Spectral differences of surface materials are often mapped by using the       
ratios of various spectral bands to bring out diagnostic spectral             
features. In this data set we include a global cylindrical projection         
plus northern and southern hemisphere stereographic projections of            
of the three color ratios as three bands in the image. The bands are          
created from the quotients of photometrically corrected color images          
where:                                                                        
                                                                              
red   = filter # 3 / filter # 8                                               
green = filter # 3 / filter # 4                                               
blue  = filter # 8 / filter # 3                                               
                                                                              
filter # 3: 749 nm                                                            
filter # 4: 917 nm                                                            
filter # 8: 438 nm                                                            
                                                                              
conversion from real to byte:                                                 
                                                                              
red   : input range 1.106 - 1.337 -> output range 1 - 255                     
green : input range 1.018 - 2.036 -> output range 1 - 255                     
blue  : input range 0.769 - 0.905 -> output range 1 - 255                     
                                                                              
map_scale = 60 m/pixel                                                        
                                                                              
Calibration, stray light correction, and photometric correction               
as described by [SCHROEDERETAL2013A] and [SCHROEDERETAL2014].