The raw images (available on request) have been captured using a Canon 8-15mm fisheye lens and therefore they have a wide field of view, which results in a dark image boundary as the lights did not illuminate the outer sectors well. The images in this dataset have then been undistorted to virtual images that an ideal perspective camera with only 90 degrees horizontal field of view would have seen from the same position. To achieve this, the color of each pixel in the ideal image is obtained by - computing the ray in space associated with this virtual pixel (using rectilinear un-projection) - projecting this ray into the original fisheye image (using equidistant projection), yielding a sub-pixel position - interpolating the colors of the neighboring pixels Technically, the undistortion has been performed using the tool https://svn.geomar.de/dsm-general/trunk/src/BIAS/Tools/biasproject.cpp (at revision 418, and earlier, compatible revisions). Manual image annotation is available here: https://annotate.geomar.de/volumes/250