Image 06

original 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    : 2005:08:04 14:43:24
# Resolution   : 2048 x 1536 in jpeg (2064x1540 in pgm/06.pgm)
# Focal length :  8.2mm
# Exposure time: 0.004 s  (1/250)
# Aperture     : f/7.0
# ISO equiv.   : 100

#c li count  min   Yav   max  ovf   min  Cav    max   ovf   min  Gav    max   ovf   min  Mav   max   ovf
# %    Y     C     G     M readings  Y        C        G        M        L / cd/m2
  1    -4     0   -12    -8      -3.14     0.00    -11.7    -8.23    -0.578 
 10    34    38    28    28       26.7     31.6     27.3     28.8     26.5  
 50  1040   974   832   778        817      811      810      800      819  
 90 16296 16300 15534 15386       1.28E4   1.36E4   1.51E4   1.58E4   1.21E4
 99 16316 16316 16316 16314       1.28E4   1.36E4   1.59E4   1.68E4   1.19E4
100 16344 16346 16358 16344       1.28E4   1.36E4   1.59E4   1.68E4   1.19E4
# flux from 3.89 sr ( 1.62E-5 sr/4px) is  1.24E4 lx (SQM 4.23E3 nt,  3.52 mag);
# tilewise luminance  3.18E3 cd/m2 with rel. SD  129 % (summing pixels below 16380)
# dark frame dark/off.pgm subtracted from all values
# Yell average=3746.7  minimum=  -62  maximum=16344   over 16380: 60244
# Cyan average=3229.0  minimum=  -50  maximum=16346   over 16380: 55361
# Gree average=4139.6  minimum=  -70  maximum=16358   over 16380: 113770
# Mage average=4181.1  minimum=  -66  maximum=16344   over 16380: 153958

End of results of "raw2lum" (version 1.22) with parameters:
  -c YCGM -fa -w 7.3 -fc0.214 -o 16380 -d dark/off.pgm -sm200 -nh -i 06.txt -e 06.eps -n 06.ppm -t156 -c 3412 -s64 pgm/06.pgm
Luminance scale / 1 cd/m<sup>2</sup>
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)