This exquisite image of Jupiter is from Pioneer 11, the last (and the closest - 760,000 km) image to show the planet's full disk before closest approach. The image, C5 in the pioneer catalog, is a combination of a red and a blue light scan with a synthesized green. Images like this present a processing dilemma. Pioneer got an unusually good view during approach of the south polar region during approach and an even better view of the north polar region as it left. In my attempts to process these images, there appears to be a blue glow around the polar regions, perhaps due to a haze. However, since I am working from scans and not digital data and the scanned prints are of varying quality (the yellowing of the individual sheets of paper was surprisingly inconsistent) and this is near the limit of what can be discerned. Thus, figuring out if it is real is difficult. The limitations of the medium, plus the 6-bit nature of Pioneer images, makes interpreting faint features very difficult.
While I'm at it, here is image C25, taken from 2.3 million kilometers. It shows a higher phase angle than can be seen from earth. It does not one of the polar region images, but it is a pretty picture nonetheless.
Processed image Copyright Ted Stryk. Original prints scanned to create this image courtesy NASA/Ames.