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Author Topic: Silverfast Advanced Targets (ISO 12641-2)  (Read 1847 times)

na goodman

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Silverfast Advanced Targets (ISO 12641-2)
« on: March 05, 2022, 05:17:53 pm »

I'm helping a client calibrate an Epson 850 scanner. she does use Silverfast and we will be upgrading her software and wonder which target to order = the advanced or the standard iT8. I did read a previous thread but it was older and wondered if there was updated information. Thanks for any and all info, it is always greatly appreciated.
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Doug Gray

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Re: Silverfast Advanced Targets (ISO 12641-2)
« Reply #1 on: March 05, 2022, 06:29:31 pm »

I'm helping a client calibrate an Epson 850 scanner. she does use Silverfast and we will be upgrading her software and wonder which target to order = the advanced or the standard iT8. I did read a previous thread but it was older and wondered if there was updated information. Thanks for any and all info, it is always greatly appreciated.

It really depends on what sort of accuracy you need. The two major sources of intrinsic error on Epson 850's are metameric failure and large area glare. The former requires that the patch set print profiles are made from roughly match the media that one scans. There are major differences in the spectral response of the 850 between CYMK processes and chemical print processes. So ideally, one should use IT8 (or any "advanced" chart) that is made with the same process. Either CYMK or film chemistry. The latter is more similar to naturally existing colors and is closer to the spectral characteristics of natural pigments such as used in making ColorChecker cards. The former is better at scanning CYMK printed material including inkjet prints.

Large area glare is an intrinsic problem with the Epson 850 and most any reflection scanner but not drum scanners. It can produce really large errors and no chart types can fix it. See this for details, example of > 10dE errors, and software to fix it.

https://github.com/doug3236/scanner_refl_fix
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na goodman

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Re: Silverfast Advanced Targets (ISO 12641-2)
« Reply #2 on: March 05, 2022, 11:22:46 pm »

She's getting the blue/green cast so I was thinking profiling the scanner would help instead of manually correcting each scan. We're scanning old photos, film and negatives. The color cast is the worse with the old photos. I'm still not sure which target to purchase or after reading the link if it will make much of a difference to calibrate it at all.
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MichaelKoerner

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Re: Silverfast Advanced Targets (ISO 12641-2)
« Reply #3 on: March 06, 2022, 03:00:37 am »

Given the relatively small price difference of about 20 % between standard and advanced targets, you would want the advanced one.

But, as Doug explained, this does not mean you will get spot on colours after making a profile using it.

In my experience, a decent profile is a good starting point for scans, but manual adjustments stay required - especially when it comes to old pictures that need some amount of restoration.

Using a camera with a good macro lens on a repro stand (instead of the scanner) reduces the glare effect, but introduces problems with flatness and set up time.

YMMV :-)

na goodman

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Re: Silverfast Advanced Targets (ISO 12641-2)
« Reply #4 on: March 06, 2022, 08:48:49 am »

Thank you Micahael - I think we just have to lower our expectations but I think we'll still go ahead and calibrate/profile. I'll order the advanced target if we go that route. We really aren't experiencing the glare problem. Well, at least not yet. And thank you Doug for your thorough explanation.
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Doug Gray

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Re: Silverfast Advanced Targets (ISO 12641-2)
« Reply #5 on: March 06, 2022, 10:36:51 am »

In my experience, a decent profile is a good starting point for scans, but manual adjustments stay required - especially when it comes to old pictures that need some amount of restoration.

I strongly agree.

