4 ms·

Amazing! I wonder if the colors are real or if they are inserted afterwards.

• ceejayoz 9y ago
  Per https://www.popsci.com/bigpic-europa-close-true-color https://www.popsci.com/bigpic-europa-close-true-color, pretty close to real colors.
• hliyan 9y ago
  I've always wondered this same thing ever since I was fascinated as a child by the lurid green photographs of Ganymede (Jupiter) and Enceladus (Saturn) from Voyager 2, only to later discover that they're false color images.
• deleted 9y ago
  [deleted]
• gmueckl 9y ago
  The colors are a reconstruction. As far as I remember, no camera on Galileo had a set of color filters that would approximate human vision. They each had a set of selectable color filters on a wheel, which had very narrow spectral ranges, some even outside the human visual range. These filters were selected for scientific reasons (e.g. exploit spectral bands where certain materials have a particularly low or high reflectivity to help identify them). Any color images you see from this and similar missions are reconstructions: a full color image would need to be taken with the whole spectrum from about 400nm to 700nm, which is much wider than the color filers that are available. So what you see is based on some kind of reconstruction of the parts of the visual spectrum that is missing in the source data. I do not know how far you can take the reconstruction in practice. If you know the source illumination (it's the sun - easy), identify all the materials that are in the images successfully (hard) and know their reflection spectra (possible), you can in theory create realistic color impressions.