Automation of area measurement of sunspots

When drawing up a database for sunspots from a large collection of white-light films, a need for the automation of the process arises. The concepts used at the automation of the area measurements of sunspots are described. As an example, sunspot groups NOAA 5521 and 5528 are processed and the areas obtained are compared to the measurements published in the literature. Similar values are obtained, except umbral areas published by Steinegger et al. (1996) which are significantly larger than ours. We find that the differences may be attributed to the fact that the definition proposed by Steinegger et al. (1996) for the penumbra-umbra border of a sunspot is not equivalent to those used for the measurements of others of the umbral area.