Scanner Guide CHOOSING AND USING IMAGE SCANNERS.
Most people have a collection of old photographs they would like to digitise. Although the majority of them will probably be prints, there’s 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 *U QSFTFSWFT UIF JNBHFT GPS GVUVSF generations to enjoy. t *U NBLFT UIF QJDUVSFT FBTJFS UP PSHBOJTF catalogue and archive.
t :PV DBO SFTUPSF GBEFE DPMPVST BOE SFNPWF blemishes that have affected the photos over time. t %JHJUJTJOH NBLFT UIF JNBHFT FBTJFS UP SFQSJOU both 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 photocapable printers and scanners and also provide copying and faxing capabilities.
Scanner Guide
*O UIJT HVJEF XF MM FYQMBJO XIJDI GFBUVSFT UP look 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 film scanning. We’ll also provide some tips for scanning old black-and-white photos and advice on ways to improve the results of your scans. Finally, we’ll discuss different ways of outputting your images and strategies for storing the digitised image files. We’ll also look at how much storage you require for your image archive.
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Buying Advice What type of scanner do you need? This guide will concentrate on scanners for digitising photographs and look at two types: atbed and ďŹ 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.
3. RESOLUTION
Many people acquire a scanner as part of a multi-function printer.
Photo enthusiasts and people with lots of old photographs on ďŹ lm should seek out a high-resolution scanner with ďŹ lm-scanning capabilities. Photographers with a mixture of prints, negatives and slides to digitise will ďŹ nd a dedicated atbed scanner is the best choice because it covers all types of original images. Low-cost ďŹ lm scanners are available but their capabilities are usually very limited. Many will only scan negatives, most are restricted to 35mm format and the DIFBQFTU NPEFMT TDBO BU SFMBUJWFMZ MPX SFTPMVUJPOT *U T usually worthwhile paying a little more for a atbed scanner that can scan ďŹ lmstrips and mounted slides.
ďŹ lm strips – and the high-end models are often able to scan 4x5-inch and even 8x10 inch negatives and transparencies. *G ZPV CVZ B nBUCFE TDBOOFS XJUI BO " TDBOCFE JU DBO BMTP TDBO TNBMMFS EPDVNFOUT BOE QSJOUT :PV DBO scan larger originals – but only segment by segment. And the segments must be joined afterwards in suitable software. 2. ERGONOMICS 8JMM UIF TDBOOFS mU PO ZPVS EFTLUPQ %PFT UIF MJE PQFO widely 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 *OFYQFSJFODFE VTFST BOE UIPTF XJUI CBTJD computer skills, may ďŹ nd scanners with ‘one touch’ buttons for copying, printing and faxing easier to operate. More experienced photographers will want greater control and efďŹ cient integration with their computers.
Features to Look For 1. SIZE How large are your originals? The most popular size for documents is A4, while 35mm ďŹ lms outsold other sizes many times over. So it’s easy to understand why these sizes dominate their respective markets. Most A4 photo scanners can accommodate 120 and 220
‘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.
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 deďŹ nes the limits of the resolution the scanner supports. *OUFSQPMBUFE SFTPMVUJPO JT VTVBMMZ B MBSHFS OVNCFS because it refers to the maximum number of additional pixels the scanner adds in to end up with a speciďŹ c output size. Since interpolation is better left to postcapture software, this ďŹ gure should be ignored. Two numbers represent optical resolution in scanner speciďŹ cations: the number of sensors in the sensor array and how ďŹ nely the stepper motor can move the sensor across the scanbed. The second ďŹ gure is usually higher - and largely irrelevant. (We’ll 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 doesn’t increase the amount of detail captured and there’s no limit to the number of interpolated pixels that can be added.
4. PRICE Generally 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 :PV DBO DPWFS UIF TDBOCFE XJUI QSJOUT slides or ďŹ lmstrips and the scanner will separate them into individual digitised ďŹ les. Scanning resolution is usually higher and hues and tones are accurately reproduced.
Document Scanning
Many A4 photo scanners provide ďŹ lm holders that can accommodate both mounted slides and ďŹ lm strips. Enthusiasts’ models often include holders for medium format (120/220) ďŹ lms.
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Most document scanning involves a simple copying process that converts the text and graphics into pixels. However, many scanners have built-in GBDJMJUJFT GPS DPOWFSUJOH UIPTF QJYFMT JOUP 1%' GPSNBU for easy and secure sharing. Some also come with Optical Character Recognition (OCR) software that converts them into editable text. A few also include *OUFMMJHFOU $IBSBDUFS 3FDPHOJUJPO *$3 GPS IBOEXSJUJOH recognition and Optical Mark Recognition (OMR) that
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EJTUJOHVJTIFT BOE SFQSPEVDFT DIFDLCPYFT %PDVNFOUT may 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 PS PQUJPOBM BDDFTTPSZ *G BOZ PG UIFTF GFBUVSFT BSF important (or even useful), make sure you check the scanner’s speciďŹ cations and features list before purchasing.
