View Full Version : O.T. scanner tutorial

06-22-2011, 09:37 PM
Can anyone steer me to a website(s), that provide tutorials on understanding and selecting a scanner? I think that it's time for me to acquire one, and once again my ignorance exceeds all expectations!:D

06-22-2011, 09:45 PM
What kind of scanner? Police/Fire/Rescue radio scanner, or automotive OBD I or OBD II, or what?

06-22-2011, 10:05 PM
Oops:o ! Sorry! I've gotten so caught up in trying to research the things. Flatbed scanners for images.

06-22-2011, 10:10 PM
Can't help you with that, but somebody knowledgeable will be along any time now...;)

06-22-2011, 10:24 PM
There used to be a lot of options out there but with film going by the wayside there is not much of a need to scan photos.

If you have a bunch of documents to scan look for something with auto feed. Like the one on http://woot.com today.

06-22-2011, 10:30 PM
Are you interested in photo scanner from a photographers point of view?
I would go for a scanner that does negatives and slides. Only way to capture anything with great detail. Scanning a photo is like making a photo copy from a photo copy.
If you just want to scan documents like magazine articles, any of the all in one laser/fax/copier stations should work for you. They are all junk, you get what you pay for.
Professional equipment has professional prices.

06-22-2011, 11:22 PM
Scanners for 35mm film are almost gone from the marketplace, replaced by flatbed scanners which can also handle film strips (but not very well, in my experience). If it is film you want to scan, this was the best site for reviews: http://www.imaging-resource.com/SCAN1.HTM.

I used to have an HP Photosmart S20 film scanner, but sold it several years ago. It did a good job, but film scanning lots of negatives is impractical (you won't live long enough to complete the task). For digitizing the odd 35mm negative or slide I now resort to photographing the image, with a macro lens on my Micro Four Thirds camera. This requires post-processing in an editing program.

Lew Hartswick
06-22-2011, 11:58 PM
I have been using for about 2 years a HP G3010 with good results.

06-23-2011, 01:31 AM
Shopping for scanners can be frustrating. They have usually have serious limitations and abysmal documentation. After reading the data sheets for various scanners, you will be ready to line the marketing bozos up in front of a firing squad for gross incompetence, deception, and outright fraud. Unfortunately, there are laws against improving the gene pool in this manner.

Real resolution vs fake resolution: some scanners are marketed with fake "interpolated" resolutions which may or may not be identified as such. Make sure you are looking at the real hardware resolution which will be the number of sensor elements per color on one axis and the stepper resolution on the other. High resolutions have advantages for scanning film negatives and for using your scanner like an optical comparator or for other measurement applications. Resolution also affects scanning books, pictures, etc. 4800x9600 is nice if you are trying to measure objects by scanning them (resolution of about 2 "tenths"). If you are trying to scan 35mm film/slides you need lots of resolution since the film is only about an inch wide.

Scan Area. How large can it scan? 8.5x11", 8.5x14" (legal), 11x17 (good for B-size drawings and books two pages at a time), large format (C, D, E).

Speed. How many pages per minute can it scan, at what resolution and color depth? The speed of the USB interface may limit the speed or the speed of the physical hardware, the image sensor, or the readout electronics. A 1200x1200 scan at 24 bits per pixel and 8.5x11" is 403 megabytes which will take 269 seconds or more to transmit over USB full speed, 6.7 seconds or more over USB high speed, and 0.646 seconds or more over superspeed USB. A 4800x9600dpi image will take 32 times longer. These numbers are based on 100% bus utilization and no overhead , which is better than you will get in practice. Many scanners are significantly slower than the bus speed would imply. If the scanner supports JPEG compression in hardware, that can speed up bus transfers (assuming it can acquire and compress the image fast enough); sometimes, you want raw pixels, though. You will notice that speed specifications are often conspicuously absent from data sheets. Waiting a minute per page to scan a large book or document (or bunch of documents) gets old fast. When scanning less than the full glass area, pre-cropping to a smaller window may improve speed. Also note that the the time it takes the scanner head to retract to the home position affects scanning speed. There are two numbers: how long does it take to scan a page and cycle time (how long from the start of one scan until you can start the next scan).

