Are Edges Incomplete?

  • Authors:
  • James H. Elder

  • Affiliations:
  • Centre for Vision Research, York University, 4700 Keele Street, North York, Ontario, Canada M3J 1P3. jelder@yorku.ca

  • Venue:
  • International Journal of Computer Vision - Special issue on computer vision research at NEC Research Institute
  • Year:
  • 1999

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Abstract

We address the problem of computing a general-purpose early visualrepresentation that satisfies two criteria. 1)Explicitness: To be more useful than the original pixel array, therepresentation must take a significant step toward making important imagestructure explicit. 2) Completeness: To support a diverse set ofhigh-level tasks, the representation must not discard information of potentialperceptual relevance. The most prevalent representation in image processingand computer vision that satisfies the completeness criterion is the waveletcode. In this paper, we propose a very different code which represents thelocation of each edge and the magnitude and blur scale of the underlyingintensity change. By making edge structure explicit, we argue that thisrepresentation better satisfies the first criterion than do wavelet codes. To address the second criterion, we study the question of how much visualinformation is lost in the representation. We report a novel method forinverting the edge code to reconstruct a perceptually accurate estimate of theoriginal image, and thus demonstrate that the proposed representation embodiesvirtually all of the perceptually relevantinformation contained in a natural image. This resultbears on recent claims that edge representations do not contain all of theinformation needed for higher level tasks.