LaserSoft Imaging

Dear forum users,

...recently I bought a DigitDia 4000 including Silverfast AI and an IT8 calibration target.
It seemed to be a no brainer to me that a correct calibration of the input device will yield
optimum results in my scanned files.

Surprisingly I had to find out that with ICM all scanned pictures are now much more
color saturated (more than it would be nice) and also have a noticeable green cast.

I repeated the IT8 calibration several times, yet any of the generated profiles creates
the same results for my scans.

I know that the scanner is not a high-end device, but leaving off ICM creates very
pleasant results (and I currently go for that option).

I have seen many options in SF that may influence the scanned results colors so I
wonder about an objective test if color calibration worked right or not.

My idea is:
1.) scan the IT8 target without ICM -> get an uncalibrated result -> store
<img src="/img/forum/it8correctionoffisrdoff.jpg">

2.) calibrate with this IT8 target having the IT8 reference file at (it was put there automatically)
\Programme\LaserSoft\SilverFast AFL\SilverFast\IT8 Reference Files\LaserSoft Imaging\Transparent\E040625.txt

3.) scan the IT8 target with ICM -> get a calibrated result -> store
<img src="/img/forum/it8correctiononisrdoff.jpg">

4.) measure (read out) the color values of the file from 3.) to see if they
match the officially recommended values for that field.

I did 1-3 already and attach resized (800x512) pictures to this post (see above).
They may have been scanned using incorrect options (from 2 days ago).

My problems:
1.) I am angry that I have to do this , but I am curious
2.) What do I have to care of setting the SF options:
- rendering intent (absolut farbmetrisch?); this should not matter if all colors are within the gammut, right?
- all auto functions off (contrast, color, ACR, etc)
- iSRD off (should not matter anyhow)
- anything else to think of?
3.) Where can I find the correct "reference" values for each of the fields of the IT target?

Is this the right approach?
Are there any tools or debug options in SF that make this unneccesary?

My monitor is not calibrated, but I have no problems with any color casts for my DigiCam
pictures or any other pictures. The color temperature is set to 6500K (LCD 19").

Thanks for reading so far!

Any help on the way?

bye
Tobias

Tobias,

If you want to accurately color manage then you need to start by calibrating your monitor. Other wise it is like taking the time to clean the dust off of the lenses of eye glasses that are shattered.

If you have the IT8 version of SilverFast it is supposed to recognize the bar code on the target and automatically obtain the appropriate reference file. Based on your description it sounds like you are using the target with a non-IT8 version of SilverFast, is that correct?

Hello RAG,

...I am well aware of the monitors influence and this is why I described the procedure in detail.
I wanted to completely outrule any monitors influence by taking the reference chart as the
medium for both, calibration and verification. This must work by the definition of calibration.

To better illustrate the DIFFERENCE I posted both versions and it is up to you all to in the forum
to decide which one comes closer to the real IT8.

And of course I am using the SF AI that has color managment, otherwise I would not have started
the whole thread.

I hope to get a few comment if the validation idea has a flaw or if it has not.
Thinking the calibration issue a little further I think that the final picture cannot correclty
represent the ideal "reference" values of the IT8 target, since it has by itself an "error" built
in, which is why we need the "reference file" to compensate for this.

On the other hand I could think of an improved color calibration process that will do the following:
1.) scan target
2.) calculate ICC by taking the scan 1.) and the reference file into account
3.) (new) rescan and check if the results are as expected

I know that 3.) is not necessary if all components play together well, but
what chance do I have to check?

bye
Tobias

No idea. It should be the other way around. Your uncorrected image looks very much like the "real" target.

Open an editor or word on your monitor as a white surface. Then use this to iluminate your IT8 slide from behind. Then compare it with the colors in the Silverfast preview.

My results are enclosed. Nikon Coolscan

? How to get images in here?

To upload an image click on the
<img src="/img/forum/upload.gif">
just below the message body box where you type your reply.

