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An acquired taste by Tim Daly, from Ag29 |
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Optical and interpolated: Just to confuse things further, scanner resolution is often quoted in two distinctly different values: optical and interpolated. The optical value gives a true hardware specification, that is the actual number of sensor cells your scanner is fitted with. An interpolated value, however, indicates how much your image can be enlarged by software trickery. Remember that with an interpolated image, extra pixels are squeezed in between the originally detected ones with a colour value ‘guessed at’ by averaging the colours of adjoining pixels. These interpolated images by their very nature can never have the same sharpness or quality as optical scans, so even if your scanner can ‘capture’ at 13,000ppi, images won’t be as pin sharp, only bigger. Interpolated images are just like enlarged photocopies, bigger but at the expense of clarity. Scanner software: At the heart of the scanner operation is the scanning software. All scanners are bundled with two types of software: either a small standalone application or a Photoshop plug-in. Standalone software can be operated independently of an imaging application such as Photoshop and will take up much less of your computer’s memory resources. For repeated use or batch scanning, this will allow a faster transfer of images to your PC. The other alternative is the plug-in, enabling you to operate the device and the same scanning application from within a compatible application such as PaintShop Pro or Adobe Photoshop. Once the scanner’s software plug-in has been installed in an applications plug-in folder, the device can be found via the File>Import>Plug-in menu. With a plug-in, once an image is captured, scanning software closes automatically and you are left in Photoshop to manipulate your image instantly. Another variation on the plug-in comes through the universal TWAIN. TWAIN, bizarrely, stands for Toolkit Without An Interesting Name and it works essentially like a software ‘travel plug’ by allowing many different third-party devices to interface with Adobe Photoshop and any other TWAIN-compliant applications. Next Page >> |
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• With black and white negatives, actual film exposure can present difficulties. In this example a thin negative was scanned as follows: top left: no adjustment; top right: Auto ‘exposure’; bottom left: modified with the crude brightness slider; bottom right: same as bottom left but in the opposite direction. © Tim Daly Page 4 0f 6 |
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