Illustration of the main preprocessing steps on a g band image cutout. Top-left: original full-resolution image. Top-center: image after the 4 ×4 pixel binning. Top-right: corrected for background oversubtraction near bright objects (spiral galaxy at the center) and set anomalies, such as vertical stripes, to zero. Bottom-left: small objects replaced with nearby background noise. Bottom-right: MW stars replaced with the local background.