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Scanning to reduce surface texture or silvering

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  #1  
Old 08-24-2003, 11:11 PM
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Post Scanning to reduce surface texture or silvering

A method of scanning to reduce the haze found when scanning photos of texture or silvering (a metalic coating most easily seen in the dark areas of some old photographs). I Used Photoshop 7 although this should apply to any version and probably some other image editing programs. [details]
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Old 08-25-2003, 10:15 AM
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Excellent tutorial Roger. This seems to be a common problem, and the reason your tutorial is excellent is because you not only told how to cope with the problem, but why it works. Good job.

Ed
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Old 08-25-2003, 10:41 AM
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THANKS Roger!!

Jeanie
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Old 08-25-2003, 10:48 AM
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Doug Nelson Doug Nelson is offline
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Our first member-submitted tutorial on our new system, and an excellent one at that! Thanks, Roger.

Maybe this will serve two purposes: teaching an excellent way to beat silvering, and inspiring other members to submit tutorials of their own.

C'mon guys! Show us your stuff!
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Old 08-25-2003, 01:29 PM
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Roger,

Excellent work, as always. This will help many people to start with the best possible image before attempting any retouch/restoration work.
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Old 01-22-2006, 02:23 AM
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Scanner mechanical non-linearity

[ I found this old thread searching for ways to cope with the haze of microscopic scratches on a print ]

My Microtek i800 seems to have two lamps; I theorized that rotating the print 180 degrees would have essentially no benefit, so I attempted this technique with a 90-degree rotation, scanning a 2.5" x 3.25" print at 1200dpi for the test.

The upshot is that the spatial precision of the scanner seemed to be poor enough that it didn't work very well. I could see in the "difference" view of the layers that there was more than just x/y and theta (angular) alignment to consider.

I made another test with an artifact from a previous job that turns out to be nearly perfect for this sort of test. It's a 6" diameter ceramic wafer with a pattern of about 6,000 millimeter-sized devices "printed" on it with what are essentially $500,000 (US) enlargers , at incredible precision. (It's a "thin-film" wafer of magnetic disk-drive heads). This item I scanned at 1000 dpi.

Over an area of about 3" x 5", I discovered that the 90-degree layer was 0.7% narrower and 0.7% taller than the 0-degree layer, and that I also had to dial in 0.2 degrees of vertical skew in the Photoshop Free Transform tool to make the corners line up. And then the bad part: the "y" direction of the scan is non-linear, presumably due to errors in the stepper motor/belt/encoder mechanism. The registration was off by as much as eight pixels in some areas, but varies across the length of the scan to produce a regular interference pattern.

I've only done these two tests so far; I'll probably try again with some of the 70's-era textured prints my family has. Those features are so much larger that they might have a chance. But for these micro-scratches I'm re-evaluating how valuable these actual prints are vs. their images (They're at least second-generation copies); I'm looking into tricks like wetting the print with water or glycerine to scan them.
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Old 01-22-2006, 09:42 AM
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Hi DaveToo,

Welcome to RP!

Thank you so much for sharing your experiences and results!!!!

It's a problem we all have so, please, let us know if you get better results and how ...
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Old 03-05-2006, 02:02 PM
mosquito mosquito is offline
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Quote:
Originally Posted by roger_ele
A method of scanning to reduce the haze found when scanning photos of texture or silvering (a metalic coating most easily seen in the dark areas of some old photographs). I Used Photoshop 7 although this should apply to any version and probably some other image editing programs. [details]

hello
i have a scanner CANON 8400 F and i tried your method but with no results. what scanner have you used - any special settings ?

thanks.
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