Scanning Issue With Unwanted Object On Scans, How To Avoid?

On some of my cover scans a small rectangle of black and white squares appears on the top edge of the scan about two inches from the left edge and I cannot get rid of it.

It does not appear on all scans, so I think it has to do with the enhancements I use for the scan.

I am using a HP 2600 series scanner with the Smart Scan software.

What is this, why does it appear on the scan, and how can I avoid it?

An example is posted below:

DonSellos

It appears to be a moiré pattern that is being introduced by the software. To prevent, try scanning at a different resolution. If it occurs at one resolution but not at another resolution, then you have verified that it is an moiré issue with the software.
Don

Interesting, never seen that before.
50,000 scans.
My "moire" pattern, appears occasionally as a red or blue or yellow stripe, albeit very rarely.

i have a canon and using a mac. maybe try scanning as a .pdf then convert to .jpg... Its easy for me to do that. Also I saw some things on the net to use photoshop if you have it - to remove the moire.

Thanks to all for the information. I'll re-scan the cover using the suggestions offered and see what happens. Will report back later.

DonSellos

Could it be position-related? Have you tried scanning at a different position on the scanner? Or... does the pattern (when it DOES repeat) appear at the same place on the stamp/cover, even though the stamp/cover was scanned at a different position? If it is a true moire pattern issue, I would think the pattern would show up in the same place on the stamp/cover, no matter where it is placed on the scanner.

Yes, the pattern is the same size and in the same place when it appears. I have scanned several items yesterday and today and the pattern has not reappeared so far. I place each cover in nearly the same place on the scanner bed to utilize a horizontal guide to keep the cover straight when scanned.

I have re-scanned the cover used as an example using the same settings and the rectangle did not appear. Strange!

HP just updated the software last week. Maybe there was a bug in it, but I have not been aware of any additional modifications to that update. Maybe the scanner is just getting old and there was a malfunction.

DonSellos

Wait until it happens again and when it does immediately scan again (don't touch the cover/stamp) but just change the DPI scan resolution (i.e from 300 dpi to 150 dpi). If you can repeat this, and the pattern comes and goes based upon the dpi resolution you are scanning in, then it is highly likely a software issue.
If it continues to show up on different items (stamps/covers) and changing the dpi setting does not seem to impact the pattern from appearing, then you have a CCD (hardware) issue and start shopping for a new scanner.
Don

Edit: I am leaning towards a software issue.

Thanks, Don, for your added advice. I'll follow it if the image reappears and post my experience here.

DonSellos

A FYI reply.

I scanned this cover today at 300 DPI and the small rectangle appeared in the usual place.

Following Don's instructions, I re-scanned the item at 150 DPI without moving it on the scanner bed and it turned out fine. This cover has a photographic image of the city screened onto it. This image apparently triggered the small moire.

If the moire appears, the fix seems to be re-scan at lower DPI. Thanks, Don, for the good advice.

DonSellos

Don,
for covers, I have my scanner set to scan the entire platen at 200dpi
I can scan numerous items of varying sizes, on the go.

I then deskew, and crop, the finished scans are very clear and no pixelling under zoom.

DonSellos,

Do you have descreening turned on in your scanner software?

Since DonS only noticed this right after a software update chances are good that his software has an issue. Keep in mind that a scanner software update often includes the scanner Twain driver AND the scanner application. DonS could further troubleshoot if he had a dedicated scanner drive/app like Vue Scan (which would not use the manufacturer software).

His other option is to scan at a resolution that avoids the pattern until they have another software update or revert back to his older version.
Don

PostmasterGS: I don't know. I don't see a descreening feature on my scanner and I'm not tech savvy enough to get in the software.

The work-around that Don suggested takes a little extra time, but is easy to do. I'll continue with it for the interim. If there is a glitch in the HP software update, maybe HP will get it fixed in the near future.

Again, thanks to all for the suggestions.

DonSellos

Don, I use HP and they have a fantastic customer support system.

Peter

Thanks, Peter, for the suggestion. I need to open an account with HP to get to their customer support. So far, I haven't had the motivation to to that. Tried the virtual chat with no success.

Don