Finishing work in and around Seitah, sols 238-378 Options

[PaulH51]

Sol 367: Raw WATSON camera image of the abrasion patch on the boulder "Sid"

Looks to be a little better cemented (when compared with some of the earlier abrasions)

I assume that may make the decision to core this target a little easier, providing the minerology / chemistry is favourable

[tau]

Sol 367 SHERLOC WATSON camera image of the abrasion with enhanced colors.
The rock contains a lot of bright elongated rectangular crystals (not to be mixed up with the radial traces of the hammering abrasion tool).

[tau]

Sol 363 SHERLOC WATSON camera image of the surface of the rock selected for abrasion. Colors slightly enhanced.
Some tiny elongated crystals about 1 mm long (if my calculation and interpretation are correct) are visible.
Sol 362 context images from Mastcam-Z and Navcam.

[PaulH51]

Sol 367: Raw WATSON camera image of the abrasion patch on the boulder "Sid"

Looks to be a little better cemented (when compared with some of the earlier abrasions)

I assume that may make the decision to core this target a little easier, providing the minerology / chemistry is favourable

Here's a 3D model of the abrasion which now has a Navajo name 'Alfalfa' LINK

[tau]

Part of the abrasion patch on the boulder "Sid", size approx. 19 x 16 mm
sol 370 SHERLOC Autofocus and Context Imager for detail
sol 367 SHERLOC WATSON camera for color (enhanced)



Edit: Added scale bar to image

[tau]

Sol 364 Mastcam-Z
1. Right eye filter 0 (RGB, slightly enhanced). Mars is apparently illuminated by two suns, note the double shadows.
However, the image is an average of two photos, one with the sun at 11:41 local mean solar time, the other one at 15:13.
2. Combination of 11:42 and 15:15 left eye filters 1 to 6, multispectral principal components. The respective brightest false color RGB (at 11:42 or at 15:15) was used for this image.
3. Combination of 11:42 and 15:15 right eye infrared filters 1 to 6, first and second principal components only. The respective brightest RGB was used.
Compact rocks appear bluish-gray, vesicular rocks orange-brown in infrared false colors, an indication of possibly different chemistry/mineralogy.
4. 11:41 anaglyph

1 . . 2 . . 3 . . 4

[Bill Harris]

"vesicular rocks orange-brown in infrared false colors, an indication of possibly different chemistry/mineralogy."
Or a higher degree of weathering, which is chemistry.

One thing I notice in your processing of these photos in this area is that their top "airfall coating" is very light, almost white in IR. It'll be interesting to look at that chemistry.

--Bill

[Bill Harris]

Part of the abrasion patch on the boulder "Sid", size approx. 19 x 16 mm
sol 370 SHERLOC Autofocus and Context Imager for detail
sol 367 SHERLOC WATSON camera for color (enhanced)

That rectangular to the right of center: my initial impression is that this shows lamellae (albite?) twinning. It'll be interesting to see the returned core.

--Bill

[Phil Stooke]

A new name from an LPSC talk by Sholes et al., (abstract 2641) - the name is not in the abstract. The gap in the delta scarp which Perseverance will follow to climb onto the delta is now called Hawksbill Gap. Also a Seitah-like patch NE of Seitah and east of the delta is called Gaspé.

Phil

[tau]

... One thing I notice in your processing of these photos in this area is that their top "airfall coating" is very light, almost white in IR. It'll be interesting to look at that chemistry. ...

The "top airfall coating" is most likely orange-brown dust, and it appears featureless white or very bright in my images due to clipped highlights in the Mastcam-Z raw images that I used.
This clipping exists in all Mastcam-Z gray-scale raw images of filters 1 to 6 and in the red channel of filter 0 (RGB), where the clipped areas have the value 254.
The "raw images" are obviously not raw in the sense of digital photography, where "raw" means straight out of the camera and not jpeg-ed.
Because calibrated images from sol 364 are not yet available, here is an example from Sol 69 with the upper part of Kodiak hill:

1. Mastcam-Z right eye filter 1 (infrared) image from NASA's "Raw Images" site (link), with 8 bit per pixel, no details visible in the brightest part
2. Same as 1, all pixels with a value 254 are marked red
3. Calibrated image from the Planetary Data System Imaging Node with 16 bit per pixel, (link)
4. Same as 3, brightness adjusted
5. Same as 3, histogram adjusted to show the details in the brightest part on top of Kodiak hill

[Phil Stooke]

A new drill hole at Sid, sol 371.

This is a composite of two images to cover a dropout.

Phil

[mcaplinger]

The "raw images" are obviously not raw in the sense of digital photography, where "raw" means straight out of the camera and not jpeg-ed.

Agreed that "raw images" is something of a misnomer, but I'm not sure what you show has anything to do with JPEG. It's not uncommon for MCZ images to be sent with only lossless compression, which is as raw as it comes. I think the saturation problem you show is more due to the images having been stretched/contrast-enhanced. The vast majority of MCZ images are autoexposed and really shouldn't need to be stretched, and I have no idea what algorithm the raw image website is using.

[fredk]

Indeed, and since the "raw" images are available as pngs, jpegging shouldn't come into it at all for those lossless images.

Another possible source of clipping is bit depth reduction. Depending on the autoexposure algorithm, it's possible (though perhaps unlikely) that the pixels thrown into the 255 bin have a range of (unsaturated) pixel values at the native bit depth.

[mcaplinger]

Another possible source of clipping is bit depth reduction. Depending on the autoexposure algorithm, it's possible (though perhaps unlikely) that the pixels thrown into the 255 bin have a range of (unsaturated) pixel values at the native bit depth.

Not sure what you're suggesting. There is a 12-bit ADC in the camera but the "native bit depth" is effectively 8 bits because pixels always pass through a 12-to-8-bit companding table. The sensor saturation level is typically well below 255. The autoexposure algorithm is usually set to so that no more than 2-10% of an image's pixels exceed saturation, although sometimes the level and/or the fraction are tweaked depending on the scene (you can see these settings in the PDS product.)

If something is saturated on the raw images site and not saturated in PDS form, I can only blame the raw image stretching for that.

[fredk]

Thanks - I forgot about the companding.

So in Tau's image 3 above, it's not that the image is 16 bits per pixel, but simply that it's unstretched, that enables you to see detail in the bright regions.