ON THE INTRINSIC 2-DIMENSIONALITY OF THE CSF AND ITS MEASUREMENT

Classically the visual system sensitivity has been studied separately as a function of spatial frequency and orientation, without explicitly pointing out the relation between both parameters. As the visual syst em processes two-dimensional signals, its Contrast Sensitivity Functio n (CSF) is intrinsically two-dimensional too, and therefore, the depen dence of the 1-D CSF on orientation is obtained by considering differe nt radial profiles of the 2-D CSF. In the present work, we study the s implest and most straightforward method to obtain the maximum amount o f information about the 2-D CSF with a minimum of measurements. It fol lows from the results that, for emmetropic observers, it is enough to measure two perpendicular radial profiles of the CSF to obtain enough information about the whole 2-D frequency domain, where as for the mos t common astigmatism cases, it's necessary to include another intermed iate measure.Assuming that the Modulation Transfer Function (MTF) is p roportional to the CSF, it's possible to compute the visual system Poi nt Spread Function (PSF), optical and neural parts, from the function experimentally obtained. To estimate the accuracy of the method, the 2 -D PSF is calculated and, we simulate, by computer, the perception of a test using the 2-D CSF measured for emmetropic and astigmatic observ ers.