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Author Topic: How to calibrate a scanner  (Read 10189 times)

Bas Stekelenburg

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How to calibrate a scanner
« on: February 19, 2009, 11:12:07 AM »

Dear friends and colleagues,
I have an older flatbed scanner, the Epson Expression 1600 Pro. After years of successful work, I just replaced the lamp.
Native resolution 1600 x 3200 dpi, 36 bit color depth and 3.3 Dmax is not (longer) state of the art, but for all but 135 mm film scans good enough. Only original (updated) Epson software, no Silverfast.
It is my only non-calibrated device. I am very happy with the HP LP2475w monitor and the HP Z3200 24”printer, all calibrated and profiled by itself (printer) or by means of the Spyder 3 (monitor).
I have no densitometer. I do have a Xrite ColorChecker card.

Could you please advise me if and how I will be able to calibrate this Epson scanner?
Bas
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Czornyj

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How to calibrate a scanner
« Reply #1 on: February 19, 2009, 04:46:16 PM »

Quote from: HasselBas
Dear friends and colleagues,
I have an older flatbed scanner, the Epson Expression 1600 Pro. After years of successful work, I just replaced the lamp.
Native resolution 1600 x 3200 dpi, 36 bit color depth and 3.3 Dmax is not (longer) state of the art, but for all but 135 mm film scans good enough. Only original (updated) Epson software, no Silverfast.
It is my only non-calibrated device. I am very happy with the HP LP2475w monitor and the HP Z3200 24”printer, all calibrated and profiled by itself (printer) or by means of the Spyder 3 (monitor).
I have no densitometer. I do have a Xrite ColorChecker card.

Could you please advise me if and how I will be able to calibrate this Epson scanner?
Bas

You can't calibrate it, but you can profile it. All you need is a scanner target, and some profiling software. There are 2 kinds of targets - standard IT 8.7/1 target, and individually measured HCT target. In case you don't have any commercial profiling software, you can use open source Argyll CMS.

Bas Stekelenburg

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« Reply #2 on: February 21, 2009, 06:41:50 AM »

Quote from: Czornyj
You can't calibrate it, but you can profile it. All you need is a scanner target, and some profiling software. There are 2 kinds of targets - standard IT 8.7/1 target, and individually measured HCT target. In case you don't have any commercial profiling software, you can use open source Argyll CMS.

Thank you; I'm not aware of any of the targets or software you mentioned.
So the Xrite Colorchecker card is not much of a help?

Is it not needed to calibrate first and profile afterwards, to establish the scanner-computer-screen connection?

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PeterAit

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« Reply #3 on: February 21, 2009, 12:15:52 PM »

Quote from: HasselBas
Thank you; I'm not aware of any of the targets or software you mentioned.
So the Xrite Colorchecker card is not much of a help?

Is it not needed to calibrate first and profile afterwards, to establish the scanner-computer-screen connection?

No - as I understand it (and I hope someone will correct me if needed), profiling the scanner means that a target is accurately converted to the device-independent color space of the resulting file (for example, Adobe RGB). Then, assuming your monitor is also profiled, it will accurately display those colors as represented in the file. So, the scanner and monitor both need to be profiled, but they are totally separate from each other.

Peter
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Gupfold

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How to calibrate a scanner
« Reply #4 on: February 27, 2009, 08:49:53 AM »

I have had very good success using the AIM profiler http://www.aim-dtp.net/index.htm to make scanner profiles for the Epson 3200 and V700 with a Kodak 5x7 target and I have also used a silverfast target, I found them to be more accurate than using silverfasts profling, takes longer but the results are good.
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mcmorrison

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« Reply #5 on: February 28, 2009, 03:29:47 PM »

Hello,

I have recently had very good luck profiling an Epson 10000XL using a Gretag Color Checker SG. I scanned it, cleaned up the scan, and emailed the scan to Scott Martin at Onsight. He made me a profile that has been outstanding. I used VueScan, and scanned in raw mode, 48-bit.

