The upper panel shows a single exposure of Comet C/2012 S1 (ISON) as seen from the Hubble WFC3/UVIS F775W filter which shows light in the reddish/infrared part of the spectrum. The image was taken on October 9, 2013.
In the below computer-processed view, the Hubble image has been divided by a computer model coma that decreases in brightness proportionally to the distance from the nucleus, as expected for a comet that is producing dust uniformly over its surface. In this image, ISON's coma does not show evidence of enhanced dust particle being released on the sunward-facing side of the comet's nucleus, as was previously seen in early epochs of Hubble Comet ISON imaging. This information adds more information about comet's shape, evolution, and spin of the solid nucleus.