Depth of field: How far above the glass can the scanner focus. This is very important for 3D objects like a circuit board, or a mechanical part. Depth of field is usually terrible in USB scanners. Old scanners had an large optical path and could focus on objects some distance from the glass (maybe 1/2") but newer smaller/cheaper/usb powered units tend to have trouble focusing if the object is not absolutely flush with the glass).

Depth of field affects the parts of book pages that don't lie flat.

Scan to binding. One particular vender offers scanners (and they have a nuisance patent on this) which are supposed to be a little better at scanning books in the curved part of the page near the bindings. They cut the scanner off a little on one side so the book can drape over. Of course, you can only scan books one page at a time, not two at a time with this system. None of the manufacturers are smart enough to offer a scanner with glass and scanning optics at right angles so you can scan both pages of a book simultaneously with minimal spine effects.

Flush glass. Is the scanner glass flush with the top surface of the scanner? This is rare. Suppose you are trying to scan a C size drawing in 4 parts or, worse, a metal part which is larger than your scanner bed.

Is the cover removable? The cover or hinge can get in the way when you are scanning large objects.

Will it work upside down? Sometimes it makes more sense to place the scanner on the object instead of vice versa. I.E. heavy object or delicate book. Most will probably work upside down.

Duplex? Can it scan both sides on ADF fed pages? Usually not. If so, does it feed the paper twice (slower and more handling of your documents).

Dimensional accuracy. How accurate is the scan dimensionally? Is it repeatable? Is it linear or is there distortion? An issue if you are trying to do measurements. Does it suffer from stiction (stick slip?) as the sensor slides along the glass? This would not only affect measurements but also high resolution scans of slides, etc. You will probably have to calibrate with gage blocks, etc. if you are making measurements.

Operating system compatibility. Some scanners will only work with Windoze and maybe Mac OS X. They won't work with linux (including EMC), freebsd, android, iPhone OS, etc. What operating system does the manufacturer provide drivers for and do they provide adequate documentation to allow developing open source drivers or your own custom software. Devices which have open source drivers can be found here:
Visioneer is particularly bad in this area; if one of their scanners happens to work it is because it uses the same chip as someone elses.

Attachments: Full size transparency lid, slide/film strip transparency adapter, automatic document feeder.

Dynamic Range/Bit Depth: How many bits per pixel? 24 (8 red, 8blue, 8 green), 36, 48, etc. If you need high dynamic range (light and dark areas), this can matter.

Color method: does it have 3 sensors per pixel (tristimulus, one for each color) or does it flash 3 different color LEDs onto a single sensor? If you are doing something exotic like using your scanner as a camera back or trying to use it to build an actual optical comparator, this matters. If it uses the three color flash method, then the transparency scanner attachment may need a motorized light source to follow the scanning head; if it uses the the 3 sensor method, then it can use either a motorized light source or full area illumination (which might require more power for lights, offset by motor power) and may require calibration for uneven field illumination).

Light source. Usually LED or Fluorescent. Fluorescent lamps (or their ballasts) wear out and need to be replaced and color needs to be calibrated. Fluorescent lamps have a warm up time. Some scanners kept fluorescent lights on all the time, which helped with warmup but wasted power and wore out the lamps faster.

How good is the color calibration? Does it include built in color targets?
Some color calibration targets which can be used with various pieces of color calibration can be found here:

All-in-ones: If the scanner is part of an all-in-on printer/scanner/copier/fax type unit, can you scan pages when your ink cartridges are empty? Yes this is really a problem on some units from HP, Epson, Cannon, brother, kodak, etc.

Angle of illumination. Usually 45 degrees is good for diffuse objects such as paper but not good for surfaces with specular reflection like aluminum or stainless steel. The light just bounces off 45 degrees the other way and misses the image sensor. I have yet to see one that lets you select between 45 degree and straight on illumination.