Scanner Features Scanners operate a lot like digital cameras in that they create a copy of an object constructed from millions PG UJOZ AQJDUVSF FMFNFOUT o PS AQJYFMT *O CPUI DBTFT an 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 *G B TDBOOFS DMBJNT BO PQUJDBM SFTPMVUJPO PG 4800 x 9600, the 4800 refers to the number of photosites in the scanning head, while the 9600 ďŹ 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 GSPN BO JNBHF mMF DBQUVSFE CZ B EJHJUBM DBNFSB *O fact, the same ďŹ le formats are used to output the digitised images. This similarity enables scanners to be used to ‘photograph’ small, three-dimensional objects, such BT KFXFMMFSZ BOE FMFDUSPOJD DPNQPOFOUT $*4 TDBOOFST IBWF B NVDI TNBMMFS EFQUI PG mFME UIBO $$% TDBOOFST making them unsuitable for this application. When choosing a scanner, pay attention to the following features: 1. RESOLUTION Resolution is usually quoted in either pixels per inch (ppi) or dots per inch (dpi), depending on the context. *NBHF SFTPMVUJPO JT FYQSFTTFE JO QQJ XIJMF UIF PVUQVU resolution for inkjet printers and screen resolution are usually speciďŹ ed in dpi. Scanner resolution may be expressed in either form because digitised images usually end up being printed PS EJTQMBZFE PO TDSFFO *O UIJT DPOUFYU QSJOUFST XJUI a resolution of 1440 dpi can lay down 1440 ink dots per inch while simulating the colours in a digitised image. *O DPOUSBTU WJEFP NPOJUPST TVDI BT DPNQVUFS BOE 57 TDSFFOT BSF SFMBUJWFMZ MPX SFTPMVUJPO EFWJDFT *O most 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 scanning. 2. DENSITY RANGE Like 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 isn’t as simple as it seems.
Two terms are used to deďŹ ne a scanner’s dynamic SBOHF % NBY NBYJNVN EFOTJUZ BOE % NJO (minimum density). 5IF IJHIFS UIF % NBY mHVSF UIF NPSF EFUBJM UIF TDBOOFS DBO SFTPMWF " TDBOOFS XJUI B MPX % NBY ďŹ gure will reduce shadows to deep black. Most atbed TDBOOFST DMBJN % NBY mHVSFT CFUXFFO BOE which is adequate for reective originals (i.e. prints). % NBY mHVSFT DBO CF CPPTUFE BSUJmDJBMMZ CZ JODSFBTJOH exposure. This may look good in speciďŹ cations but generally results in blown-out highlights. 'FX NBOVGBDUVSFST QVCMJTI % NJO mHVSFT GPS scanners. However, it is safe to assume a high-quality TDBOOFS XJMM IBWF B % NJO PG BQQSPYJNBUFMZ :PV OFFE B EZOBNJD SBOHF PG BCPVU GPS QSJOU scanning, 3.2 for ďŹ lm negatives and 4.0 to 4.2 for TMJEFT 5IJT NFBOT B % NBY PG GPS QSJOUT GPS negatives and at least 4.3 for scanning slides. 3. BIT DEPTH Bit depth deďŹ nes the number of hues and tones (colours) a device can reproduce. For scanners, higher is usually better. Scanner bit depth ďŹ gures combine the
CWT T]S aTbd[c ^U P bRP] Xb eXacdP[[h X]SXbcX]VdXbWPQ[T Ua^\ P] X\PVT Ă€[T RP_cdaTS Qh P SXVXcP[ RP\TaP bit depth of the three colour channels: red, green and blue. So, a 24-bit scanner can reproduce 8 bits (255 colours) for each of the three channels. Most photo scanners support 48-bit scanning, which combines the data from three 16-bit channels, each covering 65,535 colours. The higher the bit depth, the larger the image ďŹ les. Lower bit depths are best for images that will be emailed or viewed on-screen.
Pixels Explained A pixel is deďŹ ned 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 deďŹ nes its position with respect to the image as a whole. Pixels in black and white images and documents are
The Red, Green and Blue values for the pixel in the lower left corner of the crop below left.
A typical digitised image.
An enlarged section of a colour image showing the pixel structure
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deďŹ ned by different values of grey, while those in colour images and documents have speciďŹ c 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 – and, therefore, more detail in the image. Contrast this with digital cameras, where the size of the photosites dictates image quality and exposure time controls how much light is DBQUVSFE *O B TDBOOFS UIF TDBOOJOH BSSBZ JT moved slowly enough to ensure the original is covered, making the size of the photosites much less relevant. The brightness range of the originals is also much less than typical photographic subjects.
