Perception
29(9) 1087
In the abstract of the paper “Discrimination of spectrally blended natural images:
Optimisation of the human visual system for encoding natural images” by David J Tolhurst
and Yoav Tadmor the last line has been omitted. The complete abstract is printed
below:
Abstract. We have developed a protocol for testing
experimentally the hypothesis that the human visual system is optimised
for making visual discriminations amongst natural scenes.Visual stimuli
were made by gradual blending of the Fourier spectra of digitised photographs of natural
scenes. The statistics of the stimuli were made unnatural to varying degrees by changing
the overall slopes of the amplitude spectra of the stimuli. Thresholds were measured for
discriminating small amounts of spectral blending at different spectral slopes. We found
that thresholds were lowest when the spectral slope was natural; thresholds were increased
when the slopes were either shallower or steeper than natural. A number of spurious cues
were considered, such as differences in mean luminance or overall spectral power or
contrast between test and reference stimuli. Control experiments were performed to remove
such spurious cues, and the discrimination thresholds were still lowest for stimuli that
were most natural. Thus, these experiments do provide experimental support for the idea
that human vision and the human visual system are optimised for processing natural visual
information.
