Image 53

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 03:07:20
# Resolution   : 1280 x 960 in jpeg (1424x1076 in pgm/53.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   -19   -15   -15   -22        -0.00546  -0.00249  -0.00574  -0.00353
 50    24    22    22    12         0.00690   0.00365   0.00313   0.00479
 90   326   265   265    75         0.0937   0.0440   0.0196   0.0614
 99  3324  2502  2501   367         0.955    0.416    0.0957   0.604 
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  0.0207 lx ( 0.0222 lx tilewise);
# tilewise luminance  0.0313 cd/m2 with rel. SD  233 % (summing pixels below 15850 and with non-zero green: there is 76.7 % of them)
# Fuji Devignetting: 1 # dark frame dark/43.pgm subtracted from all values
# Red  average= 215.0  minimum= -269  maximum=15869   over 15850: 623 zero: 19.6 %
# GrUp average= 180.0  minimum= -118  maximum=15866   over 15850: 522 zero: 23.3 %
# GrDw average= 180.0  minimum= -112  maximum=15866   over 15850: 521 zero: 23.4 %
# Blue average=  42.0  minimum= -372  maximum=15867   over 15850: 112 zero: 26.0 %

End of results of "raw2lum" (version 1.22) with parameters:
  -c fuji -fa -d dark/43.pgm -sm100 -nh -nt -i 53.txt -e 53.eps -n 53.ppm -t 118 -s71:76 pgm/53.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)