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Setting Up a Scanner Most scanners come with shipping tape that should be removed before you switch the scanner on. There may also be a sliding lock that protects the internal components when the scanner is being moved. Once these protections are removed, you can connect the scanner to mains power, load the software and link the scanner to your computer via the USB cable. Software installation should be straightforward and most scanners will come with a User’s Guide that FYQMBJOT BMM GBDFUT PG UIF TDBOOFS T PQFSBUJPO *U JT often in an electronic format that can only be read on-screen.) There may also be image editing, OCR, copying and ďŹ le management utilities. To scan reective originals (prints and documents), simply place them face down on the scanbed and press the relevant button. One-touch buttons on TDBOOFST UZQJDBMMZ DPWFS 4DBO 1SJOU &NBJM BOE 1%' output. They will automatically select the appropriate resolution for the end usage of the scan. The Scan button will scan to an image editor if you have an application like Photoshop or Photoshop Elements loaded in your computer. The Print button will send the image to the printer that is connected to your computer and it will be printed if the printer is switched on. The Email button usually scans the image and opens your email application, adding the scan as BO BUUBDINFOU 5IF 1%' CVUUPO DSFBUFT B EPDVNFOU JO 1PSUBCMF %PDVNFOU 'PSNBU *U T DPOWFOJFOU GPS scanning documents that are to be shared without allowing others to edit them.
Place prints or documents face down, making sure the upper left corner is against the corner of the scanbed. When positioning prints or documents on the scanbed, make sure the document mat is in place and slide one corner of the print or document up into the corner of the scanner. Always align your originals parallel with the edges of the scanbed as this makes it easier to separate the scanned image from the background. This is particularly important when batch scanning (see right). When scanning several prints at a time, make sure there is a gap of at least 20 mm between them on all adjacent sides. Take care when closing the scanner’s lid to make sure the originals remain in place.
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or several mounted slides. More sophisticated scanners provide holders for 35mm and 120 ďŹ lm; entry-level models only offer 35mm holders and may not be able to scan slides.
Focusing Few scanners require focusing – and most provide no focusing adjustments. When scanning reective originals, the weight of the lid should be enough to hold them at and in place. Removing the transparency unit cover to reveal the secondary light source The ďŹ lm holders have been in the transparency window. designed to hold the ďŹ lm at the correct distance from the scanner When scanning ďŹ lm images on a atbed scanner head to keep the scans sharp. They also hold the ďŹ lm a special ‘transparency unit’ is required. This is a at. Film curl can be a problem when scanning large second light source that’s usually built into the lid of ďŹ lm formats and some holders grip the edges of the the scanner and covered by a slide-out document mat ďŹ lm and apply tension to keep it at. when reective originals are scanned. *G ZPV mOE ZPVS mMN TDBOT BSF TMJHIUMZ VOTIBSQ Scanners that support ďŹ lm scanning come with try sliding slips of paper under the edges of the ďŹ lm special holders that can accommodate a strip of ďŹ lm holders to see whether it improves sharpness.
Scanning Modes Most scanners will provide a range of scanning modes; typically Full Auto Mode, Home Mode and Professional Mode. Full Auto Mode is designed for novice users and only provides correction like dust removal and colour Films strips should be inserted into the holder with the shiny base side restoration. The Home Mode lets facing down. The images should appear backwards when they are loaded. you adjust brightness and colour and optimise text or line art scanning. The Professional Mode provides a full range Slides should also of adjustments and allows you to scan to a speciďŹ c be placed in the output ‘target’ size, such as A4. holder with the General purpose scanners and scanners in shiny side down multi-function devices may add an OfďŹ ce Mode and the images for scanning multiple documents of the same size. back-to-front. This mode usually requires an automatic document Avoid inserting feeder to be ďŹ tted. the images upside down so you won’t have to re-orientate them after scanning.
Batch Scanning Batch scanning can be a real time-saver when you have lots of negatives or slides to scan. Once you’ve set everything up, you can leave the scanner to do the job and concentrate on something else. This is handy because film scanning takes a long time. Top-of-the-range flatbed scanners can scan
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a dozen or more 35mm slides or negatives at a time and save each image as a separate file. Less expensive models can scan either four slides or two strips of six-frame negatives. Low-end film scanners and high-end multifunction devices are usually limited to a single strip of four negatives and many can’t scan mounted slides.
Matching Scans to Output Modern scanners are very versatile and most can IBOEMF B XJEF SBOHF PG PSJHJOBM EPDVNFOU UZQFT *O UIF Full Auto and Home modes, most will automatically JEFOUJGZ UIF UZQF PG EPDVNFOU PO UIF TDBOCFE :PV can check the setting (and change it, if necessary) by DMJDLJOH PO UIF %PDVNFOU 5ZQF CPY Before embarking on a scan, set the resolution, based on how you plan to use the scanned image. As a general rule of thumb, the following resolutions provide optimum ďŹ le sizes and output quality: 1. Set the resolution between 72 dpi and 150 dpi for images that will be emailed, uploaded to the Web or only viewed on-screen. 2. Set the resolution to 300 dpi for images that will be printed up to A4 size. 3. Set the resolution to 400 dpi for documents that will be converted into editable text and between 200 dpi and 400 dpi for documents that will be converted JOUP TFBSDIBCMF 1%' GPSNBU 4. Set the resolution to 200 dpi for documents that will be faxed. 5. For images that will be enlarged and edited after scanning, increase the resolution by the amount the image will be enlarged.
