In recent works, the illumination estimation based on Retinex is utilized to enhance the image details. However, to enhance the image using illumination estimation without affecting the naturalness with non-uniform illumination is very difficult. The usual algorithms used for illumination estimation failed to include these constraints such as sharp edges on illumination boundaries, spatial smoothness, and the limited range of illumination while preserving the naturalness. In this paper, an illumination estimation algorithm using normalized L2\documentclass[12pt]{minimal}
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\begin{document}$$L_2$$\end{document}-Norm with the joint edge-preservation filter is proposed. The proposed algorithm efficiently estimates illumination and fulfils all the above-mentioned constraints. The normalized L2\documentclass[12pt]{minimal}
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\begin{document}$$L_2$$\end{document}-Norm is used to approximate the illumination to overcome the block effect in patch-wise illumination. Then, the overall structure is refined by using the joint edge-preservation filter. Experimental results show the quality of the smoothness of illumination beyond the edges and ensure the range of the estimated illumination in comparison with the other state-of-the-art algorithms.
