Image 32


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 02:52:10
# Resolution   : 1280 x 960 in jpeg (1424x1076 in pgm/32.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   -45   -45   -51        -0.0540  -0.0299  -0.0532  -0.0383
 10   -14   -12   -12   -21        -0.0161  -0.00797  -0.0219  -0.0108
 50    42    37    37    10         0.0483   0.0246   0.0104   0.0329
 90   372   286   286    67         0.428    0.190    0.0699   0.273 
 99   843   634   636   127         0.969    0.422    0.132    0.613 
100 15869 15866 15866 15867         18.2     10.5     16.6     13.2  
# flux from 0.654*0.78 sr ( 8.59E-7 sr/4px) is  0.0583 lx ( 0.0644 lx tilewise);
# tilewise luminance  0.115 cd/m2 with rel. SD  110 % (summing pixels below 15850 and with non-zero green: there is 78.0 % of them)
# Fuji Devignetting: 1 # dark frame dark/42.pgm subtracted from all values
# Red  average= 154.8  minimum= -113  maximum=15869   over 15850: 122 zero: 19.5 %
# GrUp average= 125.8  minimum= -121  maximum=15866   over 15850:  99 zero: 22.5 %
# GrDw average= 124.0  minimum= -115  maximum=15866   over 15850: 100 zero: 21.6 %
# Blue average=  27.3  minimum= -140  maximum=15867   over 15850:  25 zero: 29.0 %

End of results of "raw2lum" (version 1.22) with parameters:
  -c fuji -fa -d dark/42.pgm -sm100 -nh -nt -i 32.txt -e 32.eps -n 32.ppm -t 118 -s71:76 pgm/32.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)