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Readable barcodes from scanned documents - Printable Version

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Readable barcodes from scanned documents - Karl Schneider - 06-16-2006

HP-41 Wand owners --

I just received a Solar Engineering user solutions book today -- something that has been missing from the list of documents scanned in the MoHPC CD/DVD set, although a scan is available from the CD/DVD set from the "41 site".

I have had only limited success getting the Wand to successfully read the barcode printed on normal paper from pages that have been scanned -- even high-resolution scans. I'm not sure if the problem lies in the small irregularities in the bars, or in the printer paper.

I would like to scan the Solar Engineering book for the MoHPC, but do want to ensure that the barcode can be read. Does anyone have any helpful suggestions?


-- KS

Edited: 16 June 2006, 11:02 p.m. after one or more responses were posted

Re: Readable barcodes from scanned documents - Wayne Brown - 06-16-2006

What kind of printer are you using? I've had difficulty reading scanned barcodes printed on an inkjet printer, but they worked much better when the same scan was printed on a laser printer.

Re: Readable barcodes from scanned documents - Dave Shaffer (Arizona) - 06-16-2006

How "high" is your resolution?

And, are you scanning in black and white or gray scale? I have found, contrary to what you might expect, that gray scale (at, say, 600 or 1200 dpi) actually seems to give better effective resolution than B&W at the same dpi. This is for Canon and HP scanners.

Try scanning in gray scale, and then use contrast enhancement to make it look more like B&W.

Unfortunately, the file sizes are a lot bigger for gray scale!

Re: Readable barcodes from scanned documents - Karl Schneider - 06-16-2006

Dave and Wayne --

Thank you for your responses. I used an HP LaserJet 6P for printing the scanned barcodes (from documents purchased from MoHPC and "the other site"). I have yet to attempt any scanning, and do not own a scanner.

My main query was whether the failure of the Wand to reliably read the printed-scan barcodes was due to the minor imperfections and irregularities, or to the reflectivity of the printer paper I used.

I do have a complete set of manuals for the Wand, as well as a copy of the HP Journal article about it. There might be some clues in those sources.

When I scan the Solar Engineering users' solutions book, I'd like to obtain crisp rendering of the barcodes with a reasonable file size. I certainly won't scan in color (there isn't much of it in the book), but it would be nice to "make do" with B&W instead of grayshade.


-- KS

Re: Readable barcodes from scanned documents - Marcus von Cube, Germany - 06-22-2006


you can still scan the barcodes in a different resolution and color depth than the texts. If you combine everything in one PDF and the resolution is correctly marked in the scanned data, Acrobat Reader should take care of the differences and output the highest available resolution to the printer whithout disturbing the scale.