Left: detrended VIS image of the Perseus cluster. This image follows the ERO mask, overscan, bias, flat-field, and deepCR corrections revealing a checkerboard pattern in a small number of quadrants, which is noticeable through the subtle relative jumps of the background level between adjacent quadrants. The effect is 2% of the background for the two most affected quadrants (if left uncorrected this would leave residuals at the 27 to 28th mag arcsec⁻² level). Right: final image after applying a low-flux nonlinearity correction to approximately 30 quadrants. The image now displays uniform flatness of the background across all borders – both between detectors and within quadrants – indicating reliable photometry for extended emission such as galaxy stellar halos, intra-cluster light, and Galactic cirrus, as showcased here. The limiting surface brightness of these single frames exceeds 29 mag arcsec⁻² throughout the entire FoV (direct detection of faint contrasts at the 10ʺ scale).