digital editions scanners buying guide
Post on 11-Mar-2016
Embed Size (px)
DESCRIPTIONDigital Editions Scanners Buying Guide
1Scanner Guide www.photoreview.com.au Media Publishing 2010
Most people have a collection of old photographs they would like to digitise. Although the majority of them will probably be prints, theres a good chance at least some of them will be 35mm slides or negatives. Some may even be in other formats.
There are some compelling reasons for digitising old photographs:t *UQSFTFSWFTUIFJNBHFTGPSGVUVSF
generations to enjoy.t *UNBLFTUIFQJDUVSFTFBTJFSUPPSHBOJTF
catalogue and archive.
CHOOSING AND USING IMAGE SCANNERS.
t:PVDBOSFTUPSFGBEFEDPMPVSTBOESFNPWFblemishes that have affected the photos over time.
t%JHJUJTJOHNBLFTUIFJNBHFTFBTJFSUPSFQSJOUboth immediately and in the future.Most photo-capable scanners can be used
for digitising documents although dedicated document scanners seldom provide adequate image-scanning capabilities. However, you can buy multi-function devices that combine photo-capable printers and scanners and also provide copying and faxing capabilities.
*OUIJTHVJEFXFMMFYQMBJOXIJDIGFBUVSFTUPlook for when buying a scanner, how to obtain the best results from different types of images and how to set up a scanner for print and lm scanning. Well also provide some tips for scanning old black-and-white photos and advice on ways to improve the results of your scans.
Finally, well discuss different ways of outputting your images and strategies for storing the digitised image les. Well also look at how much storage you require for your image archive.
Scanner Guide www.photoreview.com.au Media Publishing 20102
What type of scanner do you need? This guide will concentrate on scanners for digitising photographs and look at two types: atbed and lm. Flatbed scanners are the most popular because they are cheaper to manufacture, easier to use and much more versatile. For business use, they are the only option available for document scanning and many businesses acquire a scanner as part of a multi-function device.
Photographers with a mixture of prints, negatives and slides to digitise will nd a dedicated atbed scanner is the best choice because it covers all types of original images.
Low-cost lm scanners are available but their capabilities are usually very limited. Many will only scan negatives, most are restricted to 35mm format and the DIFBQFTUNPEFMTTDBOBUSFMBUJWFMZMPXSFTPMVUJPOT*UTusually worthwhile paying a little more for a atbed scanner that can scan lmstrips and mounted slides.
Features to Look For1. SIZE How large are your originals? The most popular size for documents is A4, while 35mm lms outsold other sizes many times over. So its easy to understand why these sizes dominate their respective markets. Most A4 photo scanners can accommodate 120 and 220
Many people acquire a scanner as part of a multi-function printer.
Photo enthusiasts and people with lots of old photographs on lm should seek out a high-resolution scanner with lm-scanning capabilities.
Many A4 photo scanners provide lm holders that can accommodate both mounted slides and lm strips. Enthusiasts models often include holders for medium format (120/220) lms.
One touch buttons make it easy to scan for copying, printing and faxing or you can send the digitised image directly to image editing software.
lm strips and the high-end models are often able to scan 4x5-inch and even 8x10 inch negatives and transparencies.
*GZPVCVZBnBUCFETDBOOFSXJUIBO"TDBOCFEJUDBOBMTPTDBOTNBMMFSEPDVNFOUTBOEQSJOUT:PVDBOscan larger originals but only segment by segment. And the segments must be joined afterwards in suitable software.
2. ERGONOMICS8JMMUIFTDBOOFSmUPOZPVSEFTLUPQ %PFTUIFMJEPQFOwidely enough to allow you to scan pages of a book (if required)? How well does the scanner interface with your computer and does it offer stand-alone TDBOOJOH *OFYQFSJFODFEVTFSTBOEUIPTFXJUICBTJDcomputer skills, may nd scanners with one touch buttons for copying, printing and faxing easier to operate. More experienced photographers will want greater control and efcient integration with their computers.
Most document scanning involves a simple copying process that converts the text and graphics into pixels. However, many scanners have built-in GBDJMJUJFTGPSDPOWFSUJOHUIPTFQJYFMTJOUP1%'GPSNBUfor easy and secure sharing. Some also come with Optical Character Recognition (OCR) software that converts them into editable text. A few also include *OUFMMJHFOU$IBSBDUFS3FDPHOJUJPO*$3GPSIBOEXSJUJOHrecognition and Optical Mark Recognition (OMR) that
EJTUJOHVJTIFTBOESFQSPEVDFTDIFDLCPYFT%PDVNFOUTmay also be able to be converted into HTML pages for use on websites.
