That is right. In addition, for certain printing (gold seal), digital camera delivers better result than scanners.
-----Original Message----- From: Code for Libraries [mailto:code4...@listserv.nd.edu] On Behalf Of Jonathan Rochkind Sent: Friday, May 01, 2009 2:38 PM To: CODE4LIB@LISTSERV.ND.EDU Subject: Re: [CODE4LIB] Recommend book scanner? Yeah, I don't think people use cameras instead of flatbed scanners because they produce superior results, or are cheaper: They use them because they're _faster_ for large-scale digitization, and also make it possible to capture pages from rare/fragile materials with less damage to the materials. (Flatbeds are not good on bindings, if you want to get a good image). If these things don't apply, is there any reason not to use a flatbed scanner? Not that I know of? Jonathan Randy Stern wrote: > My understanding is that a flatbed or sheetfed document scanner that > produces 300 dpi will produce much better OCR results than a cheap digital > camera that produces 300 dpi. The reasons have to do with the resolution > and distortion of the resulting image, where resolution is defined as the > number of line pairs per mm can be resolved (for example when scanning a > test chart) - in other words the details that will show up for character > images, and distortion is image aberration that can appear at the edges of > the page image areas, particularly when illumination is not even. A scanner > has much more even illumination. > > At 11:21 AM 5/1/2009 -0700, Erik Hetzner wrote: > >> At Fri, 1 May 2009 09:51:19 -0500, >> Amanda P wrote: >> >>> "On the other hand, there are projects like bkrpr  and , >>> home-brew scanning stations build for marginally more than the cost of >>> a pair of $100 cameras." >>> >>> Cameras around $100 dollars are very low quality. You could get no where >>> near the dpi recommended for materials that need to be OCRed. The >>> >> quality of >> >>> images from cameras would be not only low, but the OCR (even with the best >>> software) would probably have many errors. For someone scanning items at >>> home this might be ok, but for archival quality, I would not recommend >>> cameras. If you are grant funded and the grant provider requires a certain >>> level of quality, you need to make sure the scanning mechanism you use can >>> scan at that quality. >>> >> I know very little about digital cameras, so I hope I get this right. >> >> According to Wikipedia, Google uses (or used) an 11MP camera (Elphel >> 323). You can get a 12MP camera for about $200. >> >> With a 12MP camera you should easily be able to get 300 DPI images of >> book pages and letter size archival documents. For a $100 camera you >> can get more or less 300 DPI images of book pages. * >> >> The problems I have always seen with OCR had much to do with alignment >> and artifacts than with DPI. 300 DPI is fine for OCR as far as my >> (limited) experience goes - as long as you have quality images. >> >> If your intention is to scan items for preservation, then, yes, you >> want higher quality - but I canâ€™t imagine any setup for archival >> quality costing anywhere near $1000. If you just want to make scans & >> full text OCR available, these setups seem worth looking at - >> especially if the software & workflow can be improved. >> >> best, >> Erik >> >> * 12 MP seems to equal 4256 x 2848 pixels. To take a â€˜scanâ€™ (photo) of >> a page at 300 DPI, that page would need to be 14.18" x 9.49" (dividing >> pixels / 300). As long as you can get the camera close enough to the >> image to not waste much space you will be getting in the close to 300 >> DPI range for images of size 8.5" x 11" or less. >> ;; Erik Hetzner, California Digital Library >> ;; gnupg key id: 1024D/01DB07E3 >> > >