Image 07


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    : 2005:08:05 00:34:01
# Resolution   : 2048 x 1536 in jpeg (2064x1540 in pgm/07.pgm)
# Focal length : 11.2mm
# Exposure time: 2.000 s 
# Aperture     : f/7.8
# 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   -36   -40   -52   -44      -0.0702  -0.0827  -0.126   -0.112   -0.0535
 10   -12   -20   -24   -20      -0.0234  -0.0413  -0.0580  -0.0511  -0.0130
 50    16     8     8    12       0.0312   0.0165   0.0193   0.0307   0.0348
 90    60    36    44    48       0.117    0.0744   0.106    0.123    0.120 
 99   280   112   128   188       0.546    0.232    0.310    0.480    0.617 
100 16332 16332 16340 16352       31.8     33.8     39.5     41.8     29.5  
# flux from 5.55 sr ( 8.71E-6 sr/4px) is  0.317 lx (SQM 0.131 nt, 14.79 mag);
# tilewise luminance  0.0673 cd/m2 with rel. SD  210 % (summing pixels below 16380)
# dark frame dark/2s.pgm subtracted from all values
# Yell average=  31.1  minimum= -132  maximum=16332   over 16380: 115
# Cyan average=  13.1  minimum= -352  maximum=16332   over 16380: 139
# Gree average=  12.8  minimum= -284  maximum=16340   over 16380: 174
# Mage average=  20.5  minimum= -512  maximum=16352   over 16380: 119

End of results of "raw2lum" (version 1.22) with parameters:
  -c YCGM -fa -w 7.3 -fc0.214 -o 16380 -d dark/2s.pgm -sm200 -nh -i 07.txt -e 07.eps -n 07.ppm -t156 -c 3412 -s64 pgm/07.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)