Big Ben's Panorama Tutorials

Dynamic Range

Evaluating Results

The images I have included here covered the maximum detectable range of variation.  A visual inspection of the negatives showed very small variations for another 4 EV however by this stage, the variations were so small and noise/film grain so great that any real detail would have been completely useless.  The images below show an enlargement of the relevant edge of the grey rectangle from the lowest and highest exposures recorded

Grey -> White, EV 21    Black -> Grey, EV 1
Image

Noise largely a result of
film grain

 

Image

Noise is a result of:

  • Noise from scanner

  • Texture of paper

  • Film Grain

Normalised Data

Since all of the images displayed a variation in density corresponding to a change in exposure, I could claim that the film has a dynamic range of 20EV  The compression in the highlight detail however make it impractical to get usable image information out of the entire range.  Before evaluating the raw data I'll normalise it to cover the full range of pixel values (0-255)

Relative EV 1 2 3 4 5 6 7 8 9 10 11
Black 0.00 0.37 1.06 3.69 12.68 35.76 77.16 118.72 154.56 185.25 208.84
Grey 0.63 2.51 7.72 24.09 59.33 102.54 140.49 173.03 198.42 220.88 234.69
White 6.99 20.22 44.07 83.05 124.82 161.81 189.67 213.24 230.30 240.64 246.39

 
Relative EV 12 13 14 15 16 17 18 19 20 21
Black 226.77 237.78 244.31 248.21 250.64 251.86 252.68 253.49 254.02 254.27
Grey 242.67 247.26 250.38 252.00 252.87 253.27 253.85 254.34 254.66 254.88
White 249.98 251.96 253.06 253.68 254.10 254.30 254.60 254.82 254.91 255.00

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Dynamic Range Calculations

Subsequent increase in exposure results in >1 increase in pixel value

Criterion: The image displays a change in pixel value of at least 1 for a subsequent increase/decrease in exposure.

Dynamic Range = 16 Stops

Relative EV 1 2 3 4 5 6 7 8 9 10 11
Grey - Black 0.63 2.14 6.67 20.40 46.65 66.78 63.32 54.31 43.87 35.62 25.85
White - Grey 6.36 17.71 36.34 58.96 65.49 59.27 49.19 40.21 31.88 19.76 11.70

 
Relative EV 12 13 14 15 16 17 18 19 20 21
Grey - Black 15.91 9.48 6.07 3.79 2.23 1.41 1.18 0.86 0.64 0.61
White - Grey 7.31 4.70 2.68 1.68 1.22 1.02 0.75 0.47 0.24 0.12

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1EV increase in exposure results in >1 increase in pixel value

Criterion:  1EV change in exposure results in an increase in pixel value of at least 1.

Dynamic Range = 14 stops

Relative E.V 1 2 3 4 5 6 7 8 9 10 11
Mean PV 0.63 2.51 7.72 24.09 59.33 102.54 140.49 173.03 198.42 220.88 234.69
EV(n) - EV(n-1) - 1.88 5.22 16.37 35.24 43.21 37.95 32.55 25.39 22.45 13.81
Relative E.V 12 13 14 15 16 17 18 19 20 21
Mean PV 242.67 247.26 250.38 252.00 252.87 253.27 253.85 254.34 254.66 254.88
EV(n) - EV(n-1) 7.98 4.59 3.12 1.62 0.87 0.40 0.58 0.49 0.32 0.21

Given the extremely broad "shoulder" of the characteristic curve for this film it is difficult to pinpoint an exact figure for the dynamic range.  For the sake of argument I will take the average of the two values calculated above, i.e. 15EV

 

 


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This page, its contents and style, are the responsibility of the author and do not represent the views, policies or opinions of The University of Melbourne. All photographs Ben Kreunen 2000

Ben Kreunen <bernardk@unimelb.edu.au>
Department of Pathology
Last modified: February 24, 2003