Scanning for Print Output Because up to 10 ink dots can be required to represent the colour of each individual pixel, printers require high resolution to deliver prints with adequate detail – and the larger the image is printed, the higher the scanning resolution required. Most printers have been designed to work with image resolutions of between 180 ppi and 300 ppi. For images that will be printed at small sizes, the higher (300 ppi) resolution is recommended as these prints will be examined closely and you want to make sure all the image details can be seen.
Most printers deliver the highest quality output at a resolution of 300 pixels/inch. (The optimal output dimensions for this image file are shown in the circled area.) *NBHFT UIBU XJMM CF FOMBSHFE UP " TJ[F Y 420 mm) are viewed from a greater distance so their resolution can be reduced a little (200 ppi to 250 ppi). Photos that will be printed at A2 size (420 x 594 mm) can be scanned at 180 ppi. These ďŹ gures should be
seen as the lowest resolution required for acceptable print quality at the speciďŹ ed image size. *U T HFOFSBMMZ FBTJFTU UP DBMDVMBUF UIF SFRVJSFE resolution if you work with inches, rather than millimetres.
Scanning for Screen Viewing Monitors and video screens show pixels directly at a 1:1 reproduction ratio. This means the image size can be EJDUBUFE CZ UIF TDSFFO TJ[F o BOE TDSFFOT EJGGFS JO TJ[F *G you have a 22-inch widescreen monitor, its resolution is
An image scanned at 1920 x 1080 pixels will ďŹ ll the screen of a widescreen HDTV set, regardless of the screen’s dimensions.
If the image resolution is less than the screen’s resolution it will be displayed at the pixel array size and black borders will appear around the picture. likely to be no more than 1680 x 1050 pixels; a typical )% 57 TFU DBO EJTQMBZ VQ UP Y QJYFMT *NBHFT XJUI MBSHFS QJYFM EJNFOTJPOT UIBO UIF TDSFFO resolution will be ‘downsampled’ to allow them to ďŹ t on the screen. Pixels are ‘discarded’ in the process so there’s little point in scanning to higher resolutions. However, if the dimensions of the scanned images are smaller, the pictures will appear smaller on the screen – and probably be surrounded by a black border. *U JT DPNNPO QSBDUJDF UP TDBO BU B SFTPMVUJPO PG FJUIFS 72 ppi or 92 ppi for images that will be viewed on a monitor or screen. There’s no ‘magic’ in either of these ďŹ gures; they simply prevent you from struggling to display or upload huge image ďŹ les when most of the pixels will be discarded when the pictures are displayed.
Calculating Scanning Resolution *U T FBTZ UP DBMDVMBUF UIF TDBOOJOH SFTPMVUJPO ZPV SFRVJSF with respect to the size of the original picture. However, because resolution is normally expressed in inches, calculations are easiest when the dimensions of the original are in inches as well. A 35mm ďŹ lm frame measures 1.5 x 1.0 inches. *G ZPV XBOU UP QSJOU UIF TDBO BU TOBQTIPU TJ[F UIF scanning resolution should be 300 ppi x 1.5 x 6 inches, which is 2700 dpi. (Because pixels are square, it’s only necessary to make this calculation for one side of the image.) To print a scan from a 35mm frame at A4 size (11.7 x 8.3 inches), the calculation is 300 x 1.5 x 11.7 = 5265 dpi. For A3 size (16.5 x 11.7 inches), the scanning resolution must be 7425 dpi, while an A2 enlargement (23.4 x 16.5 inches) requires a scanning resolution of 10,530 dpi. *G ZPV TDBO B Y JODI TOBQTIPU QSJOU BU EQJ the result is an image with 8640 x 5760 pixels, which could be printed at A2 size – although it’s doubtful the result would bear close examination due to the degree PG FOMBSHFNFOU *U XPVME CF CFUUFS UP TDBO BU EQJ which produces a 3600 x 2400 pixel image, which effectively doubles its potential output size, enabling you to enlarge the image to around A4 size. *G ZPV WF TDBOOFE UIF PSJHJOBM JNBHF BU B IJHIFS UIBO necessary resolution, the digitised image can be printed at smaller output sizes without loss of quality, However, image quality is always sacriďŹ ced when you exceed the maximum output size (shown in the table below) for the
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Resolution settings provided in a mid-range photo scanner.
