Further, the absence of a zoom objective may limit the optimal use of the number of pixels, particularly if the relevant area is small compared to the area covered by the camera. In this case a dedicated slide scanner, with a higher resolution (at least 2000 dpi) has to be used.Ī disadvantage of a CCD camera is the limited, and in most cases fixed, number of pixels, e.g., 768 × 480. Negatives and slides with a size of 24×36 mm can also be transferred into computer images, although an ordinary flatbed scanner with a hardware resolution of 300 or 600 dpi is inappropriate for scanning slides! Although flatbed scanners are supplied with software to increase the resolution of scanned images to 4800 or even 9600 dpi by applying optimisation and interpolation techniques, the results are very poor, at least for the goals of this chapter. In most cases the resolution can be adapted to optimise file sizes in the computer. It also leaves some room to adapt the scanned area. This is an image size that can be processed by modern computers and gives very good results. This means that for a set of patterns with a total size of 10×15 cm (or about 4×6 inches), the computer image is about 1200 × 1800 pixels.

Most modern flatbed scanners have a maximum resolution of at least 300 dpi and also at least 256 grey tones. When the patterns are reproduced on films or autoradiograms, the scanner should be extended with a transparency adapter in order to obtain the best results.

Resolution of the scanned imagesĪ flatbed scanner can be used to scan polaroid photographs of a gel. John Hauman, in New Approaches for the Generation and Analysis of Microbial Typing Data, 2001 A. Setting-Up Intra- and Inter-Laboratory Databases of Electrophoretic Profiles

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