Image 43


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 01:22:39
# Resolution   : 2048 x 1536 in jpeg (2064x1540 in pgm/43.pgm)
# Focal length :  8.2mm
# Exposure time: 0.001 s  (1/1000)
# Aperture     : f/2.5
# 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   -38   -38   -46   -42      -14.1    -15.0    -21.2    -20.5    -12.0  
 10   -20   -20   -26   -22      -7.44    -7.89    -12.0    -10.7    -6.07  
 50     0     0     0     0       0.00     0.00     0.00     0.00     0.00  
 90    20    20    24    22       7.44     7.89     11.1     10.7     6.35  
 99    38    38    46    40       14.1     15.0     21.2     19.5     12.0  
100  1614   466   316   610        600      184      146      297      737  
# flux from 0.528 sr ( 7.01E-7 sr/4px) is  0.0411 lx;
# tilewise luminance  0.102 cd/m2 with rel. SD  522 % (summing pixels below 16380)
# dark frame dark/off.pgm subtracted from all values
# Yell average=   0.1  minimum=  -88  maximum= 1614   over 16380:   0
# Cyan average=  -0.3  minimum=  -80  maximum=  466   over 16380:   0
# Gree average=  -0.2  minimum= -100  maximum=  316   over 16380:   0
# Mage average=  -0.4  minimum=  -80  maximum=  610   over 16380:   0

End of results of "raw2lum" (version 1.22) with parameters:
  -c YCGM -fa -w 7.3 -fc1.03 -o 16380 -d dark/off.pgm -sm200 -nh -i 43.txt -e 43.eps -n 43.ppm -t168 -c 3412 -s64 pgm/43.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)