[X] My Assistant

[Harkeppler]

Combination of the infrared images of Sol 616 with R4 (red), R5 (green) and R6 (blue) give as a pseudocolor photo after some color enhancement an interesting result:

the blue-gray sharpe edged small stones (probably some vulcanic material) found strawn around the Erebus site look quite different in infrared but not in the visual band. There are at least three destinct infrared signatures giving probably a hint on their origin and chemical composition.

Here, on the left an R2 (red), R1 (blue)-picture is shown with synthetic green chanal according to the visual color taken from an L4L5L6 image and on the right the R4R5R6 picture.

The original Opportunity photos were normalized using a circular mask to reduce the radial loss of brightness to the edges.

This pair can be seen on the right (I am wondering that the thumbnails are not shown in the correct sequence).

The second image couple shows Bounce at Sol 68 in L4L5L6, L2L7 and R2R1 (from left to right with synthetic green in L2L7 and R2R1) for comparison: There is a possibility to make nearly natural looking color composites using the R2 and R1 channels.

This image triple is shown on the left.

(Image processing was done by collegue Mr. Norbert Gasch)

The interesting question is now: Does anyone have an idea what sorts of material this can be at the Erebus site?

Best wishes: Harald

Attached thumbnail(s)

 

[CosmicRocker]

To be fair, I don't think Harkeppler or anyone else made an outrageous claim here. In spite of the jpeg stretching, the lack of calibrations, etc... it seems perfectly reasonable to expect that relative spectral differences could be interpreted as differences in mineralogy within this image.

What is most interesting now is the fact that edstrick's work did not reproduce anything similar. I'd like to better understand why that is the case.

[helvick]

To be fair, I don't think Harkeppler or anyone else made an outrageous claim here. 

Yep, gotta agree. Harald made a decent effort to check something out in a methodical way and I wouldn't want him to think we were a bunch of arrogant wags having a go at his efforts. It was a good question just unfortunately based on untrustworthy data.

Since I made the same erroneous assumption myself in the past I have to say it's not obvious at all that the image data is modified before it's put online. It's glaringly obvious as soon as you try to do anything serious with them.

[Harkeppler]

Maybe some remarks are allowed:


The photos used are relatively new and no radiometric data are available at this time. So, everything I try to say is, that there is a relativ (!) but distinctive difference in the spectral reflectance.

to: edstrick

I have made a second attempt with R3 R4 R5 to document the process:

Left: after making a composite with R3 = red, R4 = green and R5 = blue

You can attribute other colors too, this is not a problem. The color diference can be seen here, I assume.

Right: after increasing only the saturation the things come out clearly. This picture can be processed further but I have not done here.

But have a look that most people can distinguish red hues better than blue ones.

to: tfisher:

>I propose a simpler explanation. The sun changed angles enough that different surfaces of the angular pebbles are brightly illuminated in the different exposures<

No, that is not the explanation because several pebbles look different. The sun angle effect should be the same on each.

to: djellison:

>You're using the JPG's from Erebus I assume - and that's a fundamental barrier in making any spectral claims. It can not be done. You can fudge them to make pretty pictures, you can measure how far things are apart, but you can NOT under any circumstances, using any magical technique, use the raw JPG's to make any claims as to the spectral properties - even in just a relative sense - of anything imaged<

Yes, Erebus Sol 616. The fundamental barrier is the result of the problem that JPL is handing out photos without radiometric data on time to bypass the freedom of information act and to reserve the complete data set to their scientist and their affilates. The freedom of informaion act only considered the photos theirself. Funny legal situation.

HK

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[djellison]

he fundamental barrier is the result of the problem that JPL is handing out photos without radiometric data on time to bypass the freedom of information act and to reserve the complete data set to their scientist and their affilates. The freedom of informaion act only considered the photos theirself. Funny legal situation.

Nothing to do with FoI at all. It's bog-standard-science-mission-practice - release science data six months down the line so the people who made it happen get first dibs at it. That we're getting the quick-look-rough-and-ready-jpg's is an enormous bonus.

Doug

[clt510]

Nothing to do with FoI at all.  It's bog-standard-science-mission-practice - release science data six months down the line so the people who made it happen get first dibs at it.  That we're getting the quick-look-rough-and-ready-jpg's is an enormous bonus.

Doug

Exactly right, Doug. I'm involved in a large-scale experiment which has (with government approval) a two year moratorium on release of the raw data. The NASA/JPL guys are amazingly open about how much information they are willing to share immediately. It makes perfect sense to me to withhold a portion of the "best data". The people who have worked around the clock getting the mission to this point deserve all of the credit in the world, and certainly deserve first crack at their data.

If you want to contrast and compare, go over to the Mars Express website. You mostly just get PR blurbs on that site....