Bad scanner profiling with Vuescan ?

[Jean Delmas]

I got IT8 scanner profiling targets to Wolf Faust. But I don't succeed
making a good profile for my Canon1220U flatbed Scanner. I tried
several times with flatbed scanner profiling target and even with A4
camera profiling target, but I get quite strong pink cast (similar to
pink cast I get with standard Canon software ScanGear and no
profiling).

My workflow for profiling scanner :

- Set "Input|Scan task" to "Profile scanner"
- Rename Wolf Faust IT8 description .txt file "scanner.it8" and copy
it to my personal folder for vuescan parameters : "My Documents \...\
Vuescan"
- Set "Color|Scanner color space" to "ICC profile"
- Put the file path of the ICC profile "My Documents \...\ Vuescan \
Canon1220U.icc" into "Color|Scanner ICC profile".
- Put the file path "My Documents \...\Vuescan\scanner.it8" into
"Color|Scanner IT8 data
- Press "Preview" button
- Rotate image to upright position (landscape orientation)
- Adjust cropping until IT8 outline matches (not all boxes outlined)
- Choose "Profile|Profile scanner" from the drop-down menu
- The ICC profile is written as "scanner.icc" in folder "My Documents
\...\ Vuescan"


My workflow for scanning with profiled scanner :

- Set "Input|Scan task" to "Scan to file"
- keep "Color|Scanner color space" to "ICC profile"
- keep the file path of the ICC profile "My
Documents\...\Vuescan\Canon1220U.icc" into "Color|Scanner ICC
profile".
- keep the file path "My Documents\...\Vuescan\scanner.it8" into
"Color|Scanner IT8 data
- Press "Preview" button ….

I have to add that I always set "Monitor color space" to "ICC profile"
, "Monitor ICC profile" to my monitor profile and "Output color space"
to "Adobe RGB"

Something wrong ?

 

[Erik Krause]

Hello, Jean Delmas
you wrote...

[...]

- The ICC profile is written as "scanner.icc" in folder "My Documents
\...\ Vuescan"


My workflow for scanning with profiled scanner :

- Set "Input|Scan task" to "Scan to file"
- keep "Color|Scanner color space" to "ICC profile"
- keep the file path of the ICC profile "My
Documents\...\Vuescan\Canon1220U.icc" into "Color|Scanner ICC
profile".

You would have to use previously saved "scanner.icc" instead of course.

- keep the file path "My Documents\...\Vuescan\scanner.it8" into
"Color|Scanner IT8 data

no need for this...

 

[Jean Delmas]

Hello, Erik,
Thanks for your answer. But, infortunately, the mistake that you have
found is only in my message and not in my true workflow...

This is wrong :
- The ICC profile is written as "scanner.icc" in folder "My Documents
\...\ Vuescan"

My true workflow is of course :
- The ICC profile is written as "Canon1220U.icc" in folder "My
Documents
\...\ Vuescan"

 

[Jean Delmas]

I have mesured grey colors with Photoshop CS on 3 IT8 target scans :

1 - VuescanScan with "Color | ICC profile" set to "Canon1220U.icc"
(ICC profile made with Vuescan)

2 - Vuescan with "Color|ICC profile" set to "Built-in"

3 - Scangear, regular Canon software

1-Vues-profiled 2-Vues-built-in 3-Scangear
Grey No 12 16 20 Bk 12 16 20 Bk 12 16 20 Bk
R 113 79 55 45 103 69 46 38 91 45 13 7
V 107 72 45 35 102 68 42 33 94 55 17 9
B 110 73 43 34 105 69 41 32 91 52 15 7

These measurements results are quite strange for a non-expert like me.
Main interesting conclusion is : red color cast is stronger on
"profiled" scanner than on "non-profiled scanner" !!

What is wrong ?

 

[Erik Krause]

Hello, Jean Delmas
you wrote...

1 - VuescanScan with "Color | ICC profile" set to "Canon1220U.icc"
(ICC profile made with Vuescan)

2 - Vuescan with "Color|ICC profile" set to "Built-in"

3 - Scangear, regular Canon software

1-Vues-profiled 2-Vues-built-in 3-Scangear
Grey No 12 16 20 Bk 12 16 20 Bk 12 16 20 Bk
R 113 79 55 45 103 69 46 38 91 45 13 7
V 107 72 45 35 102 68 42 33 94 55 17 9
B 110 73 43 34 105 69 41 32 91 52 15 7

These measurements results are quite strange for a non-expert like me.
Main interesting conclusion is : red color cast is stronger on
"profiled" scanner than on "non-profiled scanner" !!

What is wrong ?

No Idea. But you did not mention what color balance you use in vuescan.
Please note that profiling is only useful with color balance neutral or
none.

Vuescan does no sophisticated IT8 profiling, it only adjusts gamma for
each color channel separately. If you want to eliminate color cast by
hand with your IT8 target (which is at least as good as vuescans
internal algorithm) you can do the following:

Preview your IT8 target. Right click on the white patch of the grey
scale (white point is set). Lock image color on the input tab. Adjust
black point manually to get true black for the black patch (something
like 15,15,15 is enough). Then adjust R and B brightness settings to
get a true grey for patch 12.

If you want to be exact, set Scan task to 'Make IT8 target' and set
Scan from File to the scanner IT8 data ("scanner.it8", if you renamed
the .txt file) supplied by Wolf Faust. Press preview and note down the
RGB values for the grey scale patches. Now try to use above mentioned
technique to adjust the scanned IT8 image to the desired values for
white, black and number 12 patch.

Note down all black and white point, color and brightness values from
the color tab and use them for subsequent scans.

If you want to make more sophisticated IT8 profiling, use lcms
profilers provided on http://www.littlecms.com/profilers.htm
Please note, that lcms profiles are only valid, if you use exactly the
same color balance and RGB exposure settings as you did for scanning
the target. lcms profiles must be applied in photoshop (or other icc
aware app) - vuescan can not read them, although it does not complain.

 

[Jean Delmas]

Hello Erik Krause, you wrote :

If you want to make more sophisticated IT8 profiling, use lcms
profilers provided on http://www.littlecms.com/profilers.htm
Please note, that lcms profiles are only valid, if you use exactly the
same color balance and RGB exposure settings as you did for scanning
the target. lcms profiles must be applied in photoshop (or other icc
aware app) - vuescan can not read them, although it does not complain.

Thanks a lot for your very interesting answer. I am going to follow
this workflow.
I only don't really understand what you mean by "vuescan can not read
them" (but, as you can see, my english is very french...). Do you mean
that Vuescan can only read icc files made with Vuescan ? I thought
that it was possible to set "Color|ICC profile" to any icc scanner
file made with any other scanner profiling software...

Jean Delmas

 

[Erik Krause]

Hello, Jean Delmas
you wrote...

I only don't really understand what you mean by "vuescan can not read
them" (but, as you can see, my english is very french...). Do you mean
that Vuescan can only read icc files made with Vuescan ?

Yes. All other programs I know produce more sophisticated profiles.

I thought
that it was possible to set "Color|ICC profile" to any icc scanner
file made with any other scanner profiling software...

No. Vuescan creates so called matrix profiles and is not able to read
3D-LUT- or TRC profiles, which are common types.
See the posting 'Re: Vue internal design (For Ed)'
Message ID <[email protected]> on this topic.

The posting from Wolf Faust <[email protected]> and
Ed's reply may be interesting, too.