Image 44


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 03:01:05
# Resolution   : 1280 x 960 in jpeg (1424x1076 in pgm/44.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   -23   -15   -15   -35        -0.00661  -0.00249  -0.00913  -0.00393
 10    28    34    34     2         0.00805   0.00565   5.21E-4   0.00649
 50   208   212   213    79         0.0598   0.0353   0.0206   0.0439
 90  1347  1300  1303   357         0.387    0.216    0.0931   0.276 
 99  6312  5948  5958  2020         1.81     0.989    0.527    1.28  
100 15869 15866 15866 15867         4.56     2.64     4.14     3.31  
# flux from 0.651*0.98 sr ( 8.59E-7 sr/4px) is  0.0710 lx ( 0.0733 lx tilewise);
# tilewise luminance  0.115 cd/m2 with rel. SD  126 % (summing pixels below 15850 and with non-zero green: there is 98.3 % of them)
# Fuji Devignetting: 1 # dark frame dark/43.pgm subtracted from all values
# Red  average= 556.4  minimum= -116  maximum=15869   over 15850: 2971 zero:  1.8 %
# GrUp average= 540.4  minimum= -118  maximum=15866   over 15850: 2972 zero:  1.7 %
# GrDw average= 541.8  minimum= -100  maximum=15866   over 15850: 2944 zero:  1.7 %
# Blue average= 192.5  minimum= -145  maximum=15867   over 15850: 1613 zero:  4.5 %

End of results of "raw2lum" (version 1.22) with parameters:
  -c fuji -fa -d dark/43.pgm -sm100 -nh -nt -i 44.txt -e 44.eps -n 44.ppm -t 118 -s71:76 pgm/44.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)