction and editing are required and save the file tagged with the
working profile. If in fact the scanner profile can somehow "cause
damage" (something that I have not see suggested before) this may be
the preferred approach. Can you elaborate on this point?

It's just a matter of convenience but the key thing is, even if that
is not done at scan time it can always be done afterwards.

In my case, quite correct; I would still like to know how to implement
it. For the OP who is unable to utilize his scanner profile, I gather
you would tell him: "forget it"

Thanks again,
Mike.

 

[Don]

Don,
Thanks for your response. I quite agree with what you have said,
except for one statement which seems to fly in the face of color
management principles:


According to my rudimentary understanding of color management the use
of the scanner profile in conjunction with the working space profile
(and the monitor profile) allows the image to be displayed with colors
as close to those of the original image as possible. Thereby making
editing a bit easier.

Nevertheless I can understand that it may be possible to ignore the
scanner profile when importing a raw image into the editing software.
Simply assign a working RGB profile, carry out whatever color
correction and editing are required and save the file tagged with the
working profile. If in fact the scanner profile can somehow "cause
damage" (something that I have not see suggested before) this may be
the preferred approach. Can you elaborate on this point?

Hi Mike,

Yes, that's the theory. The problem occurs when what's on the film is
not really what one wants in the end product. And that covers pretty
much every scan. In other words, no matter how faithfully the film was
reproduced, the post-processing in an external editor afterwards is
going to change all that.

So it all depends on how much editing one does afterwards (and that
includes editing in scanner software!). If the scan is used "as is"
(all settings at neutral or off) then, yes, using a scanner and film
profiles will produce what's on the film.

However, if one applies a scanner profile but the profile goes in the
opposite direction of any subsequent edits, it's going to make matter
worse, not better!

Best explained with an example. Let's say your scanner has a tendency
to add blue. Applying a scanner profile will, therefore, remove blue.
For the sake of the argument, let's say you have a daylight film shot
without flash at night and indoors. The shot has a distinct yellow
cast. Applying a scanner profile will remove blue and make the scan
appear even more yellow! That may be an extreme case and I used it
only as an illustration, but it should explain what I mean. (Of
course, there are also profiles to compensate for exactly this case
but that means, again, going against the nominal scanner profile.)

Now, please don't get me wrong, in general, a scanner profile does not
really do that much harm (as the above extreme example may suggest)
and in many (most?) cases a scanner profile will actually help. But my
main point is that it's not really essential like monitor and printer
profiles because the effects of a scanner profile will be changed
during post processing (usually quite radically).

In my case, quite correct; I would still like to know how to implement
it.

That should be the job of your scanner software. I'm not quite clear
what scanner you have but, for example, using Nikon Scan the option is
in Preferences/Color Management under the RGB tab. In there one can
select what color space to tag to the file.

Don.

 

[blumesan]

Don,

Many thanks for your reply. The suggested workflow is quite clear to
me now.

I have a Nikon Supercoolscan 4000ED. Using the Nikonscan software (ver
4.02) I assume that to get a raw (un-messed-with) scan I would turn off
all color management as well as all of the postprocessing options (with
the possible exception of ICE which operates intra rather than post
processing). In this case the software will leave the image untagged.
I can then assign a working space RGB profile when I import the file
into Photoshop.

If I want the software to output a tagged file I have to turn CMS on.
In that case, assuming I understand the manual correctly, the process
is as follows: The software will use one of three built-in profiles
depending on the film type (Color positive, Color negative, Kodachrome)
to translate the raw data into the RGB working space choosen in
Preferences/Color Management, tag the file with the working space
profile and write to disk.

Please let me know if my assumptions are correct.
As my venerable professor used to say "Assumptions are the mother of a
f**k-up"

Cheers,
Mike

 

[Don]

I have a Nikon Supercoolscan 4000ED. Using the Nikonscan software (ver
4.02) I assume that to get a raw (un-messed-with) scan I would turn off
all color management as well as all of the postprocessing options (with
the possible exception of ICE which operates intra rather than post
processing). In this case the software will leave the image untagged.
I can then assign a working space RGB profile when I import the file
into Photoshop.

If I want the software to output a tagged file I have to turn CMS on.
In that case, assuming I understand the manual correctly, the process
is as follows: The software will use one of three built-in profiles
depending on the film type (Color positive, Color negative, Kodachrome)
to translate the raw data into the RGB working space choosen in
Preferences/Color Management, tag the file with the working space
profile and write to disk.

