We introduce a new edge-directed interpolator based on locally defined, straight line approximations of image isophotes. Spatial derivatives of image intensity are used to describe the principal behavior of pixel-intersecting isophotes in terms of their slopes. The slopes are determined by inverting a tridiagonal matrix and are forced to vary linearly from pixel-to-pixel within segments. Image resizing is performed by interpolating along the approximated isophotes. The proposed method can accommodate arbitrary scaling factors, provides state-of-the-art results in terms of PSNR as well as other quantitative visual quality metrics, and has the advantage of reduced computational complexity that is directly proportional to the number of pixels.

Original languageEnglish (US)
Article number6357284
Pages (from-to)2960-2969
Number of pages10
JournalIEEE Transactions on Image Processing
Issue number8
StatePublished - Jun 7 2013


  • Directional interpolation
  • gradient angle
  • image upsampling
  • isophote
  • piecewise linear

ASJC Scopus subject areas

  • Software
  • Computer Graphics and Computer-Aided Design


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