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Input/Output/Workflow Scanning, printing, color management, and discussing best practices for control and repeatability

scanner banding

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  #1  
Old 02-06-2003, 10:18 PM
christo christo is offline
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scanner banding

Sometimes, not always, but sometimes I seem to get a sort of banding effect when I scan in photographs, particularly where the photograph has a dark area right at the bottom edges of the photo. There is a cloud like effect right next to the flag. If you zoom in and move to the right you can see the banding. Any ideas on what is causing this and better yet how to get rid of it?
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Old 02-07-2003, 05:21 AM
Stephen M Stephen M is offline
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Christo, can you crop out the high res section (say 100x100 pixels at the true scan resolution) and repost, or in the high res file zoom in and do a screen capture?

I have not looked at the file, but at the small size you posted makes good evaluation and answers somewhat hard.

Are you scanning the glass or other area around the photo too, or do you use scan software to crop into the image when scanning (better).

Ensure the originals are clean of finger oil and other marks in the shadows (scanner glass too).

Stephen Marsh.
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Old 02-07-2003, 09:26 PM
christo christo is offline
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Stephan,
Here is the most troublesome area
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Old 02-07-2003, 09:48 PM
Stephen M Stephen M is offline
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What is the ghosted fogging?

Why are the tram tacks in the fogging?

Is this a reflective or transmissive scan?

Is this a faltbed or a film scanner?

Are there tram tacks in other areas without ghosting?

As mentioned before, are you cropping into the media when scanning or including scanner glass too?

Does placing the scan in another area of the flatbed provide different results (with the media in the same direction)?

Does placing the original ninety degrees offset to the original scan change things?

What is the difference between what you do with this scan and with scans that come out OK?

Sounds like I missed my calling and should have been on scanner tech support. <g>

Stephen Marsh.
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Old 02-07-2003, 11:39 PM
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roger_ele roger_ele is offline
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Just a note

There is a separate strip of glass about 1/2 inch by the width of my scanner. The sacanner uses this strip to internally calibrate itself. ANY dust on it and where that dust is will show up as a line throughout the scan - so make sure that strip is VERY clean. That fixed the problems that I had that looked very similar to this.

Hope this helps, Roger
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Old 02-08-2003, 09:35 PM
christo christo is offline
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Stephan,
What is the ghosted fogging?
I don’t know, that is part of the problem

Why are the tram tacks in the fogging?
Not sure what you mean on this one.

Is this a reflective or transmissive scan?
Reflective

Is this a faltbed or a film scanner?
Flatbed MicroTek V6 USL

Are there tram tacks in other areas without ghosting?
Tram tracks?

As mentioned before, are you cropping into the media when scanning or including
scanner glass too?
No cropping at all.

Does placing the scan in another area of the flatbed provide different results (with the
media in the same direction)?
I haven’t tried that

Does placing the original ninety degrees offset to the original scan change things?
Haven’t tried this one either

What is the difference between what you do with this scan and with scans that come out
Usually I try and scan it on another machine.

Rodger,

I don’t see any other glass strip, other than the scanning surface glass. I do clean that regularly.
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Old 02-08-2003, 10:50 PM
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roger_ele roger_ele is offline
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Just a suggestion, ask MicroTek what this scanner uses to calibrate, and if there is any dust there what kind of problems it would cause.

Look from a very low angle with the scanner lights on and the lid off. You might be using something that steaks the glass and isn't seen with the eyes, also the underside of the glass can develope a film residue ...

On my Agfa scanner the calibration strip is a seperate strip of glass at the front end of the transparency tray. On my Epson it is at the back end on the scanning bed, also a seperate strip of glass about a half inch wide, parallel to the hinge. Your Microtek might have a different system than gless for calibration, but it seems that they all have some sort of system. I looked on the Microtek site and the FAQ section sent me to a scanning tips page, where they mentioned to be careful cleanning around the rulers because some scanners use this area for calibration ...

Good luck, Roger
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Old 02-09-2003, 10:18 AM
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KevinBE KevinBE is offline
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Hi Christo, I just have a couple of thoughts. What resolution are you using for this scan? Is it possible you are exceeding the optical resolution of the scanner? The optical resolution is usually the first number stated in the scanner resolution capabilities, IE 1200 X 2400 resolution actually means the optical resolution is 1200 DPI. Scanning above this number will result in the scanner interpolating the image to get the scan data. I have seen this happen on my Epson 1240U scanner.

Second, you might try to scan with the lid up or place a dark black piece of paper to cover the white lid underside. Sometimes the shiny white lid cover will reflect ligth back down to the subject.

Just a thought.
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