Pattern masking investigations of the second-order visual mechanisms

Pi Chun Huang, Chien Chung Chen

Research output: Contribution to journalConference articlepeer-review

1 Citation (Scopus)


Human visual system is sensitive to both the first-order and the second-order variations in an image. The latter one is especially important for the digital image processing as it allows human observers to perceive the envelope of the pixel intensities as smooth surface instead of the discrete pixels. Here we used pattern masking paradigm to measure the detection threshold of contrast modulated (CM) stimuli, which comprise the modulation of the contrast of horizontal gratings by a vertical Gabor function, under different modulation depth of the CM stimuli. The threshold function showed a typical dipper shape: the threshold decreased with modulation depth (facilitation) at low pedestal depth modulations and then increased (suppression) at high pedestal modulation. The data was well explained by a modified divisive inhibition model that operated both on depth modulation and carrier contrast in the input images. Hence the divisive inhibition, determined by both the first- and the second-order information in the stimuli, is necessary to explain the discrimination between two second-order stimuli.

Original languageEnglish
Article number724016
JournalProceedings of SPIE - The International Society for Optical Engineering
Publication statusPublished - 2009
EventHuman Vision and Electronic Imaging XIV - San Jose, CA, United States
Duration: 2009 Jan 192009 Jan 22

All Science Journal Classification (ASJC) codes

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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