Information in CRISM's 107 VNIR wavelengths (at 0.36-1.05 microns) is represented as four browse products.
The first is a false color red-green-blue (VNIR_RGB) image constructed from 590, 530, and 440 nm wavelengths, that has been stretched to optimize the dynamic range at the site shown. Thus, the stretch varies from image to image.
The second is surface brightness at 770, nm, near the peak in Mars' reflectance spectrum (VNIR_VNA). The stratch optimizes the dynamic range at the site shown, and varies from image to image.
The third false color image (VNIR_FEM) provides information related to iron minerals that spectrally dominate the VNIR range.
Channel |
Parameter |
Input/output Range for Uniform Stretch |
Significance |
Cautions |
Red |
Depth of 530-nm band; relative to a continuum between 440 and 709 nm (BD530*) |
0.002-0.219 to 0-254; 255 indicates no data |
Higher values indicate greater content or larger particle size of nanophase or some fine-grained ferric iron minerals; lower value indicates less-altered material |
Higher values also occur where the atmosphere is dusty, or where dusty atmosphere overlies shadowed slopes |
Green |
Height of inflection at 600 nm; relative to a continuum between 440 and 709 nm (SH600*) |
0.111-0.192 to 0-254; 255 indicates no data | Higher values correlated with ferric- or dust-containing coatings or rinds present on rocks, with some crystalline ferric oxides, and with olivine |
Higher values also occur in hazy atmosphere, over shaded slopes, where there is a high solar incidence angle, and over ice |
Blue |
Integrated area in 1-micron band; from 830-1023 nm, relative to a flat continuum tangent to the reflectance peak near 750 nm (BDI1000VIS*) |
0.0032-0.0307 to 0-254; 255 indicates no data | Higher values indicate greater content or larger particle size of iron minerals, especially olivine and pyroxene |
Weakly sensitive to crystalline ferric oxides |
The fourth false color image (VNIR_FM2) focuses on crystalline iron minerals detectable in the VNIR range.
Channel |
Parameter |
Input/output Range for Uniform Stretch | Significance |
Cautions |
Red |
Depth of 530-nm band; relative to a continuum between 440 and 709 nm (BD530*) |
0.002-0.219 to 0-254; 255 indicates no data |
Higher values indicate greater content or larger particle size of nanophase or some fine-grained ferric iron minerals; lower value indicates less-altered material |
Higher values also occur where the atmosphere is dusty, or where dusty atmosphere overlies shadowed slopes |
Green |
Depth of absorptions at 920 nm; relative to a continuum between 860 and 980 nm (BD920*) |
0.00015-0.02765 to 0-254; 255 indicates no data | Higher values correlated with fine-grained crystalline ferric oxides, especially hematite |
Also sensitive to low-Ca pyroxene; calibration artifacts contribute to faint striping |
Blue |
Integrated area in 1-micron band; from 830-1023 nm, relative to a flat continuum tangent to the reflectance peak near 750 nm (BDI1000VIS*) |
0.0032-0.0307 to 0-254; 255 indicates no data | Higher values indicate greater content or larger particle size of iron minerals, especially olivine and pyroxene |
Weakly sensitive to crystalline ferric oxides |