SCANNING

Scanning took a back seat once digital cameras took over from film, but ten years ago most professionals had to get their film scanned. It was the zenith for film scanners, with all major camera manufacturers having a whole range of products on the market. Most people will still have film around and the only way to get negatives, trannies and prints into the digital world is to scan them. Comparing resolution and noise, the top spot went to the drum scanner (which had been operated by a real expert —I ve also seen some pretty poor drum scans over the years), closely followed by the Imacon Flextight 848 and the Nikon 8000 film scanners. The Epson Perfection V700 Photo was the representative foT a good flatbed, but despite being promoted as a film scanner it s no match for the Imacon in terms of resolution. Don t get fooled by manufacturer s dramatically high resolution figures-they apply to the stepper motor, and even if the scanner sports a dedicated lens system for film, the effective resolution is unlikely to exceed 2500dpi. A 35mm tranny or negative scanned at this resolution will give you a paltry 24MB RGB file. If scanned to, say, 100MB you re unlikely to get any more image detail. The fact that a 20MP camera will give you a respectable 60MB file made it tempting enough for me to have another go. This time I took three shots with the exposure one stop apart to cover the extreme dynamic range of this particular tranny. The repeat results were better than my first attempt, but still did not compare well with dedicated film scanners. This method might give acceptable results for film that s not too high in contrast and for low resolution scans, destined for monitor display only. A sturdy tripod is an absolute must and a macro stage for micro adjustment is almost as vital (the depth of field at 1:1 magnification is around half a millimetre). Mirror lockup and cable release are also highly recommended. Image 2 shows you the resulting shot in very high magnification (you can see about 4 mm of film), in comparison to the Imacon scan. Summary on film scanning Fine-grained transparency film was often the first choice in the days of film: accurate colour, high contrast (dynamic range 3.6 and more) and superior sharpness. It is also the easiest to scan in terms of best colour accuracy. Excessive contrast can be a problem, especially if there are lots of important image details in the deep shadows. A dedicated film scanner with a high d-max will prove its worth. The best flatbed scanners will give you reasonably good results if the dynamic range is not too high. You might also try scanning the film twice, once optimised for highlights and once for the shadows, and then combine the scans in Photoshop. The larger the film, the easier the work is for the scanner, however you need to ensure that the film is lying flat. For 35mm film you will find that a dedicated film scanner can pull out more detail if you want to print A4 size or larger. Negative film is more forgiving in difficult light situations and was/is therefore popular with photographers. In general scanning negative film is a lot more challenging —the film is more grainy and, despite the low dynamic range of around 2.4, scanners have a hard time looking through the orange mask. You need to watch out for burnt-out highlights, and negative film is also more prone to dust and scratches than transparency film. Black and white film is simple to scan, there are no problems with getting the colours right. Keep in mind that the automatic dust and scratch removal, found on some film scanners (Image Correction Enhancement or ICE), does not work with normal black and white films. It does function with chromogenic black and white films, however these are best scanned in RGB. Scanning reflective material This is the official term for what we normally do with our flatbed scanner. Printed material has a maximum (reflection) density of about 1.8 for glossy and 1.3 for matt paper. Any scanner, even the cheapest one, can handle this. In terms of resolution, a scan at 300dpi is normally fine if you want to reproduce the document or the photo the same size or smaller. If you need to enlarge a photo and if the original is sharp and has fine detail you simply scan it at higher resolution —600 or even 900dpi. Going any higher is normally useless, even if you want to enlarge a passport-sized photo to A3 —there simply is no more detail in the original and you are usually better off upsizing a 600-or 900dpi scan in Photoshop. If a scan is only used for monitor display, say a slide show, then you need to size it in terms of number of pixels, for example 1200-pixels high. Pixels per inch or file sizes in centimetres are irrelevant to monitors. There are a couple of complications you will come across when scanning photo prints, artwork or journals. One problem is when your scanner is too small for what you want to scan. The other issue comes up when you scan from a book, a brochure or a journal. The print is made up of coloured dots or rosettes that you can only make out with a loupe. It looks fine to the naked eye, but the scanner will pick up the individual dots and produce a moire pattern. The coloured dots will interfere with the monitor pixels, if not viewed at 100 per cent magnification. And they will certainly cause trouble later on in the printing process. Other issues are dirt, scratches and faded colours. These problems come up in both film and flatbed scanning. Scanning of large photos or documents In this case you need to scan in parts. I remember stitching large Al-sized maps together, scanned in sections using an A3 scanner. This was in the days before Photoshop had all those fancy Photomerge functions. The job had to be done by hand on layers. Fitting all the little rivers, roads and text labels together took me to the edge of insanity. Today, Photoshop has excellent stitching skills. From the five options on the left, Reposition will be the best choice. If you don t get a perfect fit, try Collage, which allows Photoshop to scale the individual scans a bit, in case the scanner introduced slight distortions. Make sure that the Blend Images Together box is ticked. This will iron out slight transition problems between the pieces. Again, it shouldn t be necessary, but the lighting is usually not 100 per cent uniform across the scanner bed. Here are two useful tips: firstly, always allow for a generous overlap between the individual scans. If the job can in theory be done in two parts, scan it in three parts. Photoshop will thank you by delivering perfect results. Secondly, avoid the extreme scanner edges, especially if they contain fine detail; rather trim them off and have more overlap. Scanners usually have slight distortions on the extreme borders. I learned this the hard way (maps with lots of little rivers and roads!). Scanning offset print You shouldn t have any problems with scanning photos coming from a photo lab or an inkjet printer. Once you need to digitise an illustration from a book or a catalogue you will notice moire patterns coming up on screen and the results are unpredictable. Your aim will be to smooth out the pattern to get continuous colour transitions, without reducing the image sharpness. This is always a compromise because you need to do some blurring to get rid of the pattern. Most professional and semi-professional scanners today come with software that have a built-in descreen filter. Newspaper print requires a more aggressive treatment than a high quality art print. Unfortunately, there is no fixed recipe and it often comes down to a trial and error approach to get to the best possible scan. My recommendation is to scan at high resolution and first have a go at the descreen filter in the scanner software. Later in Photoshop the traditional tool for greyscale images is the Despeckle filter (Filter > Noise > Despeckle). It has no controls, but often does a surprisingly good job for removing weird traces of patterns. The Median filter is generally better suited for colour images. A setting of no more than two or three pixels is recommended. Some of the various blur filters can do a good job, the Box Blur or the Surface Blur are especially effective for reducing moire patterns. The Smart Blur can be useful but very tricky to avoid a too-smooth, plastic-like look. In my example the Smart Blur after the Median filter did a great job because we are dealing with a cartoon here —note the sharp borders that you don t want to lose. I also found that a noise reduction treatment can do an excellent job, using either Photoshop s own tools or a third-party program like Noise Ninja. They offer great controls and also treat colour and luminance noise separately. It is important to do all this blurring before any Level or Curve adjustments. Scanning old film or photos This usually falls under the heading of photo restoration. Sometimes when scanning film you can run into severe dust problems. But it presents no problem for a film scanner with a good dust removal function, and the digital ICE of the old Nikon scanners does a particularly superb job. If you don t have access to such a scanner you need to do the cleaning manually. The Healing brush. Spot Healing brush and the Clone tool will be your main instruments. When you go through an old photo collection you often come across a film or a print with totally faded colours. Some scanning software has a function to restore faded colours but it can also be done later in Photoshop. First try the Auto function in Curves; often the original colours pop up like magic. With a good scanning technique and some skills in photo restoration you can perfectly integrate any old memories into your existing digital photo library.

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