ABSTRACT
Ever since Chapter 3, we are aware that images consist of 2D or 3D image elements. These elements are, by their nature, discrete. A change in image size therefore introduces artifacts, which may be considered rounding errors. Figure 7.1 gives an illustration. The original image is a PET-scan with 128× 128 pixels in-plane resolution of a gynecological tumor located in the pelvis. The left part of the image was resized without interpolation – the single pixels appear blocky and enlarged. If we apply an interpolation procedure, which distributes the pixel intensities in a more sophisticated manner, we get the result on the right hand side. In short, enlarging the image consists of putting a finer mesh of image elements on the image data. If we don’t distribute the image intensities in a smooth manner, a blocky appearance is inevitable. It is to be emphasized that interpolation does not add image information, but improves visualization of image data.
