Fig. 5
From: Performance of Akatsuki/IR2 in Venus orbit: the first year
Venus dayside disk image (2.02 μm) taken from near the pericenter. a Original image acquired on October 19. b Four quadrants averaged to reduce the cloud pattern (considered as the “low-frequency” flat). c A mathematical representation of measured brightness variation as a function of distance from the image center. d Example of 2.02-μm image (acquired on April 25) with a large Venus disk. e After application of “low-frequency” flat. See text for details