Contrast enhancement of color images based on Wavelet Transform and human visual system

  • Authors:
  • Ding Xiao;Jun Ohya

  • Affiliations:
  • Waseda University, Ohkuboyama, Nishitomita, Honjo-shi, Saitama-ken, Japan;Waseda University, Ohkuboyama, Nishitomita, Honjo-shi, Saitama-ken, Japan

  • Venue:
  • GVE '07 Proceedings of the IASTED International Conference on Graphics and Visualization in Engineering
  • Year:
  • 2007

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Abstract

This paper proposes a new method for enhancing the contrast of color images based on Wavelet Transform and human visual system. The RGB (red, green, and blue) values of each pixel in a color image are converted to HSV (hue, saturation and value) values. To the V (luminance value) components of the color image, Wavelet Transform is applied so that the V components are decomposed into the approximate components and detail components. The obtained coefficients of the approximate components are converted by a grey-level contrast enhancement technique based on human visual system. Then, inverse Wavelet transform is performed for the converted coefficients so that the enhanced V values are obtained. The S components are enhanced by histogram equalization. The H components are not changed, because changes in the H components could degrade the color balance between the HSV components. The enhanced S and V together with H are converted back to RGB values. The effectiveness of the proposed method is demonstrated experimentally.