Then click on the browse button to select the image you want to upload followed by the send file button both of which are shown below.
<img src="/img/forum/upload2.gif">

Then copy one of the two lines highlighted in blue as shown below. The first one will place the image in the post like I have done here, and the second one will place a link to the image in the message.
<img src="/img/forum/upload3.gif">

Dear forum readers,

... I have thought about another method that should outrule any other influence than just
the target and the calibration by SilverFast:

Ideally all IT8 targets from the batch E040625.txt should produce nearly identical output files
AFTER calibration, since the scanners influence is compensated by the calibration process and
the slides from one batch should have very similar properties.

Thus I would really be glad if anyone (including LaserSoft) could post a scan from a calibrated
scanner using the IT8 target E040625.txt for calibration and then scan
the target itself.

Should be the simplest thing, no errors left, except that I have done something wrong
in the scanning of the slide (see my "problems" in my first post).

thanks for your patience,

bye
Tobias

Tobias,

It is my understanding the target contains proper color values, and the reference file contains the values of the target as identified by the manufacture, in this case LaserSoft. In other words the target and the reference file are the known variables. You scan the target and the values from the scan are compared to the correct values located in the reference file. The resulting ICC profile provides the appropriate compensation information for the scanner to use in order to match the known values provided by the target and the reference file.

If I understand you correctly, you are looking for a way to verify the process is in fact working the way it should, right?

I think LaserSoft support is probably the best source for your request since they have the targets and various scanners to do this test.

Hi RAG,

...well I think the story is like that:

1.) you generate an electronic IT8 file, there you can explicitly set all color boxes to the correct values.

2.) you "print" the IT8 file to an output device, here a slide-"printer".

3.) you measure the actual values of the fields in the printed slide and will
find out that they are NOT the "ideal" values as you have planned them to
be. This is because the "printer" and the slide are not ideal either.
If they printer was calibrated for the slide material, it should deliver an ideal output.
So since the printed slide is NOT ideal, you need to document the
difference between the ideal value and the actual measured value of
each field. The result is the "reference file".
Note: "batch measured" IT8 targets are NOT measured individually, but only one of
the batch is. Then slide material and printer settings are left
unchanged and the rest of the batch is considered to behave identical.

4.) If you now use that "non ideal IT8 slide" together with a suitable
reference file for calibration of your own scanner, the result should be
a scanner that can read picture data as they are on the source.

Concluding, this means that an ideal scan of a non-ideal IT-8 target will
deliver a result that will NOT match the ideal IT8 values. This is why I
would trust ONLY a scanned IT8 from the SAME batch for optical comparison.
Mind here that the scan-options need to be standardized as well, otherwise
you compare apples and oranges...

I am hoping for professional advice from LSI so that the issue can be settled.

bye
Tobias

next try to upload

without IT8 profile
<img src="/img/forum/it8_without_scanner_profile_copy.jpg">

with IT8 Profile
<img src="/img/forum/it8_with_scanner_profile_copy.jpg">

Scanner is Nikon Coolscan V

Hello pike105,

...could you please tell me which is your IT8 reference file number?

I wonder if maybe my IT8 target has in reality a slight green cast and
the color adjustment in ICM is not faulty.

AGAIN MY REQUEST TO LSI:
Please supply IT-8 scanned pictures of all your IT-8 targets to get
an easy visual comparison.

I discovered the benefit of the colorwheel to remove color casts in
general from a whole batch of slides, e.g. depending on the slide
material used. Mostly I used FUJI RD100 and a few AGFA CT100.

It would be extremely helpful if LSI could supply reference data for different
popular slide-film materials to correct the color cast of the film itself.
Mind that this "correction" is for the process "reality to film" which is
not covered by any other ICM related correction activity.
I know this maybe hard to do, since some may have used filters
which are not color neutral (Skylight 1a, 1b).
Thus it would be even better to allow a "push-button" correction in
the color wheel area by selection of "filter type" and "slide material".

I noticed that this seems to be done for negative film material, but
I did not go into detail there since I have nothing to scan for that.

Since there is no visible feedback from LSI staff to this thread I fear
that I must open a Support Request for that.

bye
Tobias

i think you may find this of interest.

http://www.littlecms.com/newutils.htm

the demo and utils will give you some information.

regards,

Dear readers, dear LSI Support,

...this is a lenghty post, so please take some time to read.

