Image 14


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 02:36:55
# Resolution   : 1280 x 960 in jpeg (1424x1076 in pgm/14.pgm)
# Focal length : 17.2mm  (35mm equivalent: 116mm)
# CCD width    : 5.32mm
# Exposure time: 2.000 s 
# Aperture     : f/3.2
# ISO equiv.   : 200

# Selected image percentils         L=(1.730*0.35*R+1.000*0.65*G+1.570*0.00*B)* 2.17E-4
# %    R     G1    G2    B readings  R        G        B        L / cd/m2
  1   -58   -53   -53   -58        -0.0218  -0.0115  -0.0198  -0.0151
 10   -28   -24   -24   -27        -0.0105  -0.00521  -0.00920  -0.00706
 50     2     0     0     0         7.51E-4   0.00     0.00     2.63E-4
 90    53    48    49    46         0.0199   0.0105   0.0157   0.0138
 99  1071   834   835   131         0.402    0.181    0.0446   0.258 
100 15869 15866 15866 15867         5.96     3.44     5.40     4.32  
# flux from 0.0722*0.60 sr ( 9.44E-8 sr/4px) is  6.48E-4 lx ( 8.39E-4 lx tilewise);
# tilewise luminance  0.0105 cd/m2 with rel. SD  325 % (summing pixels below 15850 and with non-zero green: there is 59.8 % of them)
# Fuji Devignetting: 2 # dark frame dark/43.pgm subtracted from all values
# Red  average=  54.9  minimum= -288  maximum=15869   over 15850: 143 zero: 33.2 %
# GrUp average=  51.5  minimum= -119  maximum=15866   over 15850: 110 zero: 40.7 %
# GrDw average=  50.9  minimum= -119  maximum=15866   over 15850: 112 zero: 39.7 %
# Blue average=  16.5  minimum= -366  maximum=15867   over 15850:   4 zero: 37.3 %

End of results of "raw2lum" (version 1.22) with parameters:
  -c fuji -fa -d dark/43.pgm -sm100 -nh -nt -i 14.txt -e 14.eps -n 14.ppm -t 118 -s71:76 pgm/14.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)