A Possible Role and Basis of Visual Pathway Selection in Brightness Induction

Abstract

It is a well-known fact that the perceived brightness of any surface depends on the brightness of the surfaces that surround it. This phenomenon is termed as brightness induction. Isotropic arrays of multi-scale DoG (Difference of Gaussians) as well as cortical Oriented DoG (ODOG) and extensions thereof, like the Frequency-specific Locally Normalized ODOG (FLODOG) functions have been employed towards prediction of the direction of brightness induction in many brightness perception effects. But the neural basis of such spatial filters is seldom obvious. For instance, the visual information from retinal ganglion cells to such spatial filters, which have been generally speculated to appear at the early stage of cortical processing, are fed by at least three parallel channels viz. Parvocellular (P), Magnocellular (M) and Koniocellular (K) in the subcortical pathway, but the role of such pathways in brightness induction is generally not implicit. In this work, three different spatial filters based on an extended classical receptive field (ECRF) model of retinal ganglion cells, have been approximately related to the spatial contrast sensitivity functions of these three parallel channels. Based on our analysis involving different brightness perception effects, we propose that the M channel, with maximum conduction velocity, may have a special role for an initial sensorial perception. As a result, brightness assimilation may be the consequence of vision at a glance through the M pathway; contrast effect may be the consequence of a subsequent vision with scrutiny through the P channel; and the K pathway response may represent an intermediate situation resulting in ambiguity in brightness perception. The present work attempts to correlate this phenomenon of pathway selection with the complementary nature of these channels in terms of spatial frequency as well as contrast.

Experimental Observations of the Visibility Threshold of Illusory effects in Hermann Grid, Sinusoidal and Square Gratings and their Possible Implications

“…This is a fundamental difference between these two illusions, which otherwise superficially may seem to represent similar effects. Hence, these two are likely to have very different origins within the brain, much in the same way as White's illusion differs from the Simultaneous Brightness contrast illusion [16]. In Experiment 3 we observe that both upper and lower thresholds are present in the Hermann grid illusion.…”

Comparison Between an HVS Inspired Linear Filter and the Bilateral Filter in Performing "Vision at a Glance" through Smoothing with Edge Preservation

“…16 The weights assigned to the center, surround and extended surrounds for the M-channel filter are A 1 = 10, A 2 = 0.99, A 3 = 0.08 and sampling interval = 0.5. 1 The M-channel filter in one dimension and its corresponding frequency response have been demonstrated in Figs. 1 and 2, respectively.…”

“…The established and prevalent viewpoint conceives that the human visual system (HVS) perceives categorical information at a glance (using high level cortical mechanisms) and miss (or assume) details that are detected by lower areas but not represented in the individual high-level receptive fields. 1 We perceive the details later by focusing serially on the components and features, slowly scanning them one at a time. 2 The reverse hierarchy theory (RHT) of Ahissar and Hochstein proposes that such an initial "vision at a glance" includes results of automatic and implicit bottom-up processing, which makes the initial explicit perception introspectively direct without conscious antecedents.…”

Development of rapidly solidified 6.5 wt% silicon steel for magnetic applications

“…1. Brightness illusions can be classified into three major classes according to changes in directions of the brightness: 1) brightness-contrast, 2) brightness-assimilation, and 3) illusory blobs or region illusions [1]. In brightness-contrast illusions, the brightness induction in the test patch occurs in opposite direction to the surrounding luminance such as the simultaneous brightness contrast (SBC) [2] in Fig.…”

“…Localizing illusory regions is important as it helps to identify the nature of illusions and facilitate understanding the reason behind the illusory phenomenon [6,7,1]. Localizing illusory regions in a brightness illusion is challenging as the intensity values in the illusory and non-illusory regions can be exactly the same (Fig.…”