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Setting Scanning Parameters *O BEEJUJPO UP SFTPMVUJPO UIFSF BSF TFWFSBM LFZ parameters involved when scanning images and it’s important to understand what they mean – and how important they are to different types of scanning. The scanner driver interface can be divided into between one and three sections, depending on the scanning mode selected. The Full Auto mode provides few (if any) adjustments. Most scanners will automatically identify the document type and set appropriate scanning parameters. All the user needs to do is press the Scan (or Start) button. This is the quickest mode to use and works best with images that are scanned at a 1:1 reproduction ratio. Some scanners let you apply automatic dust removal and colour restoration. However, no adjustments are provided for either correction. *O UIF )PNF BOE 1SPGFTTJPOBM NPEFT JU T VTVBMMZ necessary to tell the scanner what type of original image it’s dealing with.
Image Type Setting
End use for scan
48-bit colour
For colour originals that will be edited in a sophisticated image editor
24-bit colour
For colour originals that won’t be edited and where smaller ďŹ le sizes are required
Colour smoothing
For colour graphics, such as charts, diagrams or graphs
16-bit greyscale
To obtain the maximum tonal range in scans of B&W originals
8-bit greyscale
For B&W photos with few shades of grey
Black and white
For documents and line art in black and white
The Professional modes in high-end scanners require you to select between reective and ďŹ lm TDBOOJOH BOE QSPWJEF TQFDJmD *NBHF 5ZQF TFUUJOHT GPS different end uses for scans, which are detailed in the table above. .PSF TPQIJTUJDBUFE TDBOOFST NBZ QSPWJEF *NBHF Option settings that work like colour ďŹ lters when you’re scanning colour originals in the greyscale and black and white modes. They work by selectively suppressing or boosting the signals from the red, green and blue colour channels. With these options you can ‘drop out’ a particular colour to make it lighter or ‘enhance’ it to make it darker. These settings can be handy when you wish to convert a colour original with similar tones in different hues into a B&W print because you can adjust the lightness/darkness of different hues so they don’t end up as the same shade of grey. The final section of the driver interface covers Adjustments that enable users to tweak various parameters in order to obtain more usable scans. %FQFOEJOH PO ZPVS TDBOOFS BOE UIF TDBOOJOH NPEF you have selected, you may find the following tools: t %VTU 3FNPWBM t $PMPVS 3FTUPSBUJPO t #BDLMJHIU $PSSFDUJPO t %FTDSFFOJOH t 6OTIBSQ .BTL t %*(*5"- *$& 5FDIOPMPHZ We’ll cover these in detail on page 6.
Colour depth settings and Adjustments in the Professional mode in a mid-range photo scanner.
Cropping as you Scan Most photo scanners can scan a wide range of document types. There may also be a ‘greyscale’ setting, which is the best option for scanning black-and-white prints and negatives. The B&W setting in these scanners is better for scanning documents and line art – or photographs that have been printed in newspapers, magazines and books. 5IF %FTUJOBUJPO TFDUJPO PG UIF ESJWFS JOUFSGBDF NBLFT it easy to set the correct resolution for scans. There are usually three settings: Screen/Web, which sets the resolution to 72 dpi Printer, which sets the resolution to 300 dpi, and Other, which lets you set a different resolution. This section may include a Target Size dialog box where you can select the degree to which the original image will be enlarged with the scan. The ‘Original’ setting scans at a 1:1 reproduction ratio.
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Most scanners allow you to specify the area for scans, which means you can crop out unwanted sections of images as part of the scanning process. Some also provide a speciďŹ c Trimming function and you may also be able to lock the aspect ratio to keep the image correctly proportioned. Many scanners provide a Scale box to help you upscale or downscale the output size by an exact percentage. When you select a different Target Size from the original image, a marquee (dotted line) is TVQFSJNQPTFE PO UIF JNBHF :PV DBO ESBH UIF corners of the marquee in and out and the resolution will change automatically to maintain the pre-set output resolution. *G ZPV OFFE UP SPUBUF UIF NBSRVFF GPS B MBOETDBQF or portrait image without changing its aspect ratio,
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Images can be cropped for scanning by dragging the edges of the marquee in to frame a smaller area. click the orientation icon beside the Target Size dialog box. Cropping marquees can be copied and applied to a set of similar images. They can also be saved for future applications.
Image Correction Tools Most photo scanners come with facilities for removing dust and minor blemishes, restoring faded colours and CPPTUJOH TIBEPX EFUBJMT JO TDBOT PG CBDLMJU TVCKFDUT *O general, these adjustments can improve the appearance of your scans. However, they can’t work miracles so don’t expect all the blemishes to be removed from badly damaged originals – or full, lifelike colours to be restored when the originals have faded almost to vanishing. Dust Removal is mainly used when scanning images PO mMN *U TIPVME POMZ CF BQQMJFE XIFO ZPV DBO TFF dust or scratches on the surface of ďŹ lms or prints. %JTUPSUJPO BOE CMVSSJOH DBO SFTVMU XIFO JU T BQQMJFE UP images with no dust.)
