| Flatbed scanners generally deliver the best | | | | feature USB ports - either Hi-Speed USB (USB 2.0) on |
| combination of quality, flexibility, and usability in scanning. | | | | more recent models, or the earlier USB 1.1 standard. |
| They can be used to scan different kinds of media, | | | | Hi-Speed USB is backwards compatible with the USB |
| including photos and film (with the additional use of a | | | | 1.1 and has a data transfer rate of 480 megabits per |
| transparency adapter); they can be used to scan text | | | | second (Mbps). Higher-end scanner models are likely to |
| for OCR and document archiving; and they can be | | | | include the FireWire interface as well, allowing |
| used to scan material of varying sizes and thicknesses | | | | scanners to be used in advanced, professional such as |
| - from small postage stamps to large mechanical | | | | audio/video transfer and data storage. Scanners with |
| blueprints and 3D objects. To determine the flatbed | | | | either USB or FireWire interface are hot swappable - |
| scanner for your needs, this buying guide covers some | | | | which means the scanners can be plugged or |
| of the more important flatbed scanner specifications | | | | unplugged from other devices to which they are |
| that you will need to know.Bit depth and color | | | | connected without having to turn the scanners off and |
| passPractically all scanners today are single-pass | | | | on. Older scanners will include SCSI or parallel ports, |
| types with 48-bit color. Gone are the scanners of yore | | | | but you shouldn't have to consider these legacy-type |
| that required three passes to capture the full RGB | | | | models - unless you are using the scanner to connect |
| (red, green, blue) color information from an image in | | | | to older computers. When shopping for a flatbed, any |
| individual, painstakingly slow takes. Gone too are 24-bit | | | | scanner with a Hi-Speed USB port should be |
| and 36-bit scanners that proved sufficient in the past | | | | purchase-worthy, but consider getting a model with |
| for delivering up to 68.7 billions of color.Today's | | | | dual Hi-Speed USB and FireWire interfaces to expand |
| single-pass, 48-bit scanners are fast and can | | | | your range of possible connections to many other |
| theoretically capture up to 250 trillion colors - clearly | | | | devices and peripherals.Scan SpeedSpeed |
| more color than the human eye can distinguish or what | | | | specifications in flatbeds are hard to determine - unless |
| monitors and printers can reproduce - but impressive | | | | the scanner manufacturer provides the specs or the |
| nonetheless for the promise of yielding hues as close | | | | exact conditions in which material is scanned. Scan |
| to life as possible and delivering smoother color | | | | speeds can run from seconds to several minutes, |
| gradations. Ignore all but single-pass scanners when | | | | depending on a wide variety of factors. For instance, |
| shopping for a flatbed, and aim for 48-bit color as well. | | | | to compare scan speed between two comparable |
| Consider lower-bit models (such as 42-bits) only if your | | | | models, one will need to know the size of the material |
| scanner of choice has other specs that a higher-bit | | | | being scanned, the resolution setting, the interface |
| counterpart may not have - such as patented | | | | being used, and the processing speed and power of |
| technologies and special features - that more than | | | | the computer to which the scanner is connected. |
| compensate for the lower bit depth of your selected | | | | Check speed claims carefully if these are made at all; |
| model.ResolutionThe resolution of a scanner | | | | it may help to do an actual or sample scan with the |
| determines the level of detail that can be captured; the | | | | model of your choice, and see if you are satisfied with |
| higher the resolution, the sharper the scan will be. | | | | the speeds of the preview and actual scans. You |
| There are two types of resolution: optical and | | | | could also check to see if your flatbed model has |
| interpolated, with optical resolution being the more | | | | been reviewed in computer magazines or sites and |
| important spec, as it relates to the scanner's actual | | | | rated for speed, as benchmark tests may give a more |
| optics and amount of information that it can sample. | | | | comprehensive picture on how fast the scanner |
| The interpolated resolution of a scanner is helpful only | | | | runs.Size of Scan BedMost flatbeds today will start out |
| in specific applications - such as scanning line art, | | | | with a standard scan bed size of 8.5" x 11.7", |
| where higher resolutions can even out jaggedness and | | | | approximating the dimensions of a letter-size image or |
