Example of a raw image reduction for an ANDICAM J-band image. Top row (left to right): single raw image of SN 2019so, master dark, and dark-reduced raw image using the two previous images and a master flat. Middle row: flat and dark-reduced image, detected cosmic rays, cosmic-ray-corrected image, and quadrant background level. Bottom row: image corrected for quadrant features, sky image, and sky-subtracted image. The sky image was evaluated from the remaining set of dithered images taken on the same night. The host galaxy was masked out for each single image when we constructed the sky image.