Visual receptive fields based on photosensitive protein for detecting orientation illusions

We present a biomimetic optical vision system using the photosensitive protein bacteriorhodopsin (bR) to implement all-optical DoG and Gabor filters for detecting the Café Wall illusion. These filters mimic the receptive fields of retinal and cortical neurons and operate without electronic components. DoG filtering revealed contrast polarity through grating induction and edge effects, while Gabor filtering produced twisted cords consistent with the Fraser illusion theory. Our findings demonstrate that retinal and V1-level mechanisms contribute to orientation illusions in distinct ways. This is the first successful hardware-only demonstration of an optical illusion using protein-based materials, highlighting the potential of BR for low-power, miniaturised, and biologically inspired visual information processing systems.