LtE in CMO #273

From Timothy J PARKER

. . . . . . Subject: Re: Mars - June 14, 2003




I can't remember who it was (Damian?) that suggested, a while back, that one could make a gizmo to introduce an opposite refraction to the atmospheric refraction mechanically/optically (by tilting the eyepiece slightly), to negate the atmospheric refraction so that the imaging device has no offsets between colors. This would be particularly useful for on-chip color CCDs that use CMY and Green filters to derive color, because the red and blue both are extrapolated from the magenta filter (and therefore the refraction can't be completely removed this way). I've thought to try this out myself, but we've been socked in with the marine layer since RTMC, so I can't see Mars unless I drive to a mountain site (what's wrong with this picture?).



(17 June 2003 12:31:07 -0700)



----- Original Message ------------------------------------------------------

On Saturday, June 14, 2003, at 03:05 PM, Tom Dobbins wrote:


> David:


> Registering and combining separate images taken in rather narrow

> spectral bands should all but eliminate the effects of atmospheric

> prismatic dispersion, rather pronounced given the modest altitude of

> Mars seen from mid-northern latitudes like ours. This may account for

> the superiority of the resulting R(G)B images versus those obtained

> with the webcam used as "single-shot color" device.


> Dobby


> ----- Original Message -----

> From: David M Moore

> Sent: Saturday, June 14, 2003 3:23 PM

> Subject: Mars - June 14, 2003


> All


> Seeing was potentially good this morning, but the air is so dry

> with rapid cooling, some breezes developed just as I was setting up.

> Still I managed to get some useable images.

> I have been imaging the past several weeks using filters to

> isolate the R and B as I felt it gave a more scientifically reliable

> image set. I was still using the TouCam original color image as

> itself. I experimented this morning and used a synthesized G to make

> a color image using my original R and B images. The results look very

> promising! While I may not abandon entirely imaging in color with the

> TouCam with Mars, it would appear with this result that imaging in

> separate colors, splitting out the specific color, and combining as an

> RGB may give superior results in the individual colors as well as

> the final color image. I will continue to experiment.

> I would solicit any input.

> Thanks

> Dave Moore



Jet Propulsion Laboratory, California Institute of Technology

Mail Stop 183-501

4800 Oak Grove Drive

Pasadena, CA 91109

Research Scientist (Geologist)

Mars Exploration Rover Mission: Athena Science Team Member

Director, Regional Planetary Image Facility

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