Image 49


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 03:03:42
# Resolution   : 1280 x 960 in jpeg (1424x1076 in pgm/49.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   -46   -42   -43   -47        -0.0529  -0.0282  -0.0490  -0.0369
 10   -12    -8    -8   -14        -0.0138  -0.00532  -0.0146  -0.00828
 50    46    49    49    32         0.0529   0.0326   0.0334   0.0397
 90  1035  1160  1160   398         1.19     0.771    0.415    0.917 
 99  1683  1884  1884   667         1.93     1.25     0.696    1.49  
100 16031 16028 16028 16029         18.4     10.6     16.7     13.4  
# flux from 0.654*0.83 sr ( 8.59E-7 sr/4px) is  0.156 lx ( 0.162 lx tilewise);
# tilewise luminance  0.304 cd/m2 with rel. SD  139 % (summing pixels below 15850 and with non-zero green: there is 83.4 % of them)
# Fuji Devignetting: 1 # dark frame dark/42.pgm subtracted from all values
# Red  average= 332.1  minimum= -113  maximum=16031   over 15850: 172 zero: 16.3 %
# GrUp average= 376.9  minimum= -129  maximum=16028   over 15850: 179 zero: 16.9 %
# GrDw average= 375.3  minimum= -104  maximum=16028   over 15850: 181 zero: 16.4 %
# Blue average= 137.0  minimum= -112  maximum=16029   over 15850: 145 zero: 19.6 %

End of results of "raw2lum" (version 1.22) with parameters:
  -c fuji -fa -d dark/42.pgm -sm100 -nh -nt -i 49.txt -e 49.eps -n 49.ppm -t 118 -s71:76 pgm/49.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)