Automatic document feeders are also available for business scanners, either as a built-in facility PSPQUJPOBMBDDFTTPSZ*GBOZPGUIFTFGFBUVSFTBSFimportant (or even useful), make sure you check the scanners specications and features list before purchasing.
3. RESOLUTION Resolution should be dictated by the size of the
original images and required output dimensions. When evaluating a scanner make sure you know the difference between optical resolution and interpolated resolution. The former denes the limits of the resolution the scanner supports.
*OUFSQPMBUFESFTPMVUJPOJTVTVBMMZBMBSHFSOVNCFSbecause it refers to the maximum number of additional pixels the scanner adds in to end up with a specic output size. Since interpolation is better left to post-capture software, this gure should be ignored.
Two numbers represent optical resolution in scanner specications: the number of sensors in the sensor array and how nely the stepper motor can move the sensor across the scanbed. The second gure is usually higher - and largely irrelevant. (Well cover resolution in detail on Page 3.)
Although some manufacturers claim interpolated resolutions as high as 19,200 ppi, such numbers carry little real value, because interpolation doesnt increase the amount of detail captured and theres no limit to the number of interpolated pixels that can be added.
4. PRICEGenerally speaking, the more money you invest in a scanner, the better its performance and the more enjoyable it is to use. Cheap scanners are slow; their software is usually clunky and purchasers soon become frustrated and discouraged. Top-of-the-range scanners make scanning easy with batch scanning DBQBCJMJUJFT:PVDBODPWFSUIFTDBOCFEXJUIQSJOUTslides or lmstrips and the scanner will separate them into individual digitised les. Scanning resolution is usually higher and hues and tones are accurately reproduced.
3Scanner Guide www.photoreview.com.au Media Publishing 2010
Scanners operate a lot like digital cameras in that they create a copy of an object constructed from millions PGUJOZAQJDUVSFFMFNFOUToPSAQJYFMT*OCPUIDBTFTan image sensor is used to make this conversion via a digitising processor chip.
The difference between a scanner and a digital camera is straightforward. The camera uses an array of light-sensitive photosites in a rectangular grid and the image is captured with a single exposure. A scanner has a single-row array of similar photosites and this is moved (scanned) across the original by a stepping NPUPS*GBTDBOOFSDMBJNTBOPQUJDBMSFTPMVUJPOPG4800 x 9600, the 4800 refers to the number of photosites in the scanning head, while the 9600 gure represents the number of steps by which the head is moved to cover the scanbed.
The end result of a scan is virtually indistinguishable GSPNBOJNBHFmMFDBQUVSFECZBEJHJUBMDBNFSB*Ofact, the same le formats are used to output the digitised images.
This similarity enables scanners to be used to photograph small, three-dimensional objects, such BTKFXFMMFSZBOEFMFDUSPOJDDPNQPOFOUT$*4TDBOOFSTIBWFBNVDITNBMMFSEFQUIPGmFMEUIBO$$%TDBOOFSTmaking them unsuitable for this application.
When choosing a scanner, pay attention to the following features:
1. RESOLUTIONResolution is usually quoted in either pixels per inch (ppi) or dots per inch (dpi), depending on the context. *NBHFSFTPMVUJPOJTFYQSFTTFEJOQQJXIJMFUIFPVUQVUresolution for inkjet printers and screen resolution are usually specied in dpi.
Scanner resolution may be expressed in either form because digitised images usually end up being printed PSEJTQMBZFEPOTDSFFO*OUIJTDPOUFYUQSJOUFSTXJUIa resolution of 1440 dpi can lay down 1440 ink dots per inch while simulating the colours in a digitised image.
*ODPOUSBTUWJEFPNPOJUPSTTVDIBTDPNQVUFSBOE57TDSFFOTBSFSFMBUJWFMZMPXSFTPMVUJPOEFWJDFT*Omost cases, screen resolution is normally between 70 and 100 ppi.
The resolution of your scans should be dictated by the ways you plan to use the digitised images.
For most people it will be one of these alternatives:A. The image will be used at the same size as the
original. B. The image will be enlarged as it is scanned.C. The image will be enlarged and edited after
2. DENSITY RANGELike a digital camera, a scanner must be able to capture the full tonal gamut of the original without blowing out the brightest highlights and turning the shadows to black. This isnt as simple as it seems.
A pixel is dened as the smallest part of a digital image. Each pixel is a sample of part of that image and each has its own address that denes its position with respect to the image as a whole. Pixels in black and white images and documents are
dened by different values of grey, while those in colour images and documents have specic values of red, green and blue (or yellow, magenta, cyan and black when digital images are printed).
The density of the pixels per scanned unit area represents the resolution of the image, which is normally expressed as a pixels/inch ratio. More pixels per square inch equates to higher resolution