The glare issue only effects reflection scans, not film/slide scans. So it's the old photos that would be affected. Even there the effect visually is much less than the large deltaE variations suggest because of the human vision works. The color shifts that occur in old photos and metamer issues dominate. So yes, plan on manual adjustments. If you have groups of photos taken/printed in the same time frame you might get good results with a set of actions that implement a common set of adjustments. That's what I wound up doing with some old photos that dated back 2 to 4 decades.
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na goodman

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Re: Silverfast Advanced Targets (ISO 12641-2)
« Reply #6 on: March 06, 2022, 01:07:04 pm »

The old photos do date back decades. I'll look at applying an action for multiples. I meet with her tomorrow so we'll go over the upgrade in software and making the profile. Thanks again for the input.
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Alan Klein

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Re: Silverfast Advanced Targets (ISO 12641-2)
« Reply #7 on: April 18, 2022, 04:20:05 pm »

It really depends on what sort of accuracy you need. The two major sources of intrinsic error on Epson 850's are metameric failure and large area glare. The former requires that the patch set print profiles are made from roughly match the media that one scans. There are major differences in the spectral response of the 850 between CYMK processes and chemical print processes. So ideally, one should use IT8 (or any "advanced" chart) that is made with the same process. Either CYMK or film chemistry. The latter is more similar to naturally existing colors and is closer to the spectral characteristics of natural pigments such as used in making ColorChecker cards. The former is better at scanning CYMK printed material including inkjet prints.

Large area glare is an intrinsic problem with the Epson 850 and most any reflection scanner but not drum scanners. It can produce really large errors and no chart types can fix it. See this for details, example of > 10dE errors, and software to fix it.

https://github.com/doug3236/scanner_refl_fix

Doug I have the V850 but use Epsonscan with my Windows 10 computer.  I have scanned and loaded the included IT color charts but I don't know how to properly select it when scanning. 

What's the procedure if you know.  Tks.  Alan.

Here are the two that came with the V850: (corrected picture)
« Last Edit: April 18, 2022, 04:26:43 pm by Alan Klein »
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digitaldog

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Re: Silverfast Advanced Targets (ISO 12641-2)
« Reply #8 on: April 18, 2022, 04:47:20 pm »

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Doug Gray

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Re: Silverfast Advanced Targets (ISO 12641-2)
« Reply #9 on: April 18, 2022, 06:54:45 pm »

Doug I have the V850 but use Epsonscan with my Windows 10 computer.  I have scanned and loaded the included IT color charts but I don't know how to properly select it when scanning. 

What's the procedure if you know.  Tks.  Alan.

Here are the two that came with the V850: (corrected picture)

What media are you trying to scan? The V850 exhibits quite a bit of metameric failure with different media. CYMK printers tend to be pretty similar so for charts made with CYMK printers you can scan other CYMK printed material accurately. For other media like oil paintings it can introduce significant errors.

Basically, the chart used to create a profile needs to be similar material to the object being scanned for optimal results.
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Alan Klein

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Re: Silverfast Advanced Targets (ISO 12641-2)
« Reply #10 on: April 18, 2022, 07:20:33 pm »

What media are you trying to scan? The V850 exhibits quite a bit of metameric failure with different media. CYMK printers tend to be pretty similar so for charts made with CYMK printers you can scan other CYMK printed material accurately. For other media like oil paintings it can introduce significant errors.

Basically, the chart used to create a profile needs to be similar material to the object being scanned for optimal results.
Well, let's say I;m scanning Velvia 50 chromes and Ektar 100 negative color.  Do you use these color "charts" that were furnished with the V850 or something else?

digitaldog

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Re: Silverfast Advanced Targets (ISO 12641-2)
« Reply #11 on: April 18, 2022, 07:25:09 pm »

Well, let's say I;m scanning Velvia 50 chromes and Ektar 100 negative color. 
Then the targets you showed us are useless!
But you'd know that if again, you'd actually study the well-written manual for the software product you have. Like say, on page 439.  ;)
No such targets for any negs.....
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Doug Gray

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Re: Silverfast Advanced Targets (ISO 12641-2)
« Reply #12 on: April 18, 2022, 09:08:25 pm »

Well, let's say I;m scanning Velvia 50 chromes and Ektar 100 negative color.  Do you use these color "charts" that were furnished with the V850 or something else?

I scan mostly CYMK stuff. Often commercial printed material. Charts made with inkjets work great with these and produce highly accurate color providing large area glare is accounted for. See the link to the github program for fixing that. I don't use IT8 charts but rather charts with 2-3k patches from an inkjet (CYMK) measured with an i1isis. While great for CYMK scans, they are marginal for other material. I don't scan negatives.
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