Photometry measurement method for the stellar stream around NGC 922. The apertures where the photometry parameters, surface brightness, and colours are measured both for the ‘shell’ and the ‘tail’ parts of the stream are highlighted in red. The polygonal apertures (green) indicate the parts of the image used to measure the magnitude of the stream. The contour of the detection, encompassing the galaxy and the stream, is highlighted by a black line. Here the input image has been warped to a pixel grid 8×8 coarser than the original one, to highlight the low surface brightness signal.