Automatic Contrast Enhancement by Transfer Function Modification

  • Bae, Tae Wuk (IT Convergence Research Laboratory, ETRI) ;
  • Ahn, Sang Ho (Department of Electronic Engineering, Inje University) ;
  • Altunbasak, Yucel (School of Electrical and Computer Engineering, Georgia Institute of Technology)
  • Received : 2015.10.02
  • Accepted : 2016.11.03
  • Published : 2017.02.01


In this study, we propose an automatic contrast enhancement method based on transfer function modification (TFM) by histogram equalization. Previous histogram-based global contrast enhancement techniques employ histogram modification, whereas we propose a direct TFM technique that considers the mean brightness of an image during contrast enhancement. The mean point shifting method using a transfer function is proposed to preserve the mean brightness of an image. In addition, the linearization of transfer function technique, which has a histogram flattening effect, is designed to reduce visual artifacts. An attenuation factor is automatically determined using the maximum value of the probability density function in an image to control its rate of contrast. A new quantitative measurement method called sparsity of a histogram is proposed to obtain a better objective comparison relative to previous global contrast enhancement methods. According to our experimental results, we demonstrated the performance of our proposed method based on generalized measures and the newly proposed measurement.


Grant : Local-based medical device/robot development & medical IT convergence for small and medium enterprise revitalization project

Supported by : ETRI


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