Digital Photo of large documents versus Scanning to computer

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I want to import images of several 14" X 18" ledger books into my computer. It has been difficult to find a decent document scanner that can handle this large format. Would it be wise to try shooting the pages with a digital camera and going straight into the computer with a JPG or TIF image??

-- Dave James (jdjames@cyberport.com), September 20, 1999

Answers

Of course it will depend on lots of factors:

1. What you want to do with them
2. The resolution capabilities of the camera you will use
3. The detail on the page(s) that need to be preserved

The resolution of even the best cameras out there can not compare to even a cheap desktop scanner - so you will not get the fine detail a scanner can reproduce, but it may be good enough depending on the detail(s) on the page, and what you want to do with the images.
Generally - if there's a lot of fine detail on the page, and your camera isn't a high-resolution model then you may not get anything worthwhile.
If the numbers on the page are big and bold, the camera is decent, you may get the quality you need. My recommendation is that you try some sample shots to see if it will work - but I have my doubts. I would guess that you would get pretty poor results if you tried OCR software of ledger sheets captures with a digital camera - OCR software is resolution hungry - it works reasonably well when you use a good scanner - and a digital camera will probably challenge the modest capabilities of most OCR packages.
If you just want to see what was on the page, and you can make out the numbers just fine - go for it.

Des

-- Dan Desjardins (dan.desjardins@avstarnews.com), September 20, 1999.


The trick is to work out how many pixels you want (and how many bits per pixel). If the writing is fairly clear, then 5 pixels per mm will probably do. This is 127 pixels per inch, or 1778 across 14 inches. This is pushing it for digital cameras, fine for a scanner (if you can find one), OK for digitising from 35mm film, even better for larger format film cameras.

You could also consider scanning/photographing each page in two sections, and re-combining them digitally.

As Dan says, it depends on your purpose. I wouldn't count on OCR working, if I were you.

-- Alan Gibson (Alan.Gibson@technologist.com), September 21, 1999.


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