Colour Restoration can be applied to prints and ďŹ lm scans and works mainly by boosting saturation (which is reduced in faded images). Most scanners apply the adjustment globally to the entire image. More sophisticated scanners allow users to select particular colours and boost their saturation by degrees, giving much more control over the end result. Backlight Correction can also be used with prints BOE TMJEFT *U CPPTUT TIBEPXT XJUIPVU BGGFDUJOH highlights and midtones. Many scanners allow you to adjust the level of correction to obtain natural-looking results.
The Unsharp Mask setting is used to emphasise the edges of different areas in the picture in order to make the entire image look sharper. Because of the way scanners sample images and documents and average the scanned values, scans are seldom quite as sharplooking as the original image. *G ZPVS TDBOT MPPL EJTBQQPJOUJOHMZ TPGU JU DBO CF worthwhile experimenting with this setting, particularly when you don’t wish to edit your scans. However, in most cases a wider range of unsharp masking adjustments is provided in a good image editor. (See page 7 for details.)
Advanced Adjustments High-end scanners also provide a series of additional adjustments for ďŹ ne-tuning different aspects of the image as you scan. Typically these are shown as a series of on-screen buttons in the scanner driver. Clicking on each button opens a sub-menu that lets you ďŹ ne-tune that parameter.
DIGITAL ICE technology can eliminate most dust specks and other marks from the original image (top) and produce a scan that requires minimal retouching (below). Start by gently removing as much of the dust as ZPV DBO XJUI B CMPXFS CSVTI 5IFO DIFDL UIF %VTU 3FNPWBM CPY PO UIF TDBOOFS ESJWFS *G UIF TDBOOFS comes with Digital ICE Technology, this option can be used to provide more thorough dust removal with ďŹ lm scans. However, it takes quite a bit longer than the standard dust-removal function and uses more of your computer’s resources.
The Backlight Correction tool is particularly useful with incorrectly exposed slides as it can brighten darker areas without washing out highlights. (Upper image shows original slide; lower shows the same slide after backlight correction and dust removal.) Descreening provides smoother scans of photographs in books and magazines and can also suppress the rippled patterns that can occasionally appear in subtly-shaded parts of the image, such as skin tones. However, it may also result in a loss of image sharpness – and you may not be able to restore sharpness with the Unsharp Mask setting, either on the scanner or in post-scan editing.
The Colour Restoration tool can bring faded originals (left) back to life (right).
Scanner Guide
www.photoreview.com.au Š Media Publishing 2010
Working from the left we ďŹ nd the following settings: t "VUP &YQPTVSF $MJDLJOH PO UIJT JDPO UVSOT PO UIF auto exposure function and the scanner will set exposure levels in accordance with the brightness range detected. A slider adjustment allows you to make the scans lighter or darker. t )JTUPHSBN 5IJT CVUUPO EJTQMBZT B IJTUPHSBN showing the distribution of tones in the original image. Slider adjustments are provided for tweaking the highlight, shadow and gamma levels. t 5POF $PSSFDUJPO 5IJT CVUUPO MFUT ZPV BEKVTU JNBHF tones individually. t #SJHIUOFTT $POUSBTU BOE 4BUVSBUJPO $MJDLJOH PO this button opens a dialog box with individual adjustments for each of these parameters. t $PMPVS 1BMFUUF 5IJT CVUUPO QSPWJEFT B HSBQIJDBM interface for adjusting mid-tone levels, such as skin tones, without affecting the highlight and shadow areas of the image. The user interface is shown on this page.
The Histogram lets you restore depth and a natural tonal balance to faded images.
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‘Cleaning Up’ Scanned Images Although the latest high-end scanners are good performer, many photographers prefer to ‘clean up’ their scans before printing or displaying their pictures. Most scanners will scan directly to an image editor and some are even supplied with an image editor for this purpose. :PV DBO VTF BOZ 58"*/ DPNQMJBOU TDBOOJOH program; simply open the application and select File *NQPSU BOE DIPPTF UIF TDBOOFS 5IF TDBOOFS ESJWFS opens automatically. The most popular image editors include: t "EPCF 1IPUPTIPQ BOE 1IPUPTIPQ &MFNFOUT 5IF advantage of these applications is their support for colour management and the Adobe RGB colour space, which covers a wider colour gamut than UIF AVOJWFSTBM T3(# DPMPVS TQBDF *G ZPV IBWF MPUT of pictures of landscapes to scan, either of these programs will be preferable to applications that only support sRGB.
A preview of a slide shows tones to be positioned towards the shadowed end of the luminosity range. The arrowheads below the baseline show the range of tones captured by the preview scan. Note that they fall slightly inside the full tonal range of the image. This compresses the tones in both highlights and shadows making it difďŹ cult to extract image details.
