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Correspondence
Computer graphics for the microscopist
  1. Jhonel Palomino,
  2. Anders Hånell
  1. Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
  1. Correspondence to Dr Anders Hånell, Department of Neuroscience, Karolinska Institutet, Stockholm SE 171 77, Sweden; anders.hanell{at}ki.se

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Peering through the eyepiece of a microscope can reveal mesmerising sceneries, but science won’t progress unless they are shared with others. At the time of the first microscopes this could only be done by drawing images, thus requiring extensive artistic skills. Modern microscopes, on the other hand, use digital cameras, and capturing optimal micrographs instead requires a firm grasp of computer graphics. This is also needed to grasp the possibilities and potential pitfalls in digital pathology and diagnosis using image analysis algorithms.

Computer graphics describes images as either raster graphics or vector graphics.1 Raster graphics images are divided into pixels, and this format is typically used for photographs stored as JPG or TIFF files. Vector graphics instead describe the image as geometrical objects and is typically used for graphs and text in EPS or PDF files. Micrographs are stored as raster graphics, but vector graphics can be used to add annotations with unlimited resolution (figure 1).

Figure 1

(A) Raster graphics image of myelinated axons with annotations as vector graphics. (B) On magnification, the raster image is clearly pixelated while the vector graphics text remain in high resolution. (C) With the text ‘burned in’ to the image, the result is clearly inferior. (D) Anchor points (orange) and control lines (red) define the lines and Bezier curves that make up the vector graphics image of the number 5.

Even though raster and vector graphics are conceptually very different, they handle colours in the same way.2 Since computers store information in bits, where each bit is either 0 or 1, and eight bits form …

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