Scanner Calibration - but it's not MY scanner

[Stephen G]

Greetings from windy Cape Town.

Following on from this thread: [a href=\'index.php?showtopic=32226\']How to calibrate a scanner[/a]

I occasionally assist artists in setting up their work for short run prints. I usually just tell them to pick a scan service that’s convenient to them and then deal with whatever image lands on my desk. We don’t really have a pro scanning service in town. There is a Cruse scanner in town, however, and I pushed a few artists towards it to see what results they got. Mixed, was the answer. The operators don’t appear to have profiled the scanner and have limited knowledge of colour management. Sometimes supply in Adobe RGB, sometimes a CMYK space, and once the scanner’s own canned profile (the latter producing best results to date). They do have a ColourChecker SG, however, and I thought perhaps I could take advantage of this.

What I'd appreciate comment on is this: I ask them to scan the CCSG, and then create a profile that I’d simply assign to any scans that come from them. I think the basic idea is sound but I’m a bit gappy on the workflow. What specs should I ask them to scan it with? What profiling software to use? Is assigning the created profile to the supplied scans correct?

[Scott Martin]

I guess this question quite often from artists and I think it's funny that they are the ones helping big shops get their Cruse scanners profiled.

On the Cruse the first thing to do is to determine the optimal exposure. As a customer you may have to assume that they've already done this and proceed with profiling it. You can have them scan a CCSG, Hutchcolor Target or whathaveyou at a fairly low resolution. 150ppi at 100% is plenty for profiling purposes. Ask them to supply you with the unadulterated scan without any colorspace conversions or adjustments (this is important)! If it comes tagged with their custom cruse profile that's OK - you'll ignore that for profiling purposes. I have found that I get the best results making a scanner profile in ProfileMakerPro using the " Paper Colored Gray" and "LightBoxGTI D50" settings.

I'd suggest having the profiling target scanned with a piece of artwork that's challenging to reproduce. With this combined scan, you can test your new profile by assigning it to the scan and printing from this. If the future, plan on assigning your new profile to unadulterated scans from the Cruse and immediately convert them to your working space of choice before performing color adjustments and retouching. The scanner profile may not be perfectly gray balanced or well behaved so your color adjustments tool will perform best when your scans are in a working space.

If your Cruse operators are up to the task, they could consider adopting your new profile as the default in the Cruse software and could be encouraged to convert all of their scans to a working space (like AdobeRGB or ProPhotoRGB) before delivering files to their customers. That's essentially what the best Cruse scan providers do for their customers.

As always, test throughly when evaluating new profiles and proceed with caution. Make sense?

[Stephen G]

All makes sense, can't thank you enough!

Only one thing: I've never tested a scan profile before. Apart from applying it to supplied scans, printing them and eyeballing them are there any other, more rigorous ways of testing?

[teddillard]

Greetings from windy Cape Town.

Following on from this thread: [a href=\'index.php?showtopic=32226\']How to calibrate a scanner[/a]

I occasionally assist artists in setting up their work for short run prints. I usually just tell them to pick a scan service that’s convenient to them and then deal with whatever image lands on my desk. We don’t really have a pro scanning service in town. There is a Cruse scanner in town, however, and I pushed a few artists towards it to see what results they got. Mixed, was the answer. The operators don’t appear to have profiled the scanner and have limited knowledge of colour management. Sometimes supply in Adobe RGB, sometimes a CMYK space, and once the scanner’s own canned profile (the latter producing best results to date). They do have a ColourChecker SG, however, and I thought perhaps I could take advantage of this.

What I'd appreciate comment on is this: I ask them to scan the CCSG, and then create a profile that I’d simply assign to any scans that come from them. I think the basic idea is sound but I’m a bit gappy on the workflow. What specs should I ask them to scan it with? What profiling software to use? Is assigning the created profile to the supplied scans correct?

hmmmm.  I'm a little confused, but that's not unusual.      I've been working on the Cruse for a few months now, here in Boston (at Parrot Digigraphic) and we use a pretty simple workflow.  The scanner software has it's own calibration procedure where it essentially builds it's profile, there's no external profiling going on.  We set up the parameters of that profile- white point, black point, like that, and then either deliver the raw scans in the scanner's profile, or we convert to AdobeRGB 1998, depending on what the client wants, or, what they know.  If it's going to an artist, I'd typically drop it down to 8-bit Adobe RGB.  If it's going to a giclee print service, I give them the raw scan and let them convert.  

What we look for in QC is that we're holding the highlight detail, the shadows, like that- pretty typical scanner protocol.  On the Cruse, however, you can control the light source- direction, balance, etc, to optimize the original detail (and each instance needs its own profile, btw).  For a little demo of the thing, take a look at the quick video we put together: http://www.youtube.com/watch?v=3On7KXANVX0

Unfortch, to me, it sounds like the guys running the Cruse near you aren't really being too pro-active about finding out what their clients need, and making sure they get it...  We consider that to be our responsibility, you shouldn't have to worry about making sure the scan is color managed, IMO.