Images illustrating the multi-scale composition of the background map on a sub-image within Field 1. From the top left and going anticlockwise, the five panels show: the sub-image with the spikes removed; the background map at 100-pixel scale including the global mean; the previous map with the addition of the 40-pixel scale background; the previous map with the addition of the 25-pixel scale background; and the residual image obtained by subtracting the multiscale background from the original image. The color scale ranges from 0.35 to 0.95 MJy/sr except for the top-right panel, where it ranges from −0.05 to 0.05 MJy/sr. A nonlinear color scaling is used to enhance the low-surface-brightness features in the field.