Best,

Michael Morrison
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digitaldog

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« Reply #6 on: February 28, 2009, 04:22:39 PM »

What's necessary is having a target that has the gamut limitations of what you're trying to capture. IT8's (and HCT) are made of transparency film or a reflective print because that's what we're going to scan. The target also has to have a document that defines the color of the patches in something like LAB so the profiling software can compare the reference data to the measured (scanned) data. The supported software has to 'understand' what to do with the reference data and the scanned data to build the profile. So no, the Macbeth isn't going to cut it.
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Andrew Rodney
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mcmorrison

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« Reply #7 on: March 01, 2009, 11:40:55 AM »

Hello,

The Color Checker SG has, as I understand it, a published LAB reference file—which was used to make the profile. In any event, this approach only works for reflective scans. While there may be some subtleties that this approach misses, the profile made this way is now performing superbly in day to day use. To date, it is the best profile I have had for my 10000XL, and if it has shortcomings they have not shown up so far. The gamut of the CCSG encompasses that of all the scans I have made with it.

Best,

Michael Morrison
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Scott Martin

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« Reply #8 on: March 02, 2009, 10:09:19 AM »

Quote from: digitaldog
IT8's (and HCT) are made of transparency film or a reflective print because that's what we're going to scan.
I've found the HCT targets to be the way to go for transmissive film scanning. Reflective scanning, however, goes well beyond silver halide print scanning. Mike and others involved in fine art reproduction are scanning a wide range of artwork with colors that far exceed what silver halide is capable of.

Quote from: digitaldog
The target also has to have a document that defines the color of the patches in something like LAB so the profiling software can compare the reference data to the measured (scanned) data. The supported software has to 'understand' what to do with the reference data and the scanned data to build the profile.
but every major profiling software comes with reference data for the ColorChecker SG....

Quote from: digitaldog
So no, the Macbeth isn't going to cut it.
I've performed exhaustive testing with Cruse and other scanners for very demanding reproduction shops. For reflective profiling I've made profiles with just about every major profiling software and combination of targets. Through this kind of exhaustive, real-world testing, I've found that the ColorCheckerSG not only cuts it, it cuts it really well. Reflective profiles made with the ColorCheckerSG and the right software go a long way toward allowing people to scan and make impressively well matched reproductions with a minimal amount of adjustments.

HasselBas, when scanning a profiling target with the Epson software you'll need to choose Configuration>Color>NoColorManagement and scan the target with no adjustments. Once you've got your profile you can enable it as the scanners profile in the same dialog. Choose your preferred working space for the target space and check the display compensation button so that your display profile is used to correctly display scans onscreen. While I'd recommend the HCT target for transmissive scanning and the ColorCheckerSG for reflective scanning, I recognize that for some the expense and hassle of getting an HCT transmissive target is overkill and I've been surprised at how well a good reflective profile works for transmissive scans on Epson hardware/Epson software systems. As always, let tests speak for themselves and do what you feel is best for your needs.

digitaldog

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« Reply #9 on: March 02, 2009, 10:14:09 AM »

Quote from: Onsight
Reflective scanning, however, goes well beyond silver halide print scanning. Mike and others involved in fine art reproduction are scanning a wide range of artwork with colors that far exceed what silver halide is capable of.

Who's Mike? As far as scanning something other than film, I'd agree. Did I miss something about scanning non silver halide prints?
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Andrew Rodney
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Scott Martin

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« Reply #10 on: March 02, 2009, 10:39:21 AM »

Quote from: digitaldog
Who's Mike? As far as scanning something other than film, I'd agree. Did I miss something about scanning non silver halide prints?
I was just quoting from your apparent response to Michael Morrison (Mike) who uses the ColorCheckerSG or "Macbeth" (as you referred to it) for Epson scanner profiling. Perhaps I misunderstood you - what did you mean by "the Macbeth isn't going to cut it"? Perhaps some more specificity is in order.

As long as we're hammering out the specifics we should say that the original 24 patch ColorChecker (which is perhaps what you have HasselBas) doesn't produce very good scanner profiles largely due to it's weak black. The ColorCheckerSG (semigloss) was designed to be an improvement of the original and works far better for camera and scanner profiling.

digitaldog

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« Reply #11 on: March 02, 2009, 11:47:41 AM »

Quote from: Onsight
I was just quoting from your apparent response to Michael Morrison (Mike) who uses the ColorCheckerSG or "Macbeth" (as you referred to it) for Epson scanner profiling. Perhaps I misunderstood you - what did you mean by "the Macbeth isn't going to cut it"? Perhaps some more specificity is in order.

