Michael Herrmann: Image Based Measuring of Ancient Coins

Title: Image Based Measuring of Ancient Coins
(Praktikums bzw. PRIP Aufenthalts-Abschlusspräsentation)

Ancient coins are normally catalogued by photographing them from above.
In order to be able to determine their size, a ruler is usually placed
next to them in the picture. Because large collections of such images
exist, Numismatists are interested in an automated, image based way for
exactly calculating the size of a coin. An algorithm has been developed
that is able to determine the scale using the ruler in the picture. It
computes the Fourier Transformation of the image, finds the location of
the peaks in the power spectrum that correspond to the dashes on the
ruler and then uses this information to calculate the frequency and thus
the distance between the dashes. In conjunction with an already existing
algorithm for segmenting the coin, this makes it possible to calculate
the size. The implementation of both algorithms as ImageJ plugins will
be shown and their performance on real image data will be presented.