Image 46


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 03:01:48
# Resolution   : 1280 x 960 in jpeg (1424x1076 in pgm/46.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   -41   -41   -48        -0.0506  -0.0272  -0.0501  -0.0354
 10    -8    -6    -6   -16        -0.00920  -0.00399  -0.0167  -0.00581
 50    48    48    49    20         0.0552   0.0322   0.0209   0.0403
 90   446   402   402   113         0.513    0.267    0.118    0.353 
 99  2219  2172  2177   704         2.55     1.44     0.734    1.83  
100 16383 16383 16383 16383         18.8     10.9     17.1     13.7  
# flux from 0.653*0.85 sr ( 8.59E-7 sr/4px) is  0.0912 lx ( 0.101 lx tilewise);
# tilewise luminance  0.150 cd/m2 with rel. SD  163 % (summing pixels below 15850 and with non-zero green: there is 85.2 % of them)
# Fuji Devignetting: 1 # dark frame dark/42.pgm subtracted from all values
# Red  average= 208.3  minimum= -113  maximum=16383   over 15850: 1193 zero: 13.8 %
# GrUp average= 201.8  minimum= -108  maximum=16383   over 15850: 1237 zero: 14.9 %
# GrDw average= 202.0  minimum= -107  maximum=16383   over 15850: 1220 zero: 14.7 %
# Blue average=  85.0  minimum= -110  maximum=16383   over 15850: 306 zero: 22.5 %

End of results of "raw2lum" (version 1.22) with parameters:
  -c fuji -fa -d dark/42.pgm -sm100 -nh -nt -i 46.txt -e 46.eps -n 46.ppm -t 118 -s71:76 pgm/46.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)