Nice!!!
BTW - There is one relatively easy way of calibrating Opportunity color images that had not occured to me until today:
Steve Squires mentioned that the spherules were not blue, but actually gray. (roughly equal reflectance in every visible wavelength, as supported by this spectral
graph linked here, the "dark cobble" material)
So what I did was to pick a pretty representative bright blue spherule color in your color image. The results was 110, 172, 223. ( r, g, b ) Using those figures I multipled the green channel by roughly 0.65, and multiplied the blue channel by roughly 0.5, and the image that came out matched JPL's true-color images much better. Try it out!
(BTW, this is of course a simplistic modification, since the exposure curve is not linear, so some other conversion might be better, but the result was surprisingly good)It is kind of neat that we may have much of the calibration data we need right in front of our noses...
At least if there are spherules in the image.
What do you think?