A possible explanation of the low-level brightness–contrast illusions in the light of an extended classical receptive field model of retinal ganglion cells

Abstract

The low-level brightness-contrast illusions constitute a special class within visual illusions. Speculations exist that these illusions may be processed through the filtering action of the retinal ganglion cells without necessitating much intervention from higher order processes of visual perception. Concept of the classical receptive field of the ganglion cell, derived from early physiological studies, prompted the idea that a Difference of Gaussian (DoG) model might explain the low-level illusions. In spite of its many successes, the DoG model fails to explain some of these illusions. It has been shown in this paper that it is possible to simulate those illusions with a model that takes into cognizance the role of the extended classical receptive field.

Early Vision and Image Processing: Evidences Favouring a Dynamic Receptive Field Model

“…The modified DoG model proposed in the previous section has been found to be very effective in explaining many brightness-contrast illusions [9]. From this work, we find that the model is actually a dynamic one that operates at practically three different sets of amplitudes (A 1 , A 2 and A 3 ) and sampling intervals depending upon the illusory stimulus.…”

“…From this work, we find that the model is actually a dynamic one that operates at practically three different sets of amplitudes (A 1 , A 2 and A 3 ) and sampling intervals depending upon the illusory stimulus. If we apply the set of values used for explaining SBC by the proposed model [9], then convoluting Figure 7 with this model we achieve an explanation of the perception of those seventeen observers who reported an opposite perception of brightness compared to White effect. This has been shown in Figure 8 (a) and in its horizontal line profiles in Figure 8 (b).…”

“…If on the other hand, we apply the settings for explaining Mach band and Hermann grid illusion [9] when convoluting, we arrive at the explanation of those thirteen observers who reported equiluminance for both the patches. The convolution result and its corresponding line profiles are shown in Figure 9 (a) and 9 (b).…”

“…When the brightness of a test region shifts away from the brightness of the surround region the phenomenon is termed as a brightness-contrast event. Such events, like the Mach band, the Simultaneous Brightness-contrast, the Hermann grid illusion or the grating induction effect can be more or less explained with the help of the isotropic DoG model of primary visual processing [4], even though there are still many subtle aspects of these stimuli that require a deeper understanding of how even these low-level brightness-contrast illusions are actually processed [9,10]. Let us first consider the Simultaneous Brightness-contrast (SBC) illusion shown in Figure 1.…”

Saliency computation via whitened frequency band selection

“…This area is regarded as non-Classical Receptive Field (nCRF) that can inhibit the antagonistic effect of center-surround and compensate the loss of low-frequency components. In order to explain the relation between CRF and nCRF, Ghosh et al (2006) suggested the following equation named ECRF using three zero-mean Gaussians with different variances:…”