Hi Mike,

Yes, by turning color management system (CMS) off, you'll be able to
produce an untagged file. However, Nikon Scan actually has a specific
option to produce an untagged file even when CMS is on! Simply select
the "Scanner RGB" color space! The difference between that and turning
CMS off is subtle. When you turn CMS off completely, some Nikon Scan
features are disabled, specifically the LCH editor and Unsharp Mask
(and you have to restart NS!). By using "Scanner RGB" color space
those two remain enabled, but the file is still untagged. (For more
see page 89 in the manual or just search for "Scanner RGB".) However,
if you don't plan to edit in Nikon Scan anyway, all that's academic.

There's also another thing and that's scanning "raw" which in context
of scanning has a specific meaning - very close to my heart! ;o)

Skip if you know this already but scanning "raw" means getting the
most from the scanner (maximum bit depth, etc) and not using any of
the editing features of scanner software. As you state above, ICE -
being at least in part hardware based - should be on when applicable.
Some people also scan in linear gamma (1.0) because that's software
too. I do not, for two reasons. One, gamma 2.2 will be the first thing
I would apply before editing anyway and, two, Photoshop's 16-bit mode
is actually 15-bit (!) while Nikon Scan uses all 16-bits when applying
gamma so it's more accurate.

Anyway, there are several reasons why one would want to scan raw, the
main two being:

1. Scanner software editing is really "second best" and with a limited
subset of editing tools. Also, you're forced to work through the
"preview keyhole" instead of blowing up the image to 1600% like in
Photoshop. Although, as mentioned above, Photoshop's 16-bit mode is
actually 15-bit! :-(

2. Archiving. By scanning raw you get the most the hardware can
deliver and you can thereby "freeze" any future deterioration of film.
You would then burn this to DVD/CD or backup in some other way and
work on a copy. This has many advantages. For example, if at a later
date when you get more proficient in Photoshop or, get a new larger
monitor (i.e. change image size) or, simply don't like the edit, etc.
you can always go back to the "virgin" version without having to
rescan which is not only considerably faster but also easier on the
scanner.

One last hint specific to NikonScan and that's Auto Exposure. It tends
to be quite drastic (clipping) especially for negatives so some people
prefer to turn it off and do the exposure manually. The problem is AE
is very "sticky" and hard to turn off. Not only do you have to turn
off Auto Exposure in *all* places i.e. preview (!!!), single and batch
(both positive and negative!) but you have to exit Nikon Scan *and*
turn the scanner off! To be on the safe side, leave it off for a few
seconds. Only then will Auto Exposure really and truly be off! Do note
that, after restarting NikonScan, if at any time afterwards you click
on Auto Exposure - even accidentally or only for preview - it's on
again and you have the repeat the whole procedure to turn it off.

Please let me know if my assumptions are correct.
As my venerable professor used to say "Assumptions are the mother of a
f**k-up"

That's a big assumption he's making! ;o)

Don.

 

[blumesan]

Don,

Again thanks for your reply. Very useful information clearly
presented.

You have now convinced me that I should, in future, scan "raw", and
that I can stop worrying about scanner profiles. I have never used the
editing features of the scanner software, much preferring to do it all
in Photoshop.
One last hint specific to NikonScan and that's Auto Exposure. It tends
to be quite drastic (clipping) especially for negatives so some people
prefer to turn it off and do the exposure manually
I assume this refers to the exposure of the film during scanning. How
does one go about performing the exposure manually?
And one last question: What about the selection of film type in the
scanner software? I don't see any way to bypass this step and this
must surely interpose some software manipulation of the data between
the "raw" scanned data and what is written to the file. Are you of the
school that recommends scanning color negatives as positives and later
reversing in Photoshop?

Thanks again,
Mike.

 

[Don]

One last hint specific to NikonScan and that's Auto Exposure. It tends
to be quite drastic (clipping) especially for negatives so some people
prefer to turn it off and do the exposure manually

I assume this refers to the exposure of the film during scanning. How
does one go about performing the exposure manually?

Hi Mike,

Yes, it's determining exposure using Analog Gain and looking at the
histogram. It's no different to what Auto Exposure does only you have
more control. The idea is to keep increasing exposure until the
histogram data starts to touch the right edge. That's the ideal
exposure where nothing is lost.

