Overview maps of the imaging data. Bottom to top: Göttingen FPI BB channel, blue continuum, and Ca. Left to right: speckle reconstruction, (MO)MFBD, and difference image. The display ranges for the intensity maps are 0.8 < I < 1.5 for Ca and 0.8 < I < 1.2 otherwise. The difference images are thresholded at  ±0.05. The large white rectangles denote the region shown magnified in the rightmost column, the small grey squares indicate locations with ring structures in the Ca difference image.