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Author Topic: Scanner Profiling with it8 Target  (Read 1480 times)

nirpat89

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Re: Scanner Profiling with it8 Target
« Reply #20 on: May 14, 2017, 09:06:26 AM »

The other thing that can get you with older CCR tubes is adequate warm up time. Usually 20 minutes is enough. That could explain the shift between the two calibration runs.

If it is a replaceable lamp, you might be able to find a very high CRI equivalent replacement.
If i remember correctly, there is a calibration strip under the starting area of the glass that is used for internal calibration. i don't know of a replacement though if it has yellowed.

I do let it warm up for a good hour as well as run a long warm-up scan before I do the real scan. The 2 scans that I am showing are with and without applying the calibration profile.  They are not the same.  Successive scans are not drifting.  At this point I am going to make do with what I have.  Too many other issues to deal with.  Thanks for pointing to additional factors that I hadn't thought of.
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Ernst Dinkla

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Re: Scanner Profiling with it8 Target
« Reply #21 on: May 17, 2017, 06:42:21 AM »

The other thing that can get you with older CCR tubes is adequate warm up time. Usually 20 minutes is enough. That could explain the shift between the two calibration runs.

If it is a replaceable lamp, you might be able to find a very high CRI equivalent replacement.
If i remember correctly, there is a calibration strip under the starting area of the glass that is used for internal calibration. i don't know of a replacement though if it has yellowed.

That strip is between the glass and the top cover. To replace that in a way that it solves this issue will be hard. In fact that strip is well protected so I doubt it has to be replaced. If you are not using a fluid on the glass for wet mounting and it creeps in between the glass and the strip, like I did :-)  If the lamp has to be replaced, a copy with the same spectral output may be wiser, you never know how Epson compensated a lousy spectral output.  A good cleaning of the internal glass side was needed on more Epson scanners in time, dust and plasticizer condensation likely causes.

BTW try it too with the target lengthwise scanned and compare it to another direction target profile. The scanner calibration strip is not just setting one value for the strip width but should compensate irregularities over the width of the scan slit. Dust etc accumulated on the glass over the calibration strip spoils that calibration. Dust on the internal mirrors of the optical path to the lens remains the same along the scan path and is compensated in the calibration, dust on top and underneath the scan bed glass during the scan can not be calibrated for.

The lamp and your Wolf Faust target may have degraded in time, the last no longer representing the calibration numbers. AFAIK they were measured per batch and not individually per target. To be honest I have gone that way of scanner calibration more times with either the Wolf Faust iT8 or a CC Passport and it may result with better color for photo dye originals but any other dye or pigment type is not better reproduced. Wonder what the pigment in your monochrome contact prints is, not to mention the paper white. Vuescan probably does a good job for that right away. HP made good use of the flaws in two spectrally different CCFL lamps to nail color. That based on the metameric failure for each. Impossible with one CCFL lamp like in the 3200, the firmware/driver can only correct for a limited set of colorants then, usually the photo dyes.

Using a copy table + four 4000K halogens + a 5DII + the flat field plug-in for Lightroom to even out the lighting more and then creating a RAW color profile with the Passport in that set up is way more rewarding in my experience.

Met vriendelijke groet, Ernst

http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
March 2017 update, 750+ inkjet media white spectral plots



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nirpat89

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Re: Scanner Profiling with it8 Target
« Reply #22 on: May 19, 2017, 06:45:49 PM »

Ernst, thanks for the detailed response.

That strip is between the glass and the top cover. To replace that in a way that it solves this issue will be hard. In fact that strip is well protected so I doubt it has to be replaced. If you are not using a fluid on the glass for wet mounting and it creeps in between the glass and the strip, like I did :-)  If the lamp has to be replaced, a copy with the same spectral output may be wiser, you never know how Epson compensated a lousy spectral output.  A good cleaning of the internal glass side was needed on more Epson scanners in time, dust and plasticizer condensation likely causes.
I have no clue about the calibration strip.  There is no mention of it any of the scanner literature that I can access.  There are some mentions in the forum-land out there but from what I can tell people talk about it in the context of the transparency mode for film scanning which I am not using. 

Didn't use any liquids. After my doing the calibration for the first time and not liking the results, I did open the scanner up (something I would not dare repeat again) and cleaned the glass from inside that was visibly fogged due to years of out-gassing of stuff.  Post-cleaning calibration made no discernible difference.  So much for all the trouble!

