Signal detection in power-law noise: effect of spectrum exponents.
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.
Burgess
Arthur E
AE
Brigham and Women's Hospital, Harvard Medical School, 75 Francis St., Boston, Massachusetts 02115, USA. ab2boston@gmail.com
Judy
Philip F
PF
D016477:Artifacts; D003662:Decision Theory; D004056:Differential Threshold; D006801:Humans; D016014:Linear Models; D008327:Mammography / Q000706:statistics & numerical data; D015588:Observer Variation; D012016:Reference Values; D017603:Signal Detection, Psychological; D013269:Stochastic Processes; D013382:Subtraction Technique; D013647:Task Performance and Analysis; D014796:Visual Perception