Contrast enhancement based on layered difference representation of 2D histograms

Chul Lee, Chang-Su Kim, Chulwoo Lee

Research output: Contribution to journalArticlepeer-review

513 Citations (Scopus)


A novel contrast enhancement algorithm based on the layered difference representation of 2D histograms is proposed in this paper. We attempt to enhance image contrast by amplifying the gray-level differences between adjacent pixels. To this end, we obtain the 2D histogram h(k, k + l ) from an input image, which counts the pairs of adjacent pixels with gray-levels k and k + l , and represent the gray-level differences in a tree-like layered structure. Then, we formulate a constrained optimization problem based on the observation that the gray-level differences, occurring more frequently in the input image, should be more emphasized in the output image. We first solve the optimization problem to derive the transformation function at each layer. We then combine the transformation functions at all layers into the unified transformation function, which is used to map input graylevels to output gray-levels. Experimental results demonstrate that the proposed algorithm enhances images efficiently in terms of both objective quality and subjective quality.

Original languageEnglish
Article number6615961
Pages (from-to)5372-5384
Number of pages13
JournalIEEE Transactions on Image Processing
Issue number12
Publication statusPublished - 2013 Dec


  • 2D histogram
  • Constrained optimization
  • Contrast enhancement
  • Histogram equalization
  • Image enhancement
  • Layered difference representation

ASJC Scopus subject areas

  • Software
  • Computer Graphics and Computer-Aided Design


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