Let me summarize my ideas regarding a successful and satisfactory
IT8 Calibration for slide scanning.

First a little excursion on the workflow from reality to the scanned
picture on your hard disk (input path). I will have to discuss the output
path (picture on hard disk to printed picture) as well, but mainly
to explain my view on the way how IT-8 targets are created.

Input:
------
1.) Reality, this is the "original" for most people and represents
the real reference that needs to be matched finally.

2.) The slide that took the information from reality and stored
it through the physical and chemical processes applied.

3.) The file that represents the picture in binary format.

Output:
-------
4.) The printer that puts the binary info available onto a
paper with ink or other processes or a slide with light.

5.) The monitor that shows the binary info available on screen.

6.) The slide projector and the canvas.


So now the interesting part is the way that information goes from
one step to the next one. Mind that in each of these steps specific
limitations of the process and/or the target format apply. The main
target of each process is to loose as little information as possible
and to have the result in a format that can keep most of the interesting
information. The latter may lead to results that are not technically
"ideal" but I not an expert in this (yet?).

OK, here we go:

a.) = 1.)->2.) This is simple thing we call "taking a photograph".
In times before digital photography you had to select the slide
material by subjective impression of how much you "liked" the result
after the development process. There was no automatic white balance or
other methods to adjust the process.
So it was extremely hard (if not impossible) to compare reality
with the result and you just compared your memory with the result.
Surely you noticed that different slide materials have different
representations of reality. I liked very much the FUJI RD100 due
to its vital colors and nice representation of the blue sky.
For the AGFA CT100 that I had to take occasionally I must say that
for my liking the brown was to dominant.
In short: All slides have a color cast!

b.) = 2.)->3.) This is the process we call "scanning". Here the
scanner takes a representation of the information found on the slide
and will put this information in an electronic format. Also the scanner
has items that influence the scan results like
- the used light source (RGB Balance)
- the sensitivity of the CCD (Signal to noise ratio, or "Density")
- the resolution
In short: Also the scanner may have a color cast

c.) = 3.)->4.) The "printing" is already at a rather late stage of the
whole process (and makes it difficult to print good pictures).
The data stored in a file need to be output on a medium that
will be viewed later. This needs to done in such a way that the
subjective impression of the viewer is similar to that of the
reality in 1.)

d.) 3.)->5.) The normal viewing process on your monitor. Here it is
important to note that the "white color" is set to a value close
to reality, mostly chosen is 6500K.
Also the monitor has deficiencies showing the RGB values exactly as
they are on file.

e.) 2.)->6.) The projection of the slide onto a canvas.
Here the light source (quartz bulb) and possibly the canvas
influence the viewing result. If you have a dimmable light-source
in your projector, the color of the light will vary dramatically
from red to orange to yellow. The usual maximum temperature of a
quartz bulb is around 3000K (so much lower than sunlight of 5600K).


Summarizing immanent "errors" of the transition processing and the
corrections we find the following:
a.)
error: slide-material
correction: none

b.)
error: scanner-individualities
correction: ICM input calibration (IT8 target + reference file)

c.)
error: printer-paper individualities
correction: ICM output calibration (with a calibrated scanner?)

d.)
error: monitor-individualities
correction: ICM monitor calibration (with a special measurement device)

e.)
error: quartz-bulb temperature color / canvas
correction: none (your eye makes the white balance adjustment)


A brief intermezzo on the "old" method of taking and viewing pictures:
If you look at a.) and e.) you may notice that most slides are
projected with a color temperature that is much lower than the reality
was taken on slide. So a color cast of the slide material in the
direction of higher temperatures (green or blue) may have been a
simple but intended "method" to compensate for his.



Now concluding to the IT8 creation and the use of the targets later
for calibrating a scanner:

Creating an IT8 target is simply printing an electronically created
IT8 layout to an output, e.g. a slide.
Since the output is not ideal as well, the resulting IT8 printout needs
to be measured and the values for each of the fields in the IT8 layout
need to be stored in a file so that later the values retrieved by a scan
process can be compared against the originally measured ones.
This is why the IT8 target needs an accompanying matching reference file!

