Mars.
Processed, leveled, cropped MCZ_LEFT, FL: 110mm
Sol: 880, RMC: 43.0000, LMST: 12:07:17
Original: https://mars.nasa.gov/mars2020-raw-images/pub/ods/surface/sol/00880/ids/edr/browse/zcam/ZL0_0880_0745060589_769EBY_N0430000ZCAM08882_1100LMJ01.png
Credit: #NASA/JPL-Caltech/ASU/65dBnoise
"There's more than one way to skin a cat"
The first image is part of an Arizona State University panorama composed from images captured on #Mars2020 Sol 4, "approximately simulating the colors of the scene that we would see if we were there viewing it ourselves."
https://mastcamz.asu.edu/galleries/mastcam-zs-first-high-resolution-mosaic-sol-4/?back=%2Fmars-images%2Fpanoramas-mosaics%2F%3Fitem_type%3D360-panoramas
The second image is the same but filtered for people with insensitivity to green.
When it comes to color perception or other sensory experience, things don't necessarily follow our preconceptions 😀
[Note: The banner image here is a lower-resolution MP4 movie file, and the JPEG available at the red button link below is a 1/3 resolution version. For full-resolution versions of this Mastcam-Z mosaic, click on the TIFF or PNG button below, and for additional versions of this panorama at full resolution, including 3-D anaglyphs for […]
Colour perception varies more than most people realise.
I guess the folk that set up some of the M20 cameras and their image pipelines appreciate the raw images on the mission server more than others.
@stim3on @PaulHammond51
My concern here is visual perception of Martian terrain and how a viewer can make the most out of it. So I take a "high altitude" view on the subject, caring most for the end result.
Anyone who has ever dived deeper than 10m (or has seen pictures/movies) knows that everything at that depth looks blue-green, despite fish and corals still being colorful. If one needs to understand what goes on at the bottom of the sea, presenting one ...
1/4
with an accurately calibrated picture does not help; most creatures, plants and other details will go unnoticed in a homogeneous color.
Same with Mars. I've seen numerous attempts to process Martian images "as one would see them if one were on Mars", most of them based on a preconception of a "red planet" giving a red/orange tint to everything. I doubt most such attempts are any close to what one would actually *perceive* when being/living there. Instead, most such attempts reduce ...
2/4
significantly visual perception: details get washed out in the amplified orange/red colors, overall perceived contrast gets reduced, things look completely unnatural, alien. The animal inside a human perceives a world artificially worsen for the sake of a preconception of how things "could|should|might" appear.
While doing that might be useful to a movie director, it is certainly NOT good if one tries to understand what goes on there. It's not an accident that almost all instruments ...
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scientists (and everyone else) use are made to improve perception of the object/process being observed. The objective is always to augment human perception with details hard to discern otherwise.
I believe that NASA follows the above as close as possible. When the task is to preserve color fidelity, they do that using calibration targets for each instrument, and other procedures pertinent to the task.
It's inconceivable to me that they don't make use of those facilities.
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Attached: 2 images @[email protected] yeah pretty crazy with all the wildfires! I'm curious though if you have seen the smoke yourself, did you notice your eyes adjusting to the overall reddish lighting? We had lots of Sahara dust blown over to Germany to while ago and it also tinted the sky very orange. However, after a while of being outside my eyes adjusted to it and it nearly looked like a "normal" overcast day. The left image is with daylight whitebalance and the right one roughly how I perceived it.
@65dBnoise And yeah, most such attempts are basically just "winging" it and are not based on physical properties.
While the NASA images are technically based on physical properties of the cameras, they completely ignore the correct mapping of those values to a display. In that way they are not much more useful in creating an authentic view than the approximated hobbyist attempts.
@65dBnoise Even though the rovers have color calibration targets, I have not seen a single paper that uses these to calculate a correction for accurate colors. In principle they could be used for this, but they are far from optimal because there are too few targets with too little variation.
That said, they are actually used for calibration processes, but none that concern color accuracy. They are only used to calibrate radiometric data, i.e. how much light energy is entering the camera.
@65dBnoise The "natural color" images can also be useful for some things, but they don't help with creating a view that is useful for visual interpretation. Also, calling them "how the human eye perceives it" is objectively and physically wrong.
In that way there seems to be a misconception with certain NASA folks on how our color vision works.
@stim3on
Hm, I'm afraid I wouldn't know, since I'm by no means an expert.
I would expect the PDS to have calibrated images using well established procedures tailored to the purpose they are using them for, which is the most important criterion for them to spend time to meet. There are other areas where similar criteria apply, and it might make it appear as if they didn't care.
Not sure if the purpose of the (~live) pipeline, where we get the raw images from, is to provide calibrated images.
@65dBnoise the PDS data are calibrated for radiometric accuracy. And as far as I know they are doing this really well.
The problem seems to start outside when people (and the above mentioned LPSC abstract) expect the "natural color" images (which basically are contrast enhanced radiometric images) to also show correct colors which they definitely don't.
There are no color calibrated products for Mastcam mentioned in the PDS, as far as I know proper ones don't exist at all.
@stim3on
Oh yeah, I'm also annoyed by green Mars, and especially by sinking horizons, as I've made sure we all know by now 🙃 😆
But having managed projects with clearly defined scope of work and deliverables for which one has to spend one's time, resources and effort, where time is of the essence, I very well understand why such annoyances (to others) may happen. :)
@stim3on
Yes, I remember that post of yours.
I'm sure when the time comes for humans to go to Mars, or rather long before that time comes, a lot of research is going to go into such matters for very practical reasons, as the outcome will directly affect the life and work of those that will make the trip. Sure, we'll also have their first impressions about colors, but if naturally filtered color proves to be a problem to visual perception, that will change with the use of visors etc.
@65dBnoise I highly doubt that it will be a problem, just because our eyes are so capable of adjusting to different lighting situations.
On a clear day Mars light isn't even that much redder than earth light. After all, it's the same sun that illuminates us here on Earth.
Again, this paper compares the both:
https://doi.org/10.1029/2020EA001336
It's only during heavy dust storms when the sun is partially hidden when color perception may get a little funky.
65dBnoise
Paul Hammond
Simeon Schmauß