There is a catch, however, and that's that those highlights (the
brightest areas of the image) which touch the right edge of the
histogram often don't really contain much information (e.g.
reflections). That's why it's common to set some clipping. The usual
values are between 0.3 and 0.5. The reason you do that is to extend
the part of the histogram with useful information.

For example, you may get a histogram with a "mountain" covering the
left half and then a thin line from the middle to the right edge. It's
often safe to clip that thin line and extend the "mountain" to cover
the whole available area thereby maximizing dynamic range of useful
data. But if that thin line contains data you want to keep then
obviously you don't want to clip. It all really depends on image
content.

In theory, Auto Exposure should not clip if you set clipping to 0 but,
it does especially in case of negatives because of other reasons (the
image is inverted and processed, etc).

Finally, another hint. You can check the highlights in Photoshop by
using the histogram, of course. But there's a catch. The combined
display i.e. Luminance is "weighed". It's not just all three channels
added up but it's ~60% green, ~30% red and ~10% blue. This means that
even though Luminance may not clip, once you look at individual
channels they may (and usually do) clip!

And one last question: What about the selection of film type in the
scanner software? I don't see any way to bypass this step and this
must surely interpose some software manipulation of the data between
the "raw" scanned data and what is written to the file. Are you of the
school that recommends scanning color negatives as positives and later
reversing in Photoshop?

I haven't made up my mind on that yet. I've been wrestling with my
Kodachromes over the last couple of years because Nikons add that ugly
blue cast. That has literally driven me nuts! I ended up scanning each
slide twice, I call it a "twin scan", once for highlight and once for
shadows. I then combine the two using a program I have written. It's a
long story...

Anyway, since I'm now finally getting to grips with that, pretty soon
I'll have to tackle the negatives. My instinct is to use the Nikon
reversal but set the exposure manually. Other than that, turn
everything else off, as usual.

The thinking is the same as for gamma i.e. reversal would be the first
thing I would have to do in Photoshop after scanning anyway, so why
not let Nikon do it 16-bit instead of Photoshop's 15-bit mode. By
setting exposure manually I'd get around the clipping problem. Since
negatives are compressed anyway (unlike slides) there should be plenty
of dynamic range to be very conservative with exposure.

But I'll really have to run some tests first and then see where that
leads me.

Don.

 

[blumesan]

Don,

Many thanks for your reply. I really appreciate your taking the time
to answer my posts. I hope you will forgive my obsession with details,
but I really want to get this technique right.

Yes, it's determining exposure using Analog Gain and looking at the
histogram. It's no different to what Auto Exposure does only you have
more control. The idea is to keep increasing exposure until the
histogram data starts to touch the right edge. That's the ideal
exposure where nothing is lost.

If I understand correctly the procedure (using NikonScan) would be:

1. Turn off color management, editing function and autoexposure.and
make a Preview scan of the image.
2. Open the Curves and Analog Gain Palettes.
3. For each of the color channels in turn; look at the histogram and
make a ballpark adjustment to the analog gain. Since the effect of the
adjustment is not reflected in the histogram in real time, click on
Redraw.
4. Readjust the analog gain settings as needed, redraw again and
repeat until you are happy with the histogram.
5. Ensure that color management, editing functions and autoexposure
remain off. Gamma may be set at 2.2; autofocus and ICE may be engaged.
Perform final scan.

Thanks again for your help.

Mike.

 

[blumesan]

Don,

A quick addendum. I tried the procedure outlined in my last post.
Overall I was pleased with the results. One surprise however: When
importing the image into Photoshop I am informed that the file is
tagged with the sRGB profile. To me this means that the native scanner
data were massaged to convert the image into the sRGB color space. I
thought the idea was to avoid any manipulation to the "raw" data. Can
you comment?

Cheers,
Mike.

 

[John]

Don,

A quick addendum. I tried the procedure outlined in my last post.
Overall I was pleased with the results. One surprise however: When
importing the image into Photoshop I am informed that the file is
tagged with the sRGB profile. To me this means that the native scanner
data were massaged to convert the image into the sRGB color space. I
thought the idea was to avoid any manipulation to the "raw" data. Can
you comment?

Cheers,
Mike.

That is not what is happening really. When you *import* an image into
Photoshop e.g. using TWAIN (as opposed to *opening* an image using
File|Open), Photoshop assigns the current working space profile to the
imported file. You will notice that if you change your current RGB working
space to (say) Adobe RGB (1998), your imported images will be tagged with
this instead.