Accessory buttons. Some scanners have buttons that automatically launch appropriate software for various tasks or to start a scan without messing with the computer in an application which is already running. If space limitations mean the scanner will not be located in a position where you can conveniently use the keyboard/mouse, having a start button helps.

Interface: USB, ethernet. Some older scanners had SCSI or Parallel Printer Port interface.

ADF method. Some scanners feed the paper onto the flat bed for scanning, but many these days keep the scanning head stationary and just feed the paper past a separate window on the glass. This is mechanically simpler and faster. Feeding onto the bed tends to involve belts on the underside of the lid which show up as noise in the scan outside the borders of the paper and may leave streaks on the glass.

Background. What color is the background (backing) on the lid? Is it white/black/chroma key green/chroma key blue? White will waste less ink/toner when printing uncropped pages but can make it harder to auto crop. Cropped pages waste less ink than uncropped ones. Colors other than white may bleed through thin paper darkening or coloring the scan; however, a black background reduces the effect of print/images on the back side of the paper bleeding through. Does the scanner come with multiple interchangeable backgrounds? Is the background cleanable? Is there a background color on the ADF scanning area?

Hinge. Does it have a flexible hinge or one which can elevate? Otherwise, if you have a book, magazine, or other thick object, the lid will not close properly

USB Powered or do you need AC power? If AC, does it use a clunky wall wart, have the power supply built in, or have an external power adapter
with a cord on both ends? If a wall wart, is it power strip friendly. Is it USB powered, does it get power from the normal USB data cable or does it need a Y-cable or extra cable to plug into multiple USB ports to get more power? Implementing some features may require more power than is available via USB but a separate power connection is inconvenient.


06-23-2011, 01:31 AM
Service manual: Is a service manual with schematics, calibration, and repair info available for this product?

Bundled software. Does it include OCR software for your OS? This is the one that will cost you $$$ if it is not included. Most other uses, there is free software available.


Warranty period?

Sellers return policy?

Shipping cost to return if not local?

Some of the newer HP all-in-ones apparently have the ability to scan directly to a memory card (no computer needed); of course you will be limited to a low resolution LCD preview, if any, for spotting bad scans.

I forgot to mention that depth of field can cause pages that don't lay flat to be out of focus and not just in the spine area - distortion caused by the binding of a book (even a thin one) or magazine can cause significant portions of the page to not lay flat. Depth of field can also be an issue scanning slides, especially ones which curled up.

Multiple lighting angles can also be useful for some originals that might have glare problems or defects.

ADFs are generally not meant to be used with photos, though some have had some success.

Some scanners will let you fill the scanner with slides or film strips but many are limited to a smaller area and also may not scan full size transparencies.

When scanning metal, odd shapped, or greasy objects, you may want to protect the glass with a plastic overhead transparency sheet.

Wikipedia article on the dreaded Contact Image Sensor (CIS) that causes the depth of field problems:

Reviewers also often omit essential details, like scan speed.

You may find you need more than one scanner for different purposes due to a shortage of good general purpose scanners.

An old Mustek 1200UB (1200x600) scanner: 600dpi 8.5x11 24bit color (100MB) on USB full speed (USB 1.1): 130seconds to scan, 158 second cycle time. 46seconds scan/71seconds cycle at 300dpi. 1200dpi (actually 1200x600) 297second (5 minute) cycle time.
Lets see, the 1920 edition of american machinists' handbook is about 780 pages or 390 scans or over 17 hours scanning time (if you don't get distracted with hurry up and wait).