Got it now. The Macbeth I was referring to was the 24 patch. I can see how the SG would be better, better still the original glossier DC camera target assuming reflections are not an issue as they so commonly are when shooting one.

Quote
As long as we're hammering out the specifics we should say that the original 24 patch ColorChecker (which is perhaps what you have HasselBas) doesn't produce very good scanner profiles largely due to it's weak black. The ColorCheckerSG (semigloss) was designed to be an improvement of the original and works far better for camera and scanner profiling.

Depends on your opinion of improvement. My understanding is, the original was fine and had a wider gamut due to the gloss patches, but those gloss patches produced awful profiles if there were any reflections captured within these patches. That made "casual" capture far more difficult. If I thought I needed to build an ICC profile for my Canon 5DmII, and had a Raw converter I wanted to use it in, I'd setup a studio strobe and copywork-like setup and shoot the DC. Then I'd use that profile in the identical setup.

Adding your own patches that reflect the object in the scene would be preferable still.
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Andrew Rodney
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Scott Martin

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« Reply #12 on: March 02, 2009, 12:08:04 PM »

Quote from: digitaldog
The Macbeth I was referring to was the 24 patch. I can see how the SG would be better, better still the original glossier DC camera target assuming reflections are not an issue as they so commonly are when shooting one.
PMP and MP both come with reference files for all three ColorCheckers - let's refer to them as CC, CCDC and CCSG. Profiles made from the CC are unacceptable. The profiles I've made form the CCDC have been decent yet disappointing even when reflections were controlled. It's the CCSG that really shines for profiling both cameras and scanners. I wasted a lot of time on the CCDC when it came out and my contacts at XRite admitted there were issues and sent me a complementary CCSG when it came out, apologizing for the shortcomings of the CCDC. With the CCSG I don't see a need to keep the CC or CCDC around any longer. I think they've finally gotten it right!

Gupfold

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« Reply #13 on: March 02, 2009, 01:31:53 PM »

Quote from: Onsight
It's the CCSG that really shines for profiling both cameras and scanners.

Do you think the CCSG would be a better target than the 5x7 Kodak or even the Silverfast target which both have many more patches? What software would you recommend for making the profile with this target?
« Last Edit: March 02, 2009, 01:35:27 PM by Gupfold »
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Scott Martin

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« Reply #14 on: March 02, 2009, 02:13:48 PM »

Quote from: Gupfold
Do you think the CCSG would be a better target than the 5x7 Kodak or even the Silverfast target which both have many more patches? What software would you recommend for making the profile with this target?
For reflective scanning with the Epson Scan software? Yes. ProfileMakerPro's scanner module.

Gupfold

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« Reply #15 on: March 04, 2009, 01:23:17 AM »

I scan water colour and acrylic paintings that need to be as true in colour to the original as possible. Would CCSG target and profile maker still be the right thing, is there other software like the AIM profiler out there that compares to the Profilemakerpro?
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keithrsmith

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« Reply #16 on: March 04, 2009, 04:00:16 AM »

It may be worth mentioning that with the I1 Photo you can print out a chart, measure it with the spectro and then scan it to profile the scanner.  Works fine for reflective, but no good of course for transparancy

Keith
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neil snape

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« Reply #17 on: March 04, 2009, 05:07:41 AM »

The OP said he wanted to know if he could calibrate for film.

Well you can profile the system including whatever software is used for positive films both transparent and reflective. You cannot profile colour negative films.
You have to be careful that no automatic corrections are taking place in the Epson scan soft.  You have to lock down the controls to the same set up each time. You then need to scan and profile a chart be it a reflective IT8 or transparent IT8. There are other charts but they will cost more than the scanner is worth.

I use Kodak charts, Wolf Faust charts, and HCT charts. I don't have a clue as to why I still hang onto them though as I don't scan film any longer.

As to using a MacBeth chart> the idea of a MacBeth chart is the pigments chosen in making the charts are the pigments could represent naturally occuring elements in a photo. They are not at all the same thing as film dyes. If you are scanning film then use charts made on the film or as close as you can,. If you are scanning other than film then sure use a MacBeth chart as a best guess.

If you can borrow a chart from someone , just send the scanned chart to someone with the software to make a profile.
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