To avoid this behaviour and end up with an untagged file (if that is what
you want), uncheck 'Preserve Embedded Profiles' in your colour settings.

 

[Don]

Don,

Many thanks for your reply. I really appreciate your taking the time
to answer my posts. I hope you will forgive my obsession with details,
but I really want to get this technique right.

Hi Mike,

My pleasure. I'm glad you find it useful. I've benefited from this
group greatly and it's just my way of giving some of it back.

If I understand correctly the procedure (using NikonScan) would be:

1. Turn off color management, editing function and autoexposure.and
make a Preview scan of the image.
2. Open the Curves and Analog Gain Palettes.
3. For each of the color channels in turn; look at the histogram and
make a ballpark adjustment to the analog gain. Since the effect of the
adjustment is not reflected in the histogram in real time, click on
Redraw.

That would work, with one caveat. Redraw is really only a "guess". It
simply applies a formula to the Preview data to *emulate* Analog Gain
settings. In theory, that should work, but in practice there are
inaccuracies due to various reasons (usually more boost is needed).

If you want to really be sure, you should re-scan with the new
settings. You still have the 8-bit histogram and limited Preview
resolution (see below) but a re-scan would be more accurate.

Of course, a re-scan will take longer, so you'll have to decide if
that extra accuracy is really worth the trouble of waiting for another
preview scan. Try a few tests (examining the full scan in Photoshop
later and compare to NikonScan histogram) and then see. This may be
hard, though, due to 8-bit histograms (see below).

4. Readjust the analog gain settings as needed, redraw again and
repeat until you are happy with the histogram.
5. Ensure that color management, editing functions and autoexposure
remain off. Gamma may be set at 2.2; autofocus and ICE may be engaged.
Perform final scan.

Yes, that's it in a nutshell. You may actually turn Curves panel "off"
by clicking on the checkmark in the upper left palette corner and
turning it into an "x". However, if you keep the curves "flat" (a
diagonal line from lower left to upper right, it's the same thing
because even though the Curves are processed they are flat and should
not affect the image. And you can examine individual channels, etc.

Do note that what you see there is based on the preview image! Nikon
Scan is good in that it actually uses the full 16-bits for the preview
but the resolution is greatly reduced and the histogram display is
only 8-bit. That means once you import the full scan into Photoshop,
there may be some small differences. Do note also that Photoshop
histogram is 8-bit too. If you want more accuracy here's a free 12-bit
histogram you can use as a Photohop plug-in:

http://www.reindeergraphics.com/free.shtml

Look for the "Wide Histogram".

I'm a bit picky and even that wasn't good enough so I wrote my own
true 16-bit histogram. Also, I wanted to run it outside Photoshop. But
the above histogram is quite useful if you care for such level of
detail. I mean, all that's probably overkill, but I mention it just in
case.

Don.

 

[Don]

A quick addendum. I tried the procedure outlined in my last post.
Overall I was pleased with the results. One surprise however: When
importing the image into Photoshop I am informed that the file is
tagged with the sRGB profile. To me this means that the native scanner
data were massaged to convert the image into the sRGB color space. I
thought the idea was to avoid any manipulation to the "raw" data. Can
you comment?

Just to add to what John says, when an image is tagged with a profile
that data in the file is not changed. The tag simply indicates which
profile to use in the future. You can change this tag at any time. The
only time the image data is actually changed is if you select the
Photoshop option "convert to profile".

BTW, when I used NikonScan I always used it standalone and not as
TWAIN from Photoshop. I'm normally doing all this on my notebook and
running NikonScan alone requires far fewer resources. It's also
probably much quicker because the data doesn't have to be passed to
Photoshop which occurs through temporary files, etc.

I also had some problems with my flatbed (which can only be used with
a TWAIN module). Namely, it would occasionally hang bringing Photoshop
down and then I lose all the images in memory. That's why I prefer to
save to disk first, backup, and only then work on a copy.

Don.

 

[Lorenzo J. Lucchini]

On 31 Oct 2005 13:13:58 -0800, "blumesan" <[email protected]>
wrote:

[snip]

In theory, Auto Exposure should not clip if you set clipping to 0 but,
it does especially in case of negatives because of other reasons (the
image is inverted and processed, etc).

Hey, didn't you forget the very main reason why it may clip, i.e. the
tiny size of the preview that Auto Exposure is calculated on...?

