Preview and final image dont match

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bsberlin
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Preview and final image dont match

Postby bsberlin » Wed Jan 02, 2008 9:02 pm

When scanning (Plustek 7200) colors of the preview image do not match the colors of the final scan in PhotoShop.

That makes color correction in Silverfast pretty useless. :cry:

Any idea what the problem is?

degrub
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Postby degrub » Thu Jan 03, 2008 12:42 am

pretty normal actually since the data sample used for calculating exposure etc goes up by a lot for most scans over the prescan. Can you do a "high detail prescan" ?

kalos
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Postby kalos » Sun Jan 20, 2008 11:06 pm

I have the same identical problem with my plustek 7500 also setting the prescan to be done at high quality.

This is really frustrating because I can not trust colors I see in the SF preview

degrub
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Postby degrub » Sun Jan 20, 2008 11:31 pm

the next thing to check is the CMS settings.

http://www.computer-darkroom.com/sf5-ne ... f5_cms.htm

so that SF is using the same colorspace that PS is.

kalos
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Postby kalos » Mon Jan 21, 2008 8:58 am

That's it... Thank you very much for the help!

Eagle
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Prescan/preview does not match final scan

Postby Eagle » Thu Feb 07, 2008 6:11 pm

On the Plustek 7200i product, when I do a preview/prescan and then a final scan, all is well if my chosen resolution is 3600dpi or below (I have followed the CMS setting recommendations). BUT, if I select the 7200dpi resolution, then the preview and final scan never match. When I go back to 3600dpi, the preview and final match again.

This is perfectly consistent so it seems to be a bug somewhere in Silverfast and how it works with the 7200i.

degrub
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Postby degrub » Fri Feb 08, 2008 1:41 am

Start by deleting the prefs files and reboot, see if that changes anything.

If not, please submit a bug report.

Eagle
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Postby Eagle » Sat Feb 09, 2008 1:13 am

I went through this procedure already with no success. I have also tried different versions (6.4xx). I previously submitted a bug report (about a month ago) and was told by the service technician not to use 7200dpi because this scanner performs pooly at high resolution (poor clarity at this high dpi). Not a very professional solution to the problem it seems to me.

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Postby LSI_Noack » Fri Feb 22, 2008 4:41 pm

Dear bsberlin

while I see plenty of reason a professional approach might be to use efficient and effective settings, I fail to see how the scan resolution of 7200 DPI should give you discoulored final scans.

Can it be that the difference you were perceiving having to do with scanner lamp not being warmed up long enough, i.e. prescan had been done "fresh" on a given scan session, but of course subsequently performed final scan then been long enough to warm up the lamp, but changing the lamp's light quality?

Best regards
Sonny Noack
- Manager Technical Support, LaserSoft Imaging AG -

Eagle
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Postby Eagle » Wed Feb 27, 2008 8:16 pm

Interesting theory, but not applicable. When I found this problem I scanned at 7200dpi, then 3600dpi, then 7200dpi and back to 3600dpi to assure that the only thing changed between scans was the resolution setting. Each scan was done immedialely after the previous one. I've done this test several independent times with the same result. 7200dpi always produces the same (too bright) mismatch (on negatives I should mention, I don't recall my test results with slides). Using v**s**n does not produce this problem, but I prefer to use SilverFast.

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Postby LSI_Noack » Thu Feb 28, 2008 10:28 am

Dear Eagle

thank you very much for your follow-up and your efforts in reexaming the phenomenon. I will let the issue being tested internally and post our findings as soon as possible...

Best regards
Sonny Noack
- Manager Technical Support, LaserSoft Imaging AG -

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Postby LSI_Noack » Fri Apr 04, 2008 9:19 am

Dear Eagle

after extensive testing we can conclude that e.g.
(1) turn scanner on
(2) scan in 3600 dpi
(3) scan in 7200 dpi
will result in a much lighter image for the 7200 dpi; also
(1) turn scanner on
(2) scan in 7200 dpi
(3) scan in 3600 dpi
will result in a lighter image for the 3600 dpi scan; even
(2) scan in 7200 dpi
(3) scan in 7200 dpi
will have scan from step no. 3 be lighter.

The problem is the warming up of the scanner. Please note that Plustek offers a patch for downloading on their website that addresses a warming up issue. Is this will fix the problem here, I cannot say because we don't have tested it yet.

However, if the scanner had been warmed up sufficiently, we cannot reproduce colour deviances greater a value of two (on a 0-255) scale, which I deem okay when keeping in mind that we're considering negatives here (and of what end consumer market is targeted with that scanner).

Best regards
Sonny Noack
Director Support & Software Testing
Master-Making
- LaserSoft Imaging AG -


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