Multiple-Scale Pattern Recognition Applied to Faint Intergranular G-band Structures |
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| Authors: | B Bovelet E Wiehr |
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| Institution: | 1.Institut für Astrophysik,G?ttingen,Germany |
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| Abstract: | Small-scale solar magnetic flux concentrations are studied in two-dimensional G-band images at very high spatial resolution
and compared with Ca ii H enhancements. Among 970 small-sized G-band intergranular structures (IgS), 45% are co-spatial with isolated locations of
Ca ii H excess and thus considered as magnetic (MIgS); they may be even twice as frequent as the known G-band bright points. The
IgS are recognized in the G-band image by a new algorithm operating in four steps: (1) A set of equidistant detection levels
yields a pattern of primary “cells”; (2) for each cell, the intrinsic intensity profile is normalized to its brightest pixel;
(3) the cell sizes are shrunk by a unitary single-intensity clip; (4) features in contact at an appropriate reference level
are merged by removal of the respective common dividing lines. Optionally, adjoining structures may be excluded from this
merging process (e.g., chains of segmented IgS), referring to the parameterized number and intensity of those pixels where enveloping feature contours
overlap. From the thus recognized IgS pattern, MIgS are then selected by their local Ca ii H contrast and their mean G-band-to-continuum brightness ratio. |
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| Keywords: | Sun: pattern recognition Intergranular magnetic features |
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