Mind however that the scan-result of such an IT8 file will create a file
that represents the slide AS IT IS and NOT the ideal IT8 values!



Finally the following questions arise:
1.) Why is the IT8 creation not using a calibrated output device?
This (ideally) should make the use of a reference file unnecessary because
a calibrated output device should print an IT8 target where each of the
color fields has the same color value as the binary IT8 layout had.

2.) The reference file for an IT8 target could easily be used to create
a printer correction? If the reference file tells what the measured
values of the IT8 output fields are, the difference of each measured
value and the binary reference should give the printer correction.

3.) If the slide material has a characteristic color cast build-in, why
not supply correction-references for popular materials in a professional
software dealing with slide-scanning? This way the initial intended
color cast for slides can be eliminated in a comfortable way and the
transition into binary "white balanced" data would be very easy.
-> LSI please take that hint!


OK, I have my lessons learnt and could put together a complete and
logical model of the processes that I know of. This model explains all
the phenomena I came across. It is still simplified in that it deals
with color-cast only (and not much with non-linear response or other
peculiarities), hey but it?s just a hobby...


Thanks for reading so far and following my thoughts. I would really
welcome some feedback, from both the forum readers and the LSI
professionals.


bye
Tobias

Dear readers, dear LSI support (continously ignoring my post)

...finally I extended my investigations of IT8 reference and scanning results also
on the bundled software for that scanner, the CyberView 1.17e.

I admit that there are by far less options to manipulate and thus I was not expecting
any better result there.

But WHAT A SURPRISE! All results are consistently BETTER and CyberView lets you
as well choose the different silde materials to compensate for the process "reality to film",
which SF does NOT!

I will post here now in sequence the following scans of always the same IT8 target that I have
received together with my SilverFast copy.

From my first post:
SF without ICM
<img src="/img/forum/it8sficmoffisrdoff.jpg">

SF with ICM
<img src="/img/forum/it8sficmonisrdoff.jpg">


From today:
CyberView set to "Generic Positive"
<img src="/img/forum/it8cyvgenericpos800x522.jpg">

CyberView set to "Kodak ED3 positive"
<img src="/img/forum/it8cyvkodaked3pos800x522.jpg">

CyberView set to "Kodak Elite Extra 100 positive"
<img src="/img/forum/it8cyvkodakeliteextra100pos800x522.jpg">

Make your choice!

For me now the final conclusion is to drop SilverFast and use the bundled Software.
Still very few positive aspects are left for SF that CyberView does not offer in that quality
(not checked completely though)
- Light adjustment is more variable with SF
- Very comfortable color adjustment (but I don't need it anymore)
- iSRD works a little better than ICE does
This however does not compensate for the many bugs + quirks and not for the bad color reproduction.

If you have a look at my previous post (I know it is a long one), you notice that CyberView
obviously does ALL compensations (color correction AND(!) slide-material correction) while SF
only offers color correction for the slide-to-file process. The results are obvious!

Thank You LSI for letting me find out all that myself and not getting in the way with your opinion.

byebye

Tobias

Tobias,

Thanks for sharing all of this information. I am sorry to hear the SilverFast isn't working for you and wish you good luck with CyberView.

Dear readers,

...luckily my last resort to get another target for calibration has finally
resolved the problem! It seems that my target slide had a problem, either
of beeing to old and thus suffering or beeing otherwise too far away from
the reference file. My better luck with a slightly newer target (E040916
instead of E040625) does not give me much trust in the IT8 target
production of LSI.

I must admit that the profiling process of SF is unrivaled the simplest and
you get a free target with your software. So if you are satisfied with the
results straight away don't bother dealing with all the stuff yourself.

When I find the time I will post some proof here. Some advice:
- if you do not trust the calibration, look out for the free argyll cms package www.argyllcms.com
I calibrated also with this profiler and for me the results in very dark areas
are slightly better using the LUT profile type.
- if you do not trust the SF IT8 target, replace it with another one,
preferrably from another batch or look out for Wolf F a u s t www.targets.coloraid.de.
I have no target (yet) from there so I cannot report any results.

bye
tobbbie