The LEDs become very dim at distances of more than a few centimeters (inverse-square law). You could potentially take an image of something like the RSM with the LEDs and a long-enough exposure, but I question if it would be that interesting.

Yeah - it would take some very long exposures ( and thus pretty noisy images probably ) - and also there's the energy penalty of heating the actuators at night to do it as well.

It also might get a little creepy

A comparison of the Mastcam 100 and MAHLI images of the newly-drilled hole at 'Cumberland' site, taken on the same day (Sol 279).



Further to my posts earlier in this thread, I'd like to draw attention to the difference in colour balance between these two images. The Mastcam image has a noticeable yellow/orange cast to it, while the MAHLI image seems to be closer to the true (white-balanced) colours. People have been insisting that there is no difference between the two cameras, yet the difference in the resulting images is apparent to me.

Original images: http://mars.jpl.nasa.gov/msl-raw-images/ms...0000E1_DXXX.jpg
http://mars.jpl.nasa.gov/msl-raw-images/ms...1000E1_DXXX.jpg

Who's insisting that? Not me, see post #270 in this thread. There are (IMHO, minor) differences in color and I have explained why.

Those images are probably not the best comparison, since the turret will be blocking part of the sky in the MH images. That should shift those images towards the blue (sky is redder than sun). Still, I'd say this likely won't account for all of the difference.

A better comparison would be views of the distant landscape with MH and mastcam, from the same location and close to the same time of day, if you could find such a pair.

Curiosity's self-portraits (taken with MAHLI) provide a good view of the surrounding terrain. For example, see the raw images from s85. MAHLI: http://mars.jpl.nasa.gov/msl/multimedia/ra...mp;camera=MAHLI and Mastcam: http://mars.jpl.nasa.gov/msl/multimedia/ra...mp;camera=MAST_
MAHLI shows a gentle light-brown terrain, and the white surfaces of the rover as white.

Comparison of the view of the distant Mt Sharp, from Mastcam (s271) and MAHLI (s85):

Almost 200 sols apart - 1/3rd of a martian year - we know there to be dramatic differences in the Tau - those images SHOULDN'T look the same.

Quite. Also, we acknowledge that the uncorrected color between MAHLI and Mastcam is slightly different. wildespace, you can stop making this point. The PDS delivery will have color-corrected versions of all images, and then you can argue about those if you wish.

But at the end, of what are we arguing about ? Some little variations of white balance ? Saturation ? What else ?

This is exactly the same as bring a groupe of personn to visit the Great Canyon, taking some pictures, and view their picture on the Internet later when they share it to each other. Some will look a little bit too blue-ish or too yellow-ish. But at the end, this will be the same landscape to be pictured, and that's all that count.

According to this LPSC 2012 paper Mastcam is more sensitive to red near 676nm than MAHLI according to this MSL Science Corner article.
If you compare the two camera sensitivity spectra to red with the human L type cone monochromatic spectral stimulus (human eye red sensors), you may see, that it's closer to the MAHLI sensitivity for red (no peak near 676nm). Therefore the closer similarity of MAHLI raw images to natural colors.
This as a hopefully plausible and detailed explanation for the color shift, besides different observation conditions.

A possible benefit by differencing the two images to simulate a far red filter can be retrieved more easily by applying the L4 filter, to my eyes.

This is why I never do anything with color!

Phil

What makes you say MH is closer to natural? What does that even mean? Is your monitor carefully calibrated? Do we know what to expect, given the red sky illumination - i.e., shouldn't white parts of the rover appear yellow/redish? Etc, etc.

All we can do is look at the calibrated MER colour imagery, and wait for corrected MSL images...

I'm a coauthor on the LPSC abstract and you can't really get that level of detail out of those figures IMHO.

There's no debate that there are slight color differences between the cameras. They are not intentional. We didn't do anything to explicitly balance the colors; the raw images are just what's coming out of the camera. The differences are caused by the spectral transmissions of the lenses and the slightly different bandpasses of the IR cut filters. I spent quite a bit of time on the color-corrected archive products, which have been delivered to PDS, but I don't know when they will be released. And there will still be some uncertainty about what "color-corrected" means; I tried to be explicit in the documentation about exactly what the processing entailed, but radiometry is complicated and these instruments are cameras, not colorimeters or spectrometers.

Sorry if I upset or aggravated anyone here. My main intent behind this discussion is what would Mars appear like to the human eye. I know that our eyes get adjusted to any prevalent colouration, doing a sort of "white-balancing" themselves. If you take a RAW image in incandescent lighting using a DSLR, the image will come out unnaturally red because, unlike our eyes, the camera didn't adjust itself to the scene. Likewise, the raw Mastcam images come out with the prevalent yellow/orange cast to them (also affecting the white surfaces of the rover and the grey exposed rock), because of the dusty atmosphere. Which is why I was pleasantly surprised to see that MAHLI images show the (more or less) white rover, grey exposed rock, and much more subdued hues of the landscape and the sky. Call my conclusion unbased, but like Gerald I think that MAHLI images are closer to what the human eye would see on Mars.

Anyhoo, looking forward to the PDS.