• Publications
  • Influence
Quest: A Bayesian adaptive psychometric method
An adaptive psychometric procedure that places each trial at the current most probable Bayesian estimate of threshold is described. The procedure takes advantage of the common finding that the humanExpand
Model of human visual-motion sensing.
  • A. Watson, A. Ahumada
  • Computer Science, Medicine
  • Journal of the Optical Society of America. A…
  • 1 February 1985
A model of how humans sense the velocity of moving images, using a set of spatial-frequency-tuned, direction-selective linear sensors, agrees qualitatively with human perception. Expand
DCT quantization matrices visually optimized for individual images
  • A. Watson
  • Mathematics, Engineering
  • Electronic Imaging
  • 8 September 1993
Several image compression standards (JPEG, MPEG, H.261) are based on the Discrete Cosine Transform (DCT). These standards do not specify the actual DCT quantization matrix. Ahumada & Peterson andExpand
Model of visual contrast gain control and pattern masking.
  • A. Watson, J. Solomon
  • Computer Science, Medicine
  • Journal of the Optical Society of America. A…
  • 1 September 1997
We have implemented a model of contrast gain and control in human vision that incorporates a number of key features, including a contrast sensitivity function, multiple oriented bandpass channels,Expand
Visibility of wavelet quantization noise
A mathematical model is constructed for DWT noise detection thresholds that is a function of level, orientation, and display visual resolution that allows calculation of a "perceptually lossless" quantization matrix for which all errors are in theory below the visual threshold. Expand
Probability summation over time
  • A. Watson
  • Medicine, Mathematics
  • Vision Research
  • 31 December 1979
Frequency-of-seeing and sensitivity-duration curves were collected for temporal signals of limited spectral extent and suggest that a stimulus is detected whenever the excursions of its linearly filtered, noise-perturbed temporal waveform exceed some fixed magnitude. Expand
The method treats each DCT coefficient as an approximation to the local response of a visual "channel" and estimates the quantization matrix for a particular image that yields minimum bit rate for a given total perceptual error, or minimum perceptual error for agiven bit rate. Expand
Image Compression Using the Discrete Cosine Transform
Some simple functions to compute the discrete cosine transform and how it is used for image compression are developed to illustrate the use of Mathematica in image processing and to provide the reader with the basic tools for further exploration of this subject. Expand
The cortex transform: rapid computation of simulated neural images
A transform which maps an image into a set of images that vary in resolution and orientation, each pixel in the output may be regarded as the simulated response of a neuron in human visual cortex is described. Expand
Spatio‐temporal interactions in cat retinal ganglion cells showing linear spatial summation.
The spatio‐temporal characteristics of cat retinal ganglion cells showing linear summation have been studied and it has been demonstrated not only that X cells behave approximately linearly when responding with amplitudes of less than about 10 impulses/sec to stimuli of low contrast but also that cells of another type with larger receptive field centres (Q cells) behave Approximately linearly under the same conditions. Expand