SUCD1, an example galaxy for testing the effect of the sky flat-field image using 12 individual frames. The pictures have a FOV of 2.4′ × 2.4′ and normal sky orientation. The flat field correction was not used for the first (left) image, but was used for the second (right) image. In both cases, the standard deviation of the background level is 0.6 ADU, total apparent magnitude 14.43 ± 0.01, and semi-major axis length 2.8″ ± 0.13.