BTW try it too with the target lengthwise scanned and compare it to another direction target profile. The scanner calibration strip is not just setting one value for the strip width but should compensate irregularities over the width of the scan slit. Dust etc accumulated on the glass over the calibration strip spoils that calibration. Dust on the internal mirrors of the optical path to the lens remains the same along the scan path and is compensated in the calibration, dust on top and underneath the scan bed glass during the scan can not be calibrated for.
I became aware of the directional variability while I was trying to use the scanner to create the correction curves for making digital negatives.  This is an another issue that I should probably leave it alone.

The lamp and your Wolf Faust target may have degraded in time, the last no longer representing the calibration numbers. AFAIK they were measured per batch and not individually per target. To be honest I have gone that way of scanner calibration more times with either the Wolf Faust iT8 or a CC Passport and it may result with better color for photo dye originals but any other dye or pigment type is not better reproduced. Wonder what the pigment in your monochrome contact prints is, not to mention the paper white. Vuescan probably does a good job for that right away. HP made good use of the flaws in two spectrally different CCFL lamps to nail color. That based on the metameric failure for each. Impossible with one CCFL lamp like in the 3200, the firmware/driver can only correct for a limited set of colorants then, usually the photo dyes.
The it8 target was purchased only about 6 months ago and not seen too much daylight since then.  No idea how old it actually is or how well matched the data set is to the target.  The prints I am trying to scan are gelatin silver on baryta paper.  Texture, reflectivity etc are obviously different from the target so it plays some role I guess.

Using a copy table + four 4000K halogens + a 5DII + the flat field plug-in for Lightroom to even out the lighting more and then creating a RAW color profile with the Passport in that set up is way more rewarding in my experience.

I actually had a similar set up (except the flat field plug-in, wish I knew there was such a thing) for an another project I was doing.  Unfortunately I dismantled it to make room for other things.  May be I will go back to it if this is not satisfactory.

For now I am going to scan without the calibration and fix any tonal discrepancy in PS.

Thanks again.

:Niranjan.
« Last Edit: May 23, 2017, 06:22:31 AM by nirpat89 »
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Ernst Dinkla

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Re: Scanner Profiling with it8 Target
« Reply #23 on: June 05, 2017, 04:36:18 AM »


I actually had a similar set up (except the flat field plug-in, wish I knew there was such a thing) for an another project I was doing.  Unfortunately I dismantled it to make room for other things.  May be I will go back to it if this is not satisfactory.


:Niranjan.

The Flat Field plug-in works well with Lightroom. There are suggestions that it should work with Camera Raw in Photoshop too but I never found a way to do that. Of alll the flat field/equalizers; Equalight - RawTherapee's version - etc, it was the easiest and best workflow despite the fact that I do not edit reproduction images in Lightroom and a conversion to DNG is needed. However last week I found the stand alone CornerFix and for my workflow it is even easier, the results similar. Still DNG conversions needed but in batch automation of DNG converter that goes fast, CornerFix has a batch function too.

You might solve your scanner color target issues with a flat field application too. Use a clean sheet of paper or rather more sheets on top of one another and create a scan near white clipping. Vuescan RAW export, it knows a DNG extension for export too. Not that both are real RAWs.  I  may have done that some years back but can not recall all the steps. Equalight works with Tiffs, I probably used that one. As written, I prefer a copy stand for more reasons.

Met vriendelijke groet, Ernst

http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
March 2017 update, 750+ inkjet media white spectral plots
« Last Edit: June 05, 2017, 04:52:18 AM by Ernst Dinkla »
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nirpat89

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Re: Scanner Profiling with it8 Target
« Reply #24 on: June 06, 2017, 07:57:54 PM »

The Flat Field plug-in works well with Lightroom. There are suggestions that it should work with Camera Raw in Photoshop too but I never found a way to do that. Of alll the flat field/equalizers; Equalight - RawTherapee's version - etc, it was the easiest and best workflow despite the fact that I do not edit reproduction images in Lightroom and a conversion to DNG is needed. However last week I found the stand alone CornerFix and for my workflow it is even easier, the results similar. Still DNG conversions needed but in batch automation of DNG converter that goes fast, CornerFix has a batch function too.

You might solve your scanner color target issues with a flat field application too. Use a clean sheet of paper or rather more sheets on top of one another and create a scan near white clipping. Vuescan RAW export, it knows a DNG extension for export too. Not that both are real RAWs.  I  may have done that some years back but can not recall all the steps. Equalight works with Tiffs, I probably used that one. As written, I prefer a copy stand for more reasons.

Met vriendelijke groet, Ernst

http://www.pigment-print.com/spectralplots/spectrumviz_1.htm
March 2017 update, 750+ inkjet media white spectral plots

Thanks, Ernst.  This CornerFix sounds interesting.  Will check it out.

:Niranjan.
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