If your camera is not perfectly stable you will find your assembled mosaic will have a nasty `blocky' appearance as the camera sensitivity varies between sub-images. nip2 has some functions for fixing this. Select your assembled mosaic, and click on Task / Mosaic / Mosaic Balance. After a few seconds, (to quite a few minutes depending on the size of your mosaic), a new, balanced image should appear, see Figure 3.7. See the VIPS manual page for im_global_mosaic(3) for a technical explanation of how automatic balancing works.