Fig. 1 – SKYSURF sky-SB estimation algorithms are able to mask areas of an image containing light from discrete objects or bright sky gradients. The top row shows two example images in our SKYSURF database. The bottom row shows corresponding ProFound SKY maps, with the borders of Pro-med sub-regions overlaid. The bottom left ProFound map corresponds to the top left image, and similarly for the right-most images. The sub-regions used for the Pro-med algorithm are overlaid with white or red borders. Red sub-regions are identified by our algorithms as likely containing light contamination, and are masked during sky-SB estimation. We show these images to demonstrate our ability to reject areas of an image, but emphasize that images like this are rejected for sky-SB analysis because they are too crowded, as identified by the amount of red sub-regions.