Image 33


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 02:53:55
# Resolution   : 1280 x 960 in jpeg (1424x1076 in pgm/33.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   -50   -46   -47   -52        -0.0575  -0.0309  -0.0542  -0.0402
 10   -17   -14   -14   -21        -0.0195  -0.00930  -0.0219  -0.0129
 50    24    26    26    11         0.0276   0.0173   0.0115   0.0209
 90   142   150   150    74         0.163    0.0997   0.0772   0.122 
 99  1264  1349  1325   418         1.45     0.888    0.436    1.09  
100 15961 15958 15958 15959         18.3     10.6     16.6     13.3  
# flux from 0.654*0.79 sr ( 8.59E-7 sr/4px) is  0.0451 lx ( 0.0539 lx tilewise);
# tilewise luminance  0.0786 cd/m2 with rel. SD  155 % (summing pixels below 15850 and with non-zero green: there is 79.4 % of them)
# Fuji Devignetting: 1 # dark frame dark/42.pgm subtracted from all values
# Red  average= 103.4  minimum= -126  maximum=15961   over 15850: 400 zero: 19.8 %
# GrUp average= 111.1  minimum= -129  maximum=15958   over 15850: 359 zero: 20.7 %
# GrDw average= 109.8  minimum= -115  maximum=15958   over 15850: 408 zero: 20.4 %
# Blue average=  47.4  minimum= -114  maximum=15959   over 15850: 178 zero: 28.0 %

End of results of "raw2lum" (version 1.22) with parameters:
  -c fuji -fa -d dark/42.pgm -sm100 -nh -nt -i 33.txt -e 33.eps -n 33.ppm -t 118 -s71:76 pgm/33.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)