Various images of the Müller–Lyer figures have been obtained by digital filtering. The filtered images contained a definite spatial-frequency spectrum, predominantly low, medium, or high frequencies. The filtering was carried out by convolution of the images with wavelets that are the difference of two Gaussoids with half-width differing by a factor of 2. The equalization threshold of the Müller–Lyer figures was measured by presenting images subjected to digital processing and without processing, thereby measuring the threshold for bringing about the illusion. The Müller–Lyer illusion was caused by all the stimuli, but it was reliably larger in response to the presentation of the image with a predominantly low-frequency component. The modelling of the Müller–Lyer illusion must take into account the spatial-frequency spectrum of the test image and the characteristics of the pass-band filtering in the spatial-frequency channels of not only the primary but also the higher divisions of the visual system, which construct the envelope based on the primary filtering of the image.
© 2011 OSAPDF Article