Hi Ben, Fossils
Fossils; First let me welcome you back to the fold after a long absence. I missed your reasoned comments. With Yourself and Paul Anderson back and Ben making substantial contributions, we only need Scidude and Moominaw to return to bring some more balance to the board. Thanks for your input to this thread.
Ben; I agree with you that even though the berries and cobbles and small berry-sized irregular fragments or clasts or pebbs show up blue in the Left eyed colour composites it isn't necessarily true that they are similar chemically.
Indeed, that is why I posed the implicit question in the header; Is it possible that this technique might show up some differences, besides shape, between the berries and the other similar sized objects that appear blue in the L257 colour composites?
AS Fossils implied there may be several factors interacting here that lead to different colouration of the berries and clasts between the L and R composites.
e.g.
The colour of the background
The angularity of the berry/pebb
The angle of the sunlight striking the berry/pebb
The chemical composition of the berry/hematite
The existence of living substances, eg. showing as desert varnish, on fragments
Possible differences between RAD and jpeg images
The vignetting effects in the images; etc;
Re. the colour of the background ; The first Eagle image, imo, indicates that the red colouration is taken up by practically all of the well formed "berries". Where the berries/pebbs are irregular they retain the blue colouration in the Right images. The light background might be a factor in this image but some well formed berries do show up red in the eagle images. In the sol 616 images, where the majority of the background is light, only the microberries take on a red colour. The other irregular objects either retain their blueness or take on brilliant non-red colours. Thus the berry types (the microberries) can be easily distinguished from the other objects by their taking up the red colour. In the sol 617 images, the well formed rounded berry types again take up the red colouration in the IR image both on the light and dark backgrounds. The irregular objects do not.
I think therefore that the lightness of the background may not be a determining factor in the colouration of the IR image.
Re; The sphericity or angularity of the objects imaged
The images in general seem to indicate that the rounded objects take on a red colour in the IR images while the angular objects either remain blue or take on different colours.
Re; The angle of the sunlight striking the berry/pebb
The fragments imaged from the earlier Spirit example would have been subject to similar and different sun angles (sloping pebbles) yet none took on a red colour in the IR image
Re; The chemical composition of the berry/hematite
This is also a possibility which could be falsified given miniTES and other data on the composition of the objects.
Re; The existence of living substances on fragments
Although seemingly unlikely at the present stage of the game, this is also a possibility especially in relation to the presence of "desert varnish" on the fragments.
Re; Possible differences between RAD and jpeg images
I've used RAD corrected img files from the Notebook in earlier images and compared their output with that using jpeg files of the same image. There were no apparent substantive differences in the IR colour output between the two types.
Re; The vignetting effects in the images
In the latest examples I've used crops away from areas that might have shown vignetting effects in the original images.
Fossils, I don't agree with you that we learn "little or nothing" from the photo colour differences for now. I think, Of course, that a lot more work needs to be done to calibrate any possible effect, but, imho, there is a possibility that some significant refinement of the technique might be able to indicate which objects are true "berries" as distinct from similar sized pebbs or clasts or cobbles. This putative difference might be related to unknown intrinsic differences between the berries and the other objects or it might be related to different reflective characteristics.
Winston
