I am not quite sure about what is being proposed in this thread.
daniel_reetz wrote:The idea is to give everyone a common standard with which to test their scanners.
I thought the idea, as proposed by bnz on the "DSLR like cameras" thread, was to determine the camera quality / price / resulting image sweet spot.
bnz wrote:what I'd really like to see are comparison shots in full resolution of the same single page with the low-budget canons pocket cameras done with sdm/chkd, such midrange non-dslr cameras with dslr-features, and "normal" dslr cameras like the canon t2i/550d and in the same conditions. It's kind of better to judge for yourself
And Daniel replied:
daniel_reetz wrote:What we really need is a standardized test page so we can all compare. Does anyone have any suggestions on how to make such a thing? I'm considering making a Print On Demand book, but I could just as well print a huge number of test pages and ship them worldwide. That way we could standardize on camera performance for book scanning purposes.
This forum has been working on scanner designs for a year and a half and as a prospective scanner builder or owner I am confident that any cradle / platen combination I choose will serve. What I am less clear on is the ideal camera that has enough but not too much resolution for the least cost. So I am very interested in isolating performance of DIY scanner cameras in some testing regime.
Comment #1: For the testing regime to work (for the resulting images to be comparable) input has to be controlled. If end testers print out their test pages, the input would not be controlled, because of both the different types of printers and their current state of repair / effectiveness. The test pages have to either come from a central source, or, less ideally but perhaps acceptably, be produced on machines at least likely to be roughly comparable, say, the output devices at Kinkos. Going to somewhere to print a file seems like a lot more trouble than clicking on a link to have someone send a standard test page within a couple days. If necessary, I am willing to be that central sender and am willing to kick in $20 to a collective printing cost (none, if black and white) / envelope / postage kitty.
Comment #2: Assuming input is comparable, presumably output can be comparable in being specified as one or a couple standard camera outputs, say the cameras' maximum-resolution JPEG and its RAW format, perhaps post processed in some standard way (if necessary - I don't know much about camera output). If the point is to allow people to decide for themselves, per bnz, then the ultimate output is not the image but forum members' computer monitors, none of which will likely render the images accurately, but, for any single monitor, will render all the images comparably to each other and allow bnz's general user to decide for themselves what camera to buy for his or her scanner.
Comment #3: Per Daniel's questions:
a) the best test-page size might that of a standard not-too-big book page, for the reason that effective resolution has to include cropping out all the excess generated by the mismatch of camera image shape and book page shape. So the test image should be the size of the most commonly scanned image of regular use
b) this is not pertinent if comment #1 is on the mark, but since Daniel asked, I have access to an allegedly 1200dpi monochrome laser, the Samsung ML-2851ND, and an allegedly 6000x2400, 4-ink, color inkjet, the Brother MFC-6490CW (btw, a cool device for having 11x17 scanning capability, and available for only $200 with free shipping and 2-year warranty)
c) the test pages should be black and white -- color test pages will be expensive to print centrally and so wildly diverse if printed locally as to not be usable for comparison purposes
d) other ideas:
--if the plan is to figure out a camera price / performance sweet spot, and that requires comparable images, wouldn't it be necessary to go beyond a standard test page to request certain conditions for scanning the test page, for example (I don't know, just throwing these out) use of some relative aperture (such as the most open, or the next-to-most open) / shutter speed / lighting intensity. Given the variation in the distance that scanners put the cameras from the page, and the variation in types of bulbs that are part of the scanner and the additional background light that is present, I can see that specifying picture-taking conditions is a challange. Yet for comparisons to be useful, this seems very important to me -- the effectiveness of OCR depends on a clean image, which depends on a high-contrast image. A perfectly great camera (irrespective of price, high or low) is imperfect for text OCR if the base images produced are too low-contrast, and that may be determined entirely by conditions rather than camera.
--if the plan is to figure out a camera price / performance sweet spot, we would want to assure a diverse sampling of cameras people might want to buy. We would want to figure out representative camera types that encompass all the major combinations of features. I'm no camera expert, so the following is the product of my rudimentary knowledge: the key features could be sensor size, megapixels, and lens characteristics like highest speed and maximum zoom. So the representative camera types would be combinations of sensor size categories, say 1/2.3, 1/1.7, micro 4/3s, and APS-C; megapixel categories of, say, 8-10, 10-12, and over 12; lens speed categories of, say, 2.0 or under, 2.0-3.0, and over 3.0; and zooms of, say, up 4x and over 4x. Those categories would make for 72 theoretical combinations (though probably quite a few less since so few small-sensor cameras have lenses faster than 3.0 or megapixel counts over 12 million), which is perhaps on the outer edge of practical for this forum community. Collapsing the 1/2.3 and 1/1.7 sensor size categories would make substantially less than 54 theoretical combinations, etc.