"In theory", there are very valid reasons why Auto Exposure cannot
guarrantee zero clipping on a single scan (plus low-resolution preview).

Not to be the devil's advocate (the devil being you here of course ;-),
but you know, using a preview to calculate things cannot only be a
problem when it's LjL doing it!

[snip]

by LjL
(e-mail address removed)

 

[blumesan]

John,

That is not what is happening really. When you *import* an image into
Photoshop e.g. using TWAIN (as opposed to *opening* an image using
File|Open), Photoshop assigns the current working space profile to the
imported file. You will notice that if you change your current RGB working
space to (say) Adobe RGB (1998), your imported images will be tagged with
this instead.

To avoid this behaviour and end up with an untagged file (if that is what
you want), uncheck 'Preserve Embedded Profiles' in your colour settings.

I am sorry if I have not been specific enough about my procedure. I
never use NikonScan as a TWAIN interface to import an image into
Photoshop. I use NikonScan as a stand alone program which scans and
writes the file to disk. Subsequently I close this software and open
Photoshop; then import the file using File | Open. My PS color
management policies are set to use Adobe RGB as the default working
space. Policy is set to "Preserve Embedded Profile" and Profile
Mismatch and Profile Absent warnings are set. Consequently if the file
being opened had no profile embedded I would get a warning informing me
of this fact. However what I do get is a warning informing me that the
file has an embedded profile that does not match my current RGB working
space; and further states that the embedded profile is sRGB.

I can only conclude that the profile was embedded by the scanner
software before writing the file to disk. And no sane software would
embed a color space profile without first converting the file data into
that color space.

Cheers,
Mike.

 

[blumesan]

Don,
Once again thank you for your replies.

Just to add to what John says, when an image is tagged with a profile
that data in the file is not changed. The tag simply indicates which
profile to use in the future. You can change this tag at any time. The
only time the image data is actually changed is if you select the
Photoshop option "convert to profile".

BTW, when I used NikonScan I always used it standalone and not as
TWAIN from Photoshop.

There is a bit of confusion (at least on my part) about the meaning of
a "tagged image". Putting this aside for the moment, the meaning of
"embedded profile" is quite clear. To me, an embedded profile
describes the color space of its associated file. The file was either
created in that color space or subsequently converted (from whatever
color space it was in, e.g. raw scanner) into that color space. Thus
when I find that the file output by the scanner software has an
embedded profile (sRGB) it suggests that the "native" scanner data have
been converted into this color space before writing the file to disk.
That, of course, requires changing the data. [See my previous post to
John which describes my workflow and PS color settings.]


In a second post Don wrote::

"That would work, with one caveat. Redraw is really only a "guess". It
simply applies a formula to the Preview data to *emulate* Analog Gain
settings. In theory, that should work, but in practice there are
inaccuracies due to various reasons (usually more boost is needed).

If you want to really be sure, you should re-scan with the new
settings. You still have the 8-bit histogram and limited Preview
resolution (see below) but a re-scan would be more accurate. "

I'm still a bit confused. When I select Redraw the scanner does a new
Preview scan. I assume therefore that the new histogram is based on
the results of the new Preview rather than a software emulation of the
changed analog gain settings. Nevertheless I can understand that
examining the histogram of a full scan would give a more accurate
representation of the analog gain changes.

"Of course, a re-scan will take longer, so you'll have to decide if
that extra accuracy is really worth the trouble of waiting for another
preview scan."

Your phrase "waiting for another PREVIEW scan" adds to my confusion.
As noted above, when I select "Redraw" the scanner performs another
preview scan.

"Do note that what you see there is based on the preview image! Nikon
Scan is good in that it actually uses the full 16-bits for the preview
but the resolution is greatly reduced and the histogram display is
only 8-bit. That means once you import the full scan into Photoshop,
there may be some small differences. Do note also that Photoshop
histogram is 8-bit too. If you want more accuracy here's a free 12-bit
histogram you can use as a Photohop plug-in:"

It is my understanding that when the image imported into PS was 16 bit,
the histogram display used all 16 bits. I am using PS CS(8). Please
correct me if I am wrong.

Once again thank you for your reply.

Cheers,
Mike.

