![]() ![]() The quantization step can be fixed once for all. However, the zooming factor is proportional to the renormalized smoothing scale. These parameters vary according to the total variation and the gradient amplitude of the image and therefore cannot be a priori fixed for any type of image. The image curvature microscope is a complex visualization tool dealing with three scale space parameters (1) the zooming factor (2) the quantization step of the level lines (3) the renormalized smoothing scale (the scale l at which a circle of radius r = l vanishes). Curvature values shade from red to green as follows: positive curvatures scale from red down to yellow negative ones go down from yellow to green. For better rendering, the curvature map is printed over the smoothed image and the latter is attenuated (its gray values are concentrated around 128). To avoid this phenomenon a standard extrapolation is performed by flipping the image left and right, up and down and extending it in that way by a wide band. But such junctions would create strong curvatures at the meeting points of the level lines with the image frame. One could close these lines by joining their endpoints by (e.g.) a geodesic on the image boundary. Since the curve shortening is only defined for closed curves, a rule is needed for the level lines finishing on the image border. Hence the name of curvature microscope given to the final visualization.
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