Wikipedia:Reference desk/Archives/Science/2026 February 23

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February 23

Request for image processing.

Hello. Can I request someone to please process these filtered images of Io into natural color or something close? They were taken by Galileo if you need the meta info. Big thanks.

IapetusCallistus (talk) 15:57, 23 February 2026 (UTC)

Process with what desired result?  Card Zero  (talk) 16:26, 23 February 2026 (UTC)

Natural color, or something close to it. I'll rephrase my original post. IapetusCallistus (talk) 16:30, 23 February 2026 (UTC)

Is the fourth filter infrared?  Card Zero  (talk) 17:18, 23 February 2026 (UTC)

Yes. Green - 559 nm | Red - 665 nm | Violet - 413 nm | Near-Infrared - 756 nm IapetusCallistus (talk) 17:24, 23 February 2026 (UTC)

highest resolution true color, but maybe not the correct view for OP

False color can convey more information to our poor little eyes

(ec)I believe these search parameters from SETI's "Outer Planets Unified Search Tool" are the source of your mosaic? Four observations from Galileo's Solid State Imager, the top four grayscale raw data previews and the bottom four color previews? The OPUS interface is not very intuitive, but one can get to the observation details from the "Browse Results" tab, selecting an image, then paging through the results. There is a "More Options" menu in the lower right corner of the with a "Show Detail" entry which leads to the "Detail" tab:

• go-ssi-c0349746300 1996-06-27T04:00:46.048 0.51-0.61 microns
• go-ssi-c0349746313 1996-06-27T04:00:54.715 0.62-0.73 microns
• go-ssi-c0349746326 1996-06-27T04:01:03.381 0.36-0.44 microns
• go-ssi-c0349746336 1996-06-27T04:01:12.048 0.75-0.79 microns

I don't doubt that someone here is capable of aligning and creating a true color approximation/pseudo color image, but looks like a lot of work. I'd think someone has already done that work for these observations. Here for instance is 3 July 1999 true color from the highest resolution images. fiveby(zero) 17:32, 23 February 2026 (UTC)

Is the first image here the same observation (flipped verticallyrotated 180)? June 27, 1996, but no link to source. fiveby(zero) 18:05, 23 February 2026 (UTC)

The images are not even at the same scale. The purple one is larger by about 7%.  ​‑‑Lambiam 18:12, 24 February 2026 (UTC)

looks like the 27 June 1996 observation, but can't find NASA source for this image

"Natural colo[u]r" is somewhat conjectural, since the strength of sunlight at Jupiter is a little less than 4% of that at Earth (outside the atmosphere), so the colour response of the Mark 1 eyeball may not be quite the same. Also, if you were looking at Io from the apparent distance the photos suggest with your literally naked eye, you would have other things to worry about than its colour. {The poster formerly known as 87.81.230.195} ~2026-76101-8 (talk) 19:49, 23 February 2026 (UTC)

See also Color appearance. Shantavira|^{feed me} 10:10, 24 February 2026 (UTC)

What a treat it would be to experience our world in false color! fiveby(zero) 13:59, 24 February 2026 (UTC)

.  ​‑‑Lambiam 17:26, 24 February 2026 (UTC)

To enhance my ability to appreciate the forms of nature—not limit it. Over course, the other way often works also. fiveby(zero) 17:52, 24 February 2026 (UTC)

Something akin to this is having a cataract replacement operation. Lenses developing cataracts add a yellow tint (i.e. a blue filter) to vision, which because of its gradual onset is often unnoted by the subject. New lenses render everything suddenly bluer, and some lenses also pass more ultraviolet (which the retina is somewhat sensitive to) than natural lenses.

I once met the amateur Solar spectroscopist Commander Henry Hatfield, well-known in astronomical circles, who had just had one lens replaced and who said the contrast was striking and interesting, particularly with regard to his speciality. {The poster formerly known as 87.81.230.195} ~2026-76101-8 (talk) 19:32, 27 February 2026 (UTC)

I don't know a source for the RGB values of monochromatic light at different wavelengths. I assume though that the OPUS colouring was chosen to approximate the colours at the wavelengths of each filter. After rescaling the four coloured images so that they are all the same size, I tried two things:

1. computing, per pixel, the average R, G and B values;
2. computing, per pixel, the sums of the R, G and B values, and multiplying at the end these sums by a factor so that the highest result was equal to 255.

These two procedures resulted in identical images, which must be the result of how the people behind OPUS decided to add colour to each separate one of these four images. The result can be seen here. (If I didn't know this is Io, by the colours I might mistake it for a nice and round potato against a black background.)  ​‑‑Lambiam 19:10, 24 February 2026 (UTC)

Had some probably on target links and papers open yesterday, but didn't think anyone was going to actually do this. If i recall some were not using the visible red filter data, but green, violet, and infrared for some reason. I imagine it would be modeling the structures of the eye as filters and playing with the responses? They stuck MarsDials on the rovers to and occasionally take pictures of that. There was a group doing post mission color calibration of the Galileo images, but i can't find the link again. fiveby(zero) 19:52, 24 February 2026 (UTC)

• True or False (Color): The Art of Extraterrestrial Photography - Universe Today
• The Galileo Solid-State Imaging experiment
• Global Color Variations on Io
• Astropedia - Io Galileo SSI Global Color Merge Mosaic 1km

@Lambiam Can I use your work for Kanlaon Patera (English) and Kanlaon Patera? IapetusCallistus (talk) 20:01, 24 February 2026 (UTC)

As a creator I'm happy to put this in the public domain, but for use in a Wikipedia article there is this issue of WP:OR. I revealed exactly what I did, but I don't know how this relates to the real true colour situation.  ​‑‑Lambiam 22:58, 24 February 2026 (UTC)