Fast and robust wavelet-based dynamic range compression with local contrast enhancement

Numan Unaldi; Vijayan K. Asari; Zia-ur Rahman

doi:10.1117/12.778025

24 April 2008 Fast and robust wavelet-based dynamic range compression with local contrast enhancement

Numan Unaldi, Vijayan K. Asari, Zia-ur Rahman

Proceedings Volume 6978, Visual Information Processing XVII; 697805 (2008) https://doi.org/10.1117/12.778025
Event: SPIE Defense and Security Symposium, 2008, Orlando, Florida, United States

Abstract

In this paper, a new wavelet-based dynamic range compression algorithm is proposed to improve the visual quality of digital images captured in the high dynamic range scenes with non-uniform lighting conditions. Wavelet transform is used especially for dimension reduction such that a dynamic range compression with local contrast enhancement algorithm is applied only to the approximation coefficients which are obtained by low-pass filtering and down-sampling the original intensity image. The normalized approximation coefficients are transformed using a hyperbolic sine curve and the contrast enhancement is realized by tuning the magnitude of the each coefficient with respect to surrounding coefficients. The transformed coefficients are then de-normalized to their original range. The detail coefficients are also modified to prevent the edge deformation. The inverse wavelet transform is carried out resulting in a low dynamic range and contrast enhanced intensity image. A color restoration process based on relationship between spectral bands and the luminance of the original image is applied to convert the enhanced intensity image back to a color image.

Citation Download Citation

Numan Unaldi, Vijayan K. Asari, and Zia-ur Rahman "Fast and robust wavelet-based dynamic range compression with local contrast enhancement", Proc. SPIE 6978, Visual Information Processing XVII, 697805 (24 April 2008); https://doi.org/10.1117/12.778025

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