On 7/20/05, Jon Noring <jon@noring.name> wrote:
Certainly, it takes a scanner longer to scan at 600 dpi than 300 dpi, so for major book scanning projects, scanning speed is a factor to consider.
However, I would think that many projects submitted to DP are done by individuals who are only doing one to a few books in a year, not hundreds of them a week. So for them, choosing the slower approach may be acceptable to them, especially if they cherish the book and wish to assure the scans they make are of the highest reasonable quality for archival/preservation purposes.
(To the DP folk: what is the breakdown of book scans submitted to DP by users -- do just a few supply most of the scans, or are most of the scans submitted by a lot of people?)
http://www.pgdp.net/c/stats/pm_stats.php is the closest available. Note that meta-PM accounts (or whatever they're called) like BEGIN will throw the numbers off, as will items scanned by providers-only (proofraided pages or non-PM CPs). In any case, the majority of the texts available are scanned by the high-volume PMs. Note that I am #39 on the list, despite only having created 67 projects. Very few image repositories supply page images in color.. archive.org being the notable exception. (And how many people will download 2 gigs of TIFFs for a single work?) Also, I believe you are over-estimating the quality of the high speed scanners.. Juliet is constantly cleaning it to get decent B/W images. It has a tendency to gather book dust on mirrors and calibration areas, and get lines through the output.
Speed also depends upon the speed and quality of the scanner one uses. My scanner is a Microtek Scanmaker X6EL. A pretty inexpensive but reasonable quality flat bed scanner with 600 dpi optical resolution. Not exactly a speed demon. (Most flatbeds today are 1200 dpi optical, which is pretty much the practical limit for such scanners due to mechanism vibration and other factors, so the experts have told me.)
Err.. not sure about that. I just purchased a 4800 DPI optical scanner for scanning microform works, for a fairly reasonable price. The standard resolutions now seem to 2400 and 3600 DPI optical. (4800x9600, 3600x7200, and 2400x4800 in marketing speak.) As for scanning in full color 600 DPI.. I tried that on a few of the Beatrix Potter books, which are very dense with illustrations. It took significantly longer to scan them and process them in that fashion than my standard technique. (My standard technique for the Potters: 1st pass scan in 300 DPI greyscale, let Finereader threshold to 1-bit. Second pass for images, 600 DPI full-color. Then I descreen, adjust the levels and color balance, downsample to 300 DPI and save as PNGs.) Uploading the unprocessed 600 DPI plates is impractical, even for works as small as the Potter books. Ordinary books I leave the image processing for the PPs, except perhaps descreening. R C