 

[John]

John,



I am sorry if I have not been specific enough about my procedure. I
never use NikonScan as a TWAIN interface to import an image into
Photoshop. I use NikonScan as a stand alone program which scans and
writes the file to disk. Subsequently I close this software and open
Photoshop; then import the file using File | Open. My PS color
management policies are set to use Adobe RGB as the default working
space. Policy is set to "Preserve Embedded Profile" and Profile
Mismatch and Profile Absent warnings are set. Consequently if the file
being opened had no profile embedded I would get a warning informing me
of this fact. However what I do get is a warning informing me that the
file has an embedded profile that does not match my current RGB working
space; and further states that the embedded profile is sRGB.

I can only conclude that the profile was embedded by the scanner
software before writing the file to disk. And no sane software would
embed a color space profile without first converting the file data into
that color space.

Cheers,
Mike.

In that case, I think the problem is a default EXIF profile. Now that you
mention it, I have had exactly the same problem, and happily, there is a
simple fix.

For some reason, NikonScan writes the sRGB profile in the TIF EXIF data by
default - why, I have no idea. This profile is not actually embedded in the
image, but is in the EXIF data. It is not the correct profile for the image,
which is in fact untagged. The problem is that Photoshop CS2 (and probably
CS as well) by default will assign the EXIF profile in the absence of an
embedded one.

The solution lies in the Preferences, surprisingly not in the Colour
Settings. Go to Edit|Preferences|FileHandling and check 'Ignore EXIF Profile
Tag'. Your images should now open untagged.

I note in your reply to Don, you ask about 'tagging' as opposed to
'embedding'. I must admit, I tend to use these terms loosely. Tagging an
image is, as you suggest, merely assigning a profile to an image in an image
editor. It does not change the data. Embedding is what happens when you
write the image to a file - the ICC profile itself is incorporated within
the image data so that it can be recovered by an image editor, even if the
profile is not installed on that particular computer.

I have to admit, I don't understand how the EXIF profile is implemented -
whether it is simply a tag refering to the profile name or whether the
profile data itself is included in the file. I suspect the former, but I may
be wrong - perhaps others can help here ....

However, the issue here is that the EXIF profile is incorrect in this case.
That would appear to be a problem with NikonScan. You can rest assured that
in NikonScan, if you select either ScannerRGB or turn off colour management
altogether, you will get native scanner RGB, or as Don likes to say
'Uncorrupted data'

 

[blumesan]

Hi John,

You are right on the money. Checking "Ignore EXIF Profile Tags" in PS
Preferences does the trick. On import into PS the warning shows: no
embedded profile.

I was not aware that the entire profile itself (the lookup table) was
ever embedded into an image file; I thought that just the profile
designator was included. However what you say makes sense since, in
some circumstances the destination software may not have independent
access to the profile.

As for my understanding of "tagging", I always assumed that this was
simply an instruction to the editing software telling it to disregard
the embedded profile (or absence thereof), assume the file is in color
space X and assign that profile as the document working space, (i.e.
tag the file with that profile). No data conversion occurs, and the
file is saved with its original profile (or no profile). I welcome any
corrections or additions to this hypothesis.

Thanks again for your input.
Cheers,
Mike

In that case, I think the problem is a default EXIF profile. Now that you
mention it, I have had exactly the same problem, and happily, there is a
simple fix.

For some reason, NikonScan writes the sRGB profile in the TIF EXIF data by
default - why, I have no idea. This profile is not actually embedded in the
image, but is in the EXIF data. It is not the correct profile for the image,
which is in fact untagged. The problem is that Photoshop CS2 (and probably
CS as well) by default will assign the EXIF profile in the absence of an
embedded one.

The solution lies in the Preferences, surprisingly not in the Colour
Settings. Go to Edit|Preferences|FileHandling and check 'Ignore EXIF Profile
Tag'. Your images should now open untagged.

However, the issue here is that the EXIF profile is incorrect in this case.
That would appear to be a problem with NikonScan. You can rest assured that
in NikonScan, if you select either ScannerRGB or turn off colour management
altogether, you will get native scanner RGB, or as Don likes to say
'Uncorrupted data'

John

..

 

[blumesan]

Hi Don,

On the chance you may have missed my reply to this message (#38) it is
just above in message #37, in my reply to John.

Many thanks for the link to the wide histogram. That is a vast
improvement. It's a pity that it doesn't function in real time
simultaneously with editing the image with the Levels adjustment. But
one shouldn't look a gift horse in the mouth.

Cheers,
Mike.