[Techtalk] getting quality photo scans

[mk_hayes at charter.net]

Hi Carla, 

I'm an amateur photographer, so I actually feel confident in offering advice on this.  The best quality scans can only be had by scanning negatives.  So if you have access to those, you should scan them instead of the prints.  You can pick up a Minolta DiMage IV for cheap money, and get really fine scans.  If you have a mix of prints and negs, (and can drop some dough)  the Epson V700 gets fantastic reviews.  It can get the same quality film scans as an entry level dedicated film scanner, like the Minolta.  But at five times the price, I should hope so.  If you can only scan prints, check the reviews at photography websites, but my advice is to get the best Epson you can afford.  

No matter what you scan, there will be a lose of sharpness.  This is just an inevitable result of digitizing.  (True for digital cameras as well.)  Unsharp mask is your friend, stay away from sharpen.  One thing to keep in mind when looking at high rez photos on the monitor is don't judge sharpness by looking at images zoomed to 100%.  25% is recommended.  It's a good rule of thumb, but is somewhat resolution dependent.  

Color is a problem.  I hear that the Gimp is adding support for ICC profiles.  This would be helpful if you are going to scan, then print with a properly profiled scanner and printer with no color adjustments.  Of course, what you see on the monitor will likely be completely different.  I've been keeping my ears open, but I haven't heard anything about monitor calibration under linux.   Until someone comes up with something at least as good as the extremely lame eyeball calibration of Adobe Gamma, photography under linux will continue to be an exercise in frustration.  At least if you care about color.

If you are not planning to ever print what you're scanning, but say  putting photos on the web for other family members to enjoy, then color calibration is largely irrelevant.  Unless those viewing the photos are photographers with calibrated monitors, you can only guess what colors they're going to see.  To give yourself a better sense of the color quality of your scans, you'll probably need to turn the brightness of your monitor way down and also lower the color temperature.  When switching from linux to Windows (calibrated), my monitor gets darker and more yellow.  And if I go from my laptop (set for general use comfort) to my desktop, both under linux, I get the same effect, darker and yellow.  Switching from linux laptop to Win desktop is shocking. 

Some people don't notice the color problem (or much sharpness either.) It's like having an ear for music.  Some are born with perfect pitch, most get better ears with more training and practice, some are tone deaf all their lives.  Photography is the same way.  The more you do, the more you see.  

No matter what scanner you get, getting good scans takes practice.   When I scan, I turn off all auto adjustment, and set exposure using histograms.  I leave all levels and curves adjustments to photoshop.  I do multipass scanning because it reduces noise and brings out a bit more detail.  But it takes more time and processor power.  My philosophy is to get the most data I can with the highest signal to noise ratio possible, then tweak in my photo editor of choice.

Good luck
MK 

---- Carla Schroder <carla at bratgrrl.com> w rote: 
> On Thursday 16 November 2006 21:07, Akkana Peck wrote:
> > Carla Schroder writes:
> > > That's interesting, because even when I run a scan at the highest
> > > resolution, which is supposedly 1200x2400, it takes longer and it
> > > produces a much larger file. But to my eye it looks exactly the same as
> > > lower-res images. I think I
> >
> > Is that the highest optical resolution, or the highest interpolated
> > resolution? Some scanners offer fake resolutions that are a lot
> > higher than their sensors can scan. If the interpolation software
> > isn't that good, you might do better scanning at low resolution
> > then scaling it up in gimp or imagemagick.
> >
> > But I doubt that's the real cause of the sharpness problem
> > you're seeing -- any modern scanner should have plenty of optical
> > resolution (300dpi is usually plenty) to give a nice sharp scan
> > of any normal sized photo.  So there's probably something else wrong.
> >
> > Do you know if the scanner is capable of making decent images at
> > all (e.g. with a windows or mac driver)? I know I always hear that
> > multifunction devices don't scan very well, but I'm not clear whether
> > that's all a Linux problem or if they just aren't very good scanners.
> 
> Well now there's a funny story behind that. When I first got the device I 
> installed the Windoze drivers and tried to use it with Windows XP. The 
> bundled software was absolute poo- it brought a Sempron 2800 with 512 
> megabytes ram to its knees. The interfaces were beyond sucky and well into 
> random, to the point that both Terry and I had permanent ??? hovering over 
> our heads.
> 
> After a few days of struggle, I figured I could either try purchasing some 
> good winderz apps, or try it on Linux. Why did I not try it on Linux first? 
> Because I am a doofus with blind spots. The only hitch was entering the 
> scanner into udev so that ordinary users could use it. After that it was easy 
> peasey, and I've done loads of scanning and digital editing on Linux ever 
> since.
> 
> Anyway the scans are no better in Windows. So I'm starting to think it's the 
> scanner itself. It's a cheap piece of poo anyway, it won't break my heart to 
> go shopping for a better one.
> 
> -- 
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Carla Schroder
> Linux geek and random computer tamer
> check out my Linux Cookbook! best
> book for sysadmins and power users
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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