Abstract
The visibility of a grating patch is altered when it is surrounded by another grating. Here, we determined the visibility of a grating patch when it is surrounded by complex images of varying second-order statistics. The 86 correct detection threshold of a 256 grey-level grating patch (1.00 deg × 0.13 deg, spatial frequency 6 cycles deg-1) was measured when it was surrounded by different complex images (4 deg × 4 deg). The surrounding images were derived from either real natural images, or from random luminance patterns, filtered to different second-order statistics. The detection threshold of the grating in natural images was found to be highest when the surrounding images had the characteristic statistics of real-world scenes. The detection threshold of a grating surrounded by filtered random-luminance patterns was highest when the surrounds were, in comparison to natural scenes, slightly de-correlated. The results show that the detection thresholds of gratings are affected by the statistics of their surrounding stimuli. The thresholds are higher when the surrounding stimuli have the statistics of natural images.