| produce smoother contours.Most flatbeds today | | | | document. From there, various bed-size configurations |
| feature respectable specs for optical resolution, ranging | | | | could come into play, including 8.5" x 14" to |
| from 2400 dpi to 4800 dpi. Any scanner with such | | | | accommodate legal-size material, and 12" x 17" for |
| resolution figures would prove a respectable choice, | | | | large, tabloid-size scanning. It's usually a good idea to |
| since these specs are more than capable of delivering | | | | consider a flatbed with a bed size that's beyond the |
| sharp detail or enlarging images for most print | | | | bare minimum - in this case, larger than the barebones |
| applications. Remember, too, that scanning your images | | | | 8.5" x 11.7". Not only can you fit larger-sized material |
| in the full resolution of the scanner is likely to yield file | | | | onto the scan bed, you can also group several smaller |
| sizes of unmanageable proportions - without delivery | | | | pieces on the scan bed and perform batch scans |
| any discernible benefit towards increasing image clarity | | | | (scanning in groups) to save time and effort. Dynamic |
| or quality. So forget the resolution wars of the past | | | | RangeThe dynamic range of a scanner measures |
| when manufacturers trotted out their resolution specs | | | | how well it can capture the tonal range of an image, |
| to trump their closest rival. Instead, look for other | | | | ranging from the brightest highlights to the darkest |
| features today in flatbeds that may be more important | | | | shadows. Dynamic range is measured on a scale from |
| for your needs, or consider the resolution spec | | | | 0.0 (perfect white) to 4.0 (perfect black), and the single |
| TOGETHER with these other features when choosing | | | | number associated with a scanner indicates how |
| your choice of flatbed.CCD vs. CIS Sensor | | | | much of that range it can tell apart. The minimum and |
| TechnologyImage sensors in flatbed scanners can be | | | | maximum density values that can be captured by a |
| of two types - CCD or CIS. Scanners with CCD | | | | scanner are called Dmin and Dmax, respectively. If a |
| (charge-coupled device) sensors use a system of | | | | scanner's Dmin was 0.2 and its Dmax was 3.0, then its |
| mirrors and lenses for redirecting light reflected from | | | | dynamic range would be 2.8.While dynamic range is a |
| the original document to the CCD array. Because of | | | | term often bandied about, in truth the spec is more |
| the required optics, CCD scanners are more | | | | important for film scanners used to scan slides, |
| expensive to produce and result in bulkier scanners, | | | | negatives, and transparencies - as these types of |
| compared to their CIS counterparts. The image quality | | | | media have a broader range of tones compared to |
| produced by CCD scanners, however, is far superior | | | | photos, and for which a scanner's higher dynamic |
| to that produced by CIS scanners.CIS, or Contact | | | | range can make a difference. Most flatbed scanners |
| Image Sensor technology, is a more recent | | | | will have a dynamic range of 2.8 to 3.0, but don't be |
| development in which the sensor array lies just under | | | | surprised if you can't find it in the specs, as this is not |
| the scanner bed, so that the sensors catch reflected | | | | critical information needed by the average user looking |
| light directly. Since CIS scanners do not need a | | | | to scan photos or prints.SoftwareIn selecting the |
| complex optical system, they are cheaper to produce | | | | scanner of your choice, consider the software that |
| and are smaller in size, resulting in portable, lightweight | | | | comes with it. Software will always include the |
| models that may be prove ideal for cramped | | | | scanner's own driver or scanning software, as well as |
| desktops. CIS sensors also contain on-board logic that | | | | a host of complementary programs such as |
| consumes less power than CCD. But because the | | | | image-editing software like Adobe Photoshop to which |
| on-board logic utilizes space that would normally be | | | | the scanned image is delivered; optical character |
| used for the mirrors and lenses in a CCD to sense | | | | recognition software like ABBYY FineReader Sprint |
| light, scans from a CIS scanner are lower in quality. As | | | | for text scanning and OCR; color calibration software |
| a result, most people tend to forego the slight savings | | | | for higher-end scanner models; and even photo-repair |
| that can be obtained from a CIS scanner in favor of | | | | software like DIGITAL ICE. Check for extras as well, |
| getting higher-quality CCD models instead.Connectivity | | | | such as proprietary or exclusive technologies. |
| & InterfaceMost consumer-level scanners today will | | | | |