Image 47

original lighter colour coded

and with an inserted data grid:

(in the middle of tiles, median of raw G-pixels values is given, the bottom value is the tile luminance divided by one candela per square meter). 
# Date/Time    : 2006:06:29 03:02:37
# Resolution   : 1280 x 960 in jpeg (1424x1076 in pgm/47.pgm)
# Focal length :  5.7mm  (35mm equivalent: 39mm)
# CCD width    : 5.32mm
# Exposure time: 0.500 s  (1/2)
# Aperture     : f/2.8
# ISO equiv.   : 200

# Selected image percentils         L=(1.730*0.35*R+1.000*0.65*G+1.570*0.00*B)* 6.64E-4
# %    R     G1    G2    B readings  R        G        B        L / cd/m2
  1   -47   -43   -44   -48        -0.0540  -0.0289  -0.0501  -0.0377
 10   -13   -10   -11   -16        -0.0149  -0.00698  -0.0167  -0.00976
 50    42    43    44    25         0.0483   0.0289   0.0261   0.0357
 90   570   573   573   180         0.655    0.381    0.188    0.477 
 99  1336  1389  1389   462         1.54     0.923    0.482    1.14  
100 15930 15920 15920 15921         18.3     10.6     16.6     13.3  
# flux from 0.654*0.80 sr ( 8.59E-7 sr/4px) is  0.0908 lx ( 0.0973 lx tilewise);
# tilewise luminance  0.177 cd/m2 with rel. SD  138 % (summing pixels below 15850 and with non-zero green: there is 80.5 % of them)
# Fuji Devignetting: 1 # dark frame dark/42.pgm subtracted from all values
# Red  average= 206.8  minimum= -143  maximum=15930   over 15850:  82 zero: 18.0 %
# GrUp average= 217.6  minimum= -105  maximum=15920   over 15850:  98 zero: 19.7 %
# GrDw average= 217.1  minimum= -111  maximum=15920   over 15850: 100 zero: 19.4 %
# Blue average=  77.0  minimum= -120  maximum=15921   over 15850:  44 zero: 22.5 %

End of results of "raw2lum" (version 1.22) with parameters:
  -c fuji -fa -d dark/42.pgm -sm100 -nh -nt -i 47.txt -e 47.eps -n 47.ppm -t 118 -s71:76 pgm/47.pgm
Luminance scale / 1 cd/m<sup>2</sup>
Logarithmic luminance scale (the unit is candela per square meter) – intensities of snow illuminance in lux would be obtained by multiplying the numeric value of luminance by 3.6. For asphalt, such a coefficient is between 20 and 40 (or much less, for specular reflection of distant lamps)