One scanner worth looking at specifically for scanning 3D objects is the Epson Perfection V30, which can be had for $60 on amazon. Just stumbled across that one. Claimed 4800x9600dpi optical/hardware resolution. 48bit/pixel. Manufacturer crows about a 180 degree flip open lid for scanning books and "3D objects". Depth of field not specified but one review reports up to 0.5". http://flatbed-scanner-review.toptenreviews.com/epson-perfection-v30-review.html No technical docs/open source drivers but the manufacturer does have a proprietary linux driver which apparently works with SANE. No transparencies or ADF so it isn't very good for archiving documents or 35mm film/slides. One FAQ answer suggested that it might have a small film scan area (lid seems too thin and marketing doesn't mention it - sometimes they link FAQ entries to inappropriate products). USB Hi-speed. Dip****s at epson don't give the scaning speed. One mac reviewer was impressed by the speed - she should not have been. http://www.maclife.com/article/reviews/epson_perfection_v30 47 seconds to 1 minute 33 seconds per page (depending on file format saving to). But maybe she had it plugged into a slow USB port. Given the scarcity of scanners with any depth of field, worth a look.

Now that their website has come up, I can see epson makes a few more models with depth-of-field. The V300, V600 are also touted as scanning 3D objects. V300 is about $20 more and does do transparancies (up to 4 slides or 6 frames 35mm) but no ADF. Lid hinge does telescope up to 1" for thick books and flips 180 but does not look removable (wire has no connector); would be awkward for upside down use. Lid hinges on right side rather than back which might be a problem if you keep your scanner on the left side of the desk (as I do), though you can rotate 90 degrees (rotate 180 buttons end up in back). V300 specs have notation" Efective pixels: 40,800x56160 pixels at 4800dpi. Scanning area may be restricted if resolution setting is large." The V30 also had a high rise lid; maybe you can even remove it since no transparency adapter cord. V330 also mentions 3D objects. Their UK site claims scanning speed 29 second A4 size 600dpi and 7 second preview. V500/V600/V700/V750 don't mention 3D objects. V330 looks about the same as V300 but costs $20 more and includes arcsoft scan-n-stitch software for joining multiple scans together (you could use hugin/panotools for free); glass is not flush with top surface. Likewise the V33 looks like a V30 with stitching software. V300 looks like the best of the bunch with depth-of-field capabilities (V330 if you want to pay for unnecessary software). None of those have ADF.

A few other manufacturers have models that hint that they might have some depth of field:
Xerox 7600 "Hinged Lid allows you scan thick items like books or 3D objects"
Epson GT-1500 "The 8.5" x 11.7" flatbed lets you scan bound documents, such as books and magazines, and even 3D objects. "
HP Scanjet 5590 "Scan 35 mm slides and negatives with the included transparent materials adapter, plus documents, pages of books, and 3-D objects"
HP Scanjet N6350 "Scan Media Types: Paper (plain, inkjet, photo); envelopes; cards (index, greeting); 3-D objects "
The 7600 is only 1200dpi resolution, no ADF, no transparancy and costs as much as the epsons. The other three have an ADF and cost over $250. The Scanjet 5590 offers duplex ADF scanning, 2400dpi, transparencies, "Scan up to 8 pages—or 4 images—per minute and preview scans in about 7 seconds", "Automatic document feeder speed: Up to 8 ppm/4 ipm (b&w)". GT-1500 claims up to 20 pages per minute, but takes 6 seconds for a preview scan.

HP Scanjet G3110 is mentioned as having depth of field. Likewise the scanjet 8300 and scanjet G4010 ($140). And the Scanjet G4050:

Evan has a flatbed with good depth of field but it is an obsolete parallel port model.

Here is a nice comparison of depth of field:
The canoscan 8400F is the one with depth of field. USB 2.0, 3200x6400dpi, discontinued, $170 refurbished.

Tutorial links:

06-23-2011, 06:43 AM
After a lot of looking I got a Epson Perfection 4490 Photo. Been using it to scan a lot of negatives from old large format B&W to color 35mm. I have been very happy with it. The thing that slows down scanning negatives is mounting them in the film holder so to speed thing up I purchased a second holder which cost less then $5.00.

06-23-2011, 08:26 AM
have a look at Wayne Fulton's site:

http://scanhelp.com/ some individual tips here

www.silverfast.com high-end scanning software

I am not associated in any way with sites offering commercial products