John Robson

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John is an eminent vision scientist. His many contributions include psychophysical measurement of the human contrast sensitivity function, neurophysiological investigations into spatial frequency selectivity, and pioneering analytical methods that provide seminal insights into the nature of visual processing. The importance of John's work has been recognised by the Friedenwald award of the Association for Research in Vision and Ophthalmology, and the Tillyer award of the Optical Society of America. John was elected a Fellow of the Royal Society in 2003.

Craik Club 2008: Application of Fourier Analysis to the Visibility of Gratings

  1. The contrast thresholds of a variety of grating patterns have been measured over a wide range of spatial frequencies
  2. Contrast thresholds for the detection of gratings whose luminance profiles are sine, square, rectangular or saw-tooth waves can be simply related using Fourier theory
  3. Over a wide range of spatial frequencies the contrast threshold of a grating is determined only by the amplitude of the fundamental Fourier component of its wave form
  4. Gratings of complex wave form cannot be distinguished from sine-wave gratings until their contrast has been raised to a level at which the higher harmonic components reach their independent threshold
  5. These findings can be explained by the existence within the nervous system of linearly operating independent mechanisms selectively sensitive to limited ranges of spatial frequencies.

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