Unsharp masking
%SBHHJOH UIF BSSPXIFBET PVUXBSET UP UIF FOET PG the graph broadens the range of tones captured by the scan, giving you more image information to use when editing the digitised image. This will result in a better scan to work with.
Photoshop Elements is a popular image editor for serious photo enthusiasts that integrates well with most scanners. t "SD4PGU 1IPUP*NQSFTTJPO BOE .FEJB*NQSFTTJPO Either or both of these applications may be bundled XJUI ZPVS TDBOOFS 1IPUP*NQSFTTJPO JT B GBJSMZ basic image editor and organiser but includes tools for optimising old photographs and sharing QIPUPT .FEJB*NQSFTTJPO JT NPSF GPDVTFE PO JNBHF management and provides facilities for backing-up, geotagging and sharing images as well as quick search and tagging functions. t 5IF (*.1 JT B TPQIJTUJDBUFE GSFFXBSF FEJUPS UIBU PGGFST NBOZ PG UIF TBNF GVODUJPOT BT 1IPUPTIPQ *U T available from http://www.gimp.org/.
Unsharp masking is the tool of choice for making the edges of the various elements in digital images appear clearer and more distinct. All digitised images require a little post-capture sharpening because the digitising process, by its, nature, tends to soften the transitions between tones. Many scanners include an Unsharp Mask adjustment. However, it is usually non-adjustable so most photographers prefer to carry out additional adjustments with the Unsharp Mask ďŹ lter in their JNBHF FEJUPS *U XPSLT CFTU XIFO JU T UIF MBTU adjustment to be carried out before the edited image is saved. Three adjustments are normally provided: Amount, which is shown as a percentage, controls how much contrast is increased at the edges. Radius adjusts the width of the edges you wish to process. Small Radius settings apply adjustments to ďŹ ner detail. Threshold sets the lowest brightness level that will be adjusted and can be used to direct sharpening to only the most obvious edges, leaving the subtle transitions unchanged. *U UBLFT B MJUUMF QSBDUJDF UP LOPX IPX NVDI sharpening to apply to each image because there’s OP VOJWFSTBM ACFTU MFWFM *O NPTU DBTFT ZPV TIPVME CF guided by the image itself and by the printer you are using. Experience with your own shots and printer will be your best guide so expect to use up several sheets of paper while you ďŹ ne-tune sharpening settings to discover what looks best.
Evaluating Exposure with Histograms One of the most useful tools in any image editor is the Levels control, which displays image tones as a histogram. Histograms display all of the brightness levels in the picture as a graph that ranges from the darkest at the left to the brightest at the right. Histograms are used in scanning to show how the values of the pixels that have been captured are distributed over the scanner’s tonal sensitivity range. The horizontal axis of the graph shows the range of tones in the image with shadows to the left and highlights to the right. The height of the graph represents the number of pixels at each luminosity value.
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The image on the left is a straight scan and, consequently, a little soft. The one on the right has had Unsharp Masking applied, with the adjustments shown in the superimposed dialog box.
Scanner Guide
www.photoreview.com.au Š Media Publishing 2010
Saving Scanned Images Once you have scanned an image, it’s important to save it for future use. That means deciding the best ďŹ le format to save it in and sorting out where to store the ďŹ les.
Image File Formats *NBHF mMF GPSNBUT QSPWJEF B TUBOEBSEJTFE TZTUFN for organising and storing digital images. The most popular formats for photographs are JPEG (Joint 1IPUPHSBQIJD &YQFSUT (SPVQ BOE 5*'' 5BHHFE *NBHF File Format), although if you scan directly to an image editor you will probably also be able to save in its native ďŹ le format (*.psd in the case of Adobe applications). When deciding which ďŹ le format to use, consider the following: t +1&( DPNQSFTTFT UIF JNBHF EBUB BOE JOGPSNBUJPO JT MPTU XIFO ZPV TBWF JNBHFT BT +1&( mMFT *U T an excellent choice when you want to conserve storage space – provided you can accommodate UIF MPTT PG EBUB *U T BMTP UIF CFTU PQUJPO GPS pictures that will be shared in emails or online and those that will be printed at smaller output sizes (up to A4). However, JPEG ďŹ les suffer generational degradation when repeatedly edited and saved so it’s better to choose a different ďŹ le format for images you want to keep.
Photos scanned for printing at larger sizes or archiving should be saved as uncompressed TIFF ďŹ les.
Repurposing Scanned Images Sometimes a scanned image is required for multiple output options (print and screen viewing) but you don’t want the hassle of making separate scans. There may also be times when you’ve scanned an image at one resolution and then ďŹ nd you require a higher resolution GPS QSJOUJOH *O TVDI DBTFT POF QJFDF PG BEWJDF JT mandatory: Always scan at high resolution; it’s easy to reduce the size of a scanned photo – but you can’t increase the size or resolution of an image without reducing picture quality.
