Image 52


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 03:07:13
# Resolution   : 1280 x 960 in jpeg (1424x1076 in pgm/52.pgm)
# Focal length :  5.7mm  (35mm equivalent: 39mm)
# CCD width    : 5.32mm
# Exposure time: 2.000 s 
# 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)* 1.66E-4
# %    R     G1    G2    B readings  R        G        B        L / cd/m2
  1   -52   -47   -47   -53        -0.0149  -0.00781  -0.0138  -0.0103
 10   -18   -15   -15   -22        -0.00517  -0.00249  -0.00574  -0.00343
 50    25    22    22    12         0.00718   0.00365   0.00313   0.00489
 90   339   275   274    76         0.0974   0.0456   0.0198   0.0637
 99  3291  2478  2469   364         0.946    0.411    0.0949   0.598 
100 15869 15866 15866 15867         4.56     2.64     4.14     3.31  
# flux from 0.654*0.77 sr ( 8.59E-7 sr/4px) is  0.0209 lx ( 0.0224 lx tilewise);
# tilewise luminance  0.0315 cd/m2 with rel. SD  238 % (summing pixels below 15850 and with non-zero green: there is 77.1 % of them)
# Fuji Devignetting: 1 # dark frame dark/43.pgm subtracted from all values
# Red  average= 216.2  minimum= -305  maximum=15869   over 15850: 672 zero: 19.3 %
# GrUp average= 181.0  minimum= -118  maximum=15866   over 15850: 560 zero: 22.9 %
# GrDw average= 181.1  minimum= -109  maximum=15866   over 15850: 558 zero: 22.9 %
# Blue average=  42.8  minimum= -347  maximum=15867   over 15850: 107 zero: 25.7 %

End of results of "raw2lum" (version 1.22) with parameters:
  -c fuji -fa -d dark/43.pgm -sm100 -nh -nt -i 52.txt -e 52.eps -n 52.ppm -t 118 -s71:76 pgm/52.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)