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Searching for a Decent Scanner?
Stumped about Scanners asks: "My little sister's scanner is acting up, so she's in the market for a new one. However, the software she wishes to use it with (some funkadelic 'music OCR' thing that lets you scan sheet music and transforms it automagically into MIDI files) claims that it doesn't work too well with HP scanners. And, truth be told, I've never known much about which scanners are good and which are crap. So, which scanners lately are decent? Which are crap? I know that DPI matters very little (just like it does in printers)-- it's quality that matters. Could the SlashDot community provide some info on which scanners (some from HP and some not from HP) are decent? Are there any quasi-reputable sites (a la Tom's Hardware?) that have reviews on such things?"
AFAIK the quality is top, the price correct, and it plays very nice with any OS (espacially p'n'p under linux with xsane).
aurelien
Although DPI matters it isn't an over riding factor in quality. This is true for scanners, printers and digital cameras. Your assertion fails because you assume that all scanned/printed/imaged pixels are equal. They are not.
A very good illustration of this is with color scanning. If you buy an expensive scanner its color accuracy should be quite good. If you buy a cheap scanner, not so much. Something that is common is getting dark blue for black.
Ah! You say, if you *really* care about the color accuracy (and who does?) then you just "apply a filter" in Photoshop. Not so fast -- if black comes in as dark blue, the question is what does dark blue come in as? if it also comes in as dark blue you just lost information and it can't be recovered.
Even if there is little information loss, "just" compressing of color space then it is something a bit beyond a simple filter. Color matching software is about the only way to deal with this problem, something Apple provides out of the box and is little used elsewhere.
My first scanner was a UMAX 1200 and with a scan target and some software I was able to create a color match profile for that scanner. The improvement in scan quality was very significant.
The short of it? It doesn't really matter if you scanner can go to 48000000 dpi if all of those "dots" are garbage. That's why getting a quality scanner is important. Scanning in a resolution higher than you will use is also a waste of time and storage, but that is another matter.
For digital cameras you get the same issues as with scanners. Ooo! Its 500 Mega Pixels! Means absolutely nothing if the reds are washed out, the blacks are blue, etc.
And printers are even more fun because people use different inks on different papers so color matching is even more hit and miss. But the original weakening of DPI as being useful to gauge printer output was when inkjet printer resolution started getting ramped up.
The problem is that the printer could place, say, 720 dots in an inch, but each dot was maybe 1/72 inch across (from memory -- at this point I don't remember the actual size of a dot on the inkjets as I don't use them). So all you got out of the 720 DPI was overly wet paper. (Well, it also allowed some smoothing of diagonals, but considering the bleeding problem with inkjets that point is of questionable value.)
Thoromyr