Color snap-shots from Viking 1 (2)

"...Even for pictures where we have both visible and IR information, two possible types of color can be created. The character of the Sunlight reaching the Martian Surface is significantly different than that reaching Earth's surface, primarily because of scattering and absorption by suspended dust particles. In addition, a certain amount of light reflected from the yellowish brown surface finds its way back as reflected sky light.

Figures (1), (2), and (3) illustrate the range of possible color reconstructions. All three pictures are based on the same camera data. The sampling area at the Viking 1 Site is shown. Two trenches in the Sandy Flats site, the first to be dug are shown at the far left.
Figure (1) is produced by using only visible color information, making no allowance for IR leaks..." (continua)