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Image Noise

The signal-to-noise ratio allows evaluating the tolerance of the scanner’s electronics to various kinds of noise. Noise can be random or correlated, so we have two test steps here.

Random Noise

The graphs below show the dependence of the amount of random noise on the reflecting capability of the areas of the Kodak IT8.7/2 Q-60R2 target.


The graph shows the dependence of the random noise value
on the reflective capacity of the original

The signal-to-noise ratio is the ratio of the median to the deviation on an area of the target. Bigger SNR values are better, indicating the scanner’s higher tolerance to noise. The delta SNR parameter is the sum of the measurements.

Correlated noise

Correlated noise shows up in images as regular patterns. Prevalence of such noise greatly reduces the SNR coefficient, which is found as the ratio of the median to deviation. The calculated coefficients are listed in the following diagram (bigger values are better):

 
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