Image 48


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 03:03:35
# Resolution   : 1280 x 960 in jpeg (1424x1076 in pgm/48.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   -44   -39   -39   -45        -0.0506  -0.0259  -0.0469  -0.0345
 10    -7    -2    -2   -12        -0.00805  -0.00133  -0.0125  -0.00368
 50    70    81    80    35         0.0805   0.0535   0.0365   0.0629
 90   659   721   721   223         0.757    0.479    0.233    0.576 
 99  1259  1320  1321   453         1.45     0.877    0.473    1.08  
100 16116 16113 16113 16107         18.5     10.7     16.8     13.4  
# flux from 0.654*0.88 sr ( 8.59E-7 sr/4px) is  0.112 lx ( 0.119 lx tilewise);
# tilewise luminance  0.241 cd/m2 with rel. SD  118 % (summing pixels below 15850 and with non-zero green: there is 87.6 % of them)
# Fuji Devignetting: 1 # dark frame dark/42.pgm subtracted from all values
# Red  average= 231.6  minimum= -143  maximum=16116   over 15850: 327 zero: 12.3 %
# GrUp average= 254.9  minimum= -124  maximum=16113   over 15850: 344 zero: 12.7 %
# GrDw average= 253.4  minimum= -107  maximum=16113   over 15850: 342 zero: 12.2 %
# Blue average=  88.0  minimum= -119  maximum=16107   over 15850: 215 zero: 16.8 %

End of results of "raw2lum" (version 1.22) with parameters:
  -c fuji -fa -d dark/42.pgm -sm100 -nh -nt -i 48.txt -e 48.eps -n 48.ppm -t 118 -s71:76 pgm/48.pgm

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)