Image 45


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 03:01:13
# Resolution   : 1280 x 960 in jpeg (1424x1076 in pgm/45.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   -44   -39   -40   -48        -0.0506  -0.0262  -0.0501  -0.0348
 10    -7    -3    -4   -15        -0.00805  -0.00233  -0.0156  -0.00433
 50    53    56    56    24         0.0609   0.0372   0.0250   0.0455
 90   334   329   329   107         0.384    0.219    0.112    0.276 
 99  1589  1507  1504   512         1.83     1.00     0.534    1.29  
100 15961 15958 15958 15959         18.3     10.6     16.6     13.3  
# flux from 0.653*0.88 sr ( 8.59E-7 sr/4px) is  0.0772 lx ( 0.0853 lx tilewise);
# tilewise luminance  0.132 cd/m2 with rel. SD  147 % (summing pixels below 15850 and with non-zero green: there is 88.0 % of them)
# Fuji Devignetting: 1 # dark frame dark/42.pgm subtracted from all values
# Red  average= 166.6  minimum= -127  maximum=15961   over 15850: 1415 zero: 11.6 %
# GrUp average= 165.2  minimum= -129  maximum=15958   over 15850: 1424 zero: 12.1 %
# GrDw average= 165.5  minimum= -109  maximum=15958   over 15850: 1415 zero: 12.0 %
# Blue average=  64.8  minimum= -114  maximum=15959   over 15850: 1200 zero: 19.5 %

End of results of "raw2lum" (version 1.22) with parameters:
  -c fuji -fa -d dark/42.pgm -sm100 -nh -nt -i 45.txt -e 45.eps -n 45.ppm -t 118 -s71:76 pgm/45.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)