Image 10


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 00:35:17
# Resolution   : 2048 x 1536 in jpeg (2064x1540 in pgm/10.pgm)
# Focal length : 11.2mm
# Exposure time: 0.125 s  (1/8)
# 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
# Image percentils         L=(1.000*1.30*Y+1.060*0.00*C+1.240*-0.30*G+1.310*0.00*M)* 0.00402
# %    Y     C     G     M readings  Y        C        G        M        L / cd/m2
  1   -34   -36   -44   -38      -0.14    -0.15    -0.22    -0.20    -0.11  
 10   -16   -18   -22   -18      -0.064   -0.077   -0.11    -0.095   -0.051 
 50     8     2     4     6       0.032    0.0085   0.020    0.032    0.036 
 90    36    26    32    32       0.14     0.11     0.16     0.17     0.14  
 99   108    54    62    78       0.43     0.23     0.31     0.41     0.47  
100 16322 16324 16334 16324        66       70       81       86       61   
# flux from 5.55 sr ( 8.71E-6 sr/4px) is  0.260  (summing all pixels below 16380)
# dark frame dark/off.pgm has been subtracted from all values
# Yell average=  12.8  minimum=  -84  maximum=16322   over 16380:  72
# Cyan average=   5.0  minimum=  -84  maximum=16324   over 16380:  76
# Gree average=   5.7  minimum= -106  maximum=16334   over 16380:  90
# Mage average=   8.8  minimum=  -94  maximum=16324   over 16380:  66

End of results of "raw2lum" (version 1.07) with parameters:
  -c YCGM -fa -w 7.3 -fc0.214 -o 16380 -d dark/off.pgm -sm200 -i 10.txt -e 10.eps -n 10.ppm -t156 -c 3412 -s32 pgm/10.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)