AI Article Synopsis
- Many natural backgrounds have power spectra described by a power-law equation, with the exponent beta ranging from 1.5 to 3.5 for various signals.
- The ideal observer model predicts a linear relationship in a contrast-detail (CD) diagram that shows how contrast thresholds relate to signal size, specifically with a slope determined by the formula m=(beta-2)/2.
- Experimental results from two-alternative forced-choice (2AFC) detection experiments align well with the model's predictions, indicating a consistent detection threshold across varying exponent values.
Article Abstract
Many natural backgrounds have approximately isotropic power spectra of the power-law form, P(f)=K/f(beta), where f is radial frequency. For natural scenes and mammograms, the values of the exponent, beta, range from 1.5 to 3.5. The ideal observer model predicts that for signals with certain properties and backgrounds that can be treated as random noise, a plot of log (contrast threshold) versus log (signal size) will be linear with slope, m, given by: m=(beta-2)/2. This plot is referred to as a contrast-detail (CD) diagram. It is interesting that this predicts a detection threshold that is independent of signal size for beta equal to 2. We present two-alternative forced-choice (2AFC) detection results for human and channelized model observers of a simple signal in filtered noise with exponents from 1.5 to 3.5. The CD diagram results are in good agreement with the prediction of this equation.
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| http://dx.doi.org/10.1364/josaa.24.000b52 | DOI Listing |
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