Archiving Images There are many ways to store scanned images, most of them relatively inexpensive. The easiest options are UP CVSO GPMEFST PG TDBOOFE JNBHF mMFT UP $% %7% PS Blu-ray disk and create backup copies on external hard EJTL ESJWFT )%% *O GBDU UIF TBGFTU XBZ UP BSDIJWF your digitised photos is to do both: copy the images UP B )%% BOE CVSO UIFN UP EJTLT UIBU XJMM CF LFQU somewhere safe (preferably not in the same premises). High-resolution scans can produce very large image ďŹ les, particularly when they are saved as VODPNQSFTTFE 5*''T " $% XJMM POMZ IPME BCPVU .# XIFSFBT B %7% UPQT PVU BU (# QFS TJEF Single-layer Blu-ray disks can hold 25GB of data, XIJMF EVBM MBZFS EJTLT IPME UXJDF UIBU RVBOUJUZ %7%T represent the best value at around 11 cents/gigabyte, XJUI #MV SBZ EJTLT BU SPVHIMZ DFOUT (# BOE $%T BU almost 60 cents/GB.
&YUFSOBM IBSE EJTL ESJWFT )%%T DPNCJOF convenience with high storage capacities and plugand-play interfaces that work with most computers and make it easy to move ďŹ les between machines. They are also by far the cheapest storage system currently available. However, you can only access your image ďŹ les when they’re connected to a computer and, JO BEEJUJPO )%%T IBWF B LOPXO UIPVHI WFSZ TNBMM failure rate. *U T B HPPE JEFB UP IBWF BU MFBTU UXP DPQJFT PG ZPVS NPTU WBMVBCMF JNBHFT PO EJGGFSFOU EFWJDFT :PV DPVME DPOTJEFS VTJOH BO )%% XJUI BEEJUJPOBM CBDLVQ UP optical disk.) When shopping for an external drive, consider the following factors: 1. Storage capacity. For drives that will ‘live’ on your desktop and are used for backing-up and archiving, it pays to choose the highest capacity you can afford o XJUIPVU HPJOH PWFSCPBSE %FTLUPQ ESJWFT XJUI (# 1.5GB and 2GB capacities are readily available at prices ranging from less than $100 to around $350. Lower capacities are also available, particularly in ‘portable’ drives that are powered via USB cables and small enough to ďŹ t into a pocket or laptop bag. A 320GB drive should be adequate for backing up photos taken on a typical holiday trip. 2. Interfaces. All external drives come with USB 2.0 interfaces; some also offer faster FireWire and/or SATA connectivity. The new USB 3.0 (aka. SuperSpeed 64# JT CFDPNJOH NPSF XJEFMZ BWBJMBCMF BNPOH )%%T and is starting to be offered on desktop computers UBLF VQ JT TMPXFS JO OPUFCPPLT *U DMBJNT SPVHIMZ UFO times faster data transfer speeds than USB 2.0 but is backwards compatible with earlier interfaces. :PV DBO BMTP CVZ )%%T XJUI *&&& BLB 'JSF8JSF J -*/, PS -ZOY JOUFSGBDFT UIBU BSF GBTUFS UIBO USB 2.0 but not as fast as USB 3.0. Serial ATA (SATA PS F4"5" JOUFSGBDFT BSF BMTP BWBJMBCMF PO TPNF )%%T BOE DBO PGGFS UIF GBTUFTU USBOTNJTTJPO TQFFET PG BMM *O each case, both devices must have suitable connection ports and special cables are required.
Useful URLs: IUUQ FO XJLJQFEJB PSH XJLJ *NBHF@TDBOOFS http://desktoppub.about.com/od/scannerbasics/ Scanners.htm http://www.computer-darkroom.com/tutorials/ UVUPSJBM@ @ IUN http://www.freecolormanagement.com/color/ HJNQ@OFHBUJWF@TDBOOJOH IUNM http://www.luminous-landscape.com/tutorials/ ndq.shtml http://www.photoreview.com.au/
JPEG is the ‘universal’ file format that can be opened in most software applications and viewed on every type of viewing device. It’s the best file format for saving scans that will be shared. t 5IF 5*'' GPSNBU JT NPSF nFYJCMF JU DBO CF compressed or uncompressed and compression can CF MPTTZ BOE MPTTMFTT 5*'' mMFT DBO CF TBWFE XJUI 8 bits or 16 bits per colour (red, green, blue) for 24bit and 48-bit totals, respectively. This is the best ďŹ le format for archiving important images and saving images you plan to edit later on. t 3"8 SFGFST UP B GBNJMZ PG SBX JNBHF GPSNBUT UIBU store unprocessed image data in some digital cameras. Most are speciďŹ c to a particular camera and require proprietary converters to turn them into editable ďŹ les. Scanners don’t produce raw ďŹ les.
Desktop and portable hard disk drives are ideal for storing scanned image files.
Scanner Guide
www.photoreview.com.au Š Media Publishing 2010
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