Image 03

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 14:42:41
# Resolution   : 2048 x 1536 in jpeg (2064x1540 in pgm/03.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   -10    -8      -3.14     0.00    -9.74    -8.23    -1.16  
 10    34    38    28    28       26.7     31.6     27.3     28.8     26.5  
 50  1010   942   804   760        793      784      783      782      796  
 90 16298 16300 15688 15538       1.28E4   1.36E4   1.53E4   1.60E4   1.21E4
 99 16316 16316 16318 16316       1.28E4   1.36E4   1.59E4   1.68E4   1.19E4
100 16344 16354 16360 16358       1.28E4   1.36E4   1.59E4   1.68E4   1.19E4
# flux from 3.87 sr ( 1.62E-5 sr/4px) is  1.16E4 lx (SQM 3.78E3 nt,  3.64 mag);
# tilewise luminance  3.16E3 cd/m2 with rel. SD  130 % (summing pixels below 16380)
# dark frame dark/off.pgm subtracted from all values
# Yell average=3536.4  minimum=  -70  maximum=16344   over 16380: 63818
# Cyan average=3058.7  minimum=  -54  maximum=16354   over 16380: 59391
# Gree average=3988.6  minimum=  -68  maximum=16360   over 16380: 118555
# Mage average=4025.4  minimum=  -66  maximum=16358   over 16380: 154758

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 03.txt -e 03.eps -n 03.ppm -t156 -c 3412 -s64 pgm/03.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)