Image 09


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 00:34:56
# Resolution   : 2048 x 1536 in jpeg (2064x1540 in pgm/09.pgm)
# Focal length : 11.2mm
# Exposure time: 2.000 s 
# Aperture     : f/2.8
# 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   -24   -32   -40   -32      -0.00603  -0.00852  -0.0125  -0.0105  -0.00410
 10     4    -8   -12    -4       0.00101  -0.00213  -0.00374  -0.00132   0.00243
 50    76    36    36    52       0.0191   0.00959   0.0112   0.0171   0.0215
 90   348   132   152   236       0.0874   0.0352   0.0474   0.0777   0.0995
 99  1632   628   708  1112       0.410    0.167    0.221    0.366    0.467 
100 16332 16332 16344 16352       4.10     4.35     5.09     5.38     3.81  
# flux from 5.55 sr ( 8.71E-6 sr/4px) is  0.228 lx (SQM 0.0954 nt, 15.14 mag);
# tilewise luminance  0.0482 cd/m2 with rel. SD  140 % (summing pixels below 16380)
# dark frame dark/2s.pgm subtracted from all values
# Yell average= 174.0  minimum= -116  maximum=16332   over 16380: 284
# Cyan average=  71.7  minimum= -176  maximum=16332   over 16380: 414
# Gree average=  77.9  minimum= -224  maximum=16344   over 16380: 534
# Mage average= 119.5  minimum= -512  maximum=16352   over 16380: 266

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 09.txt -e 09.eps -n 09.ppm -t156 -c 3412 -s64 pgm/09.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)