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H A Piceni

Publications and source records attributed to H A Piceni.

2 recordsLinked to original sources
PubMed1991

A pseudomatched filter model applied to the transient system of human vision.

A pseudomatched filter configuration is presented as a model for the transient system of the human visual perception. This model has resemblances to the Reichardt [1] and the Rashbass [2] model, but on the other hand the pseudomatched filter model is linear. The choice of the model is based on the shape of the psychophysically measured impulse response and on physiological and functional arguments. The parameters of the model are estimated for different data sets. The behavior of the model agrees with the experimental data in all essential aspects, and can be used for prediction and further modeling of the human visual system.

Confidence Intervals↗
PubMed1980

Instabilities in a continuous medium model for the retina.

The shape of the spatial response of the retina on a small light stimulus as found by Rodieck (1965) for the cat, and proposed for the human retina among others by Korn and von Seelen (1972), resembles a Mexican hat known as a sombrero. A model presented by Röhler (1976), using a continuous medium as a description of the retina, can lead to such a "Mexican hat" response function for a specific choice of parameters. The spatial Fourier transform of this response function has a general appearance that corresponds to that calculated for stationary signals. However, such an analysis of the model for stationary signals is incomplete. Inspection of the time-dependent equations shows that it is unstable precisely for those parameter values that give the stationary response function its desired shape. Such stationary situations cannot be physically realized since the model is unstable.

Animals↗