Structural compensation enhancement method for nonuniform illumination images

A structural compensation enhancement method is proposed to resolve the issue of nonuniform illumination image enhancement. A logarithmic histogram equalization transformation (LHET) is developed for improving the contrast of image and adjusting the luminance distribution. A structural map of illumination compensation is produced with a local ambient light estimation filter. The enhanced image is obtained by nonlinearly fusing the LHET result, reflection component, and structural map of illumination compensation. Unlike existing techniques, the proposed method has the ability of two-way adjustment for brightness. Furthermore, the proposed method can effectively enhance the nonuniform illumination images with a balance between visibility and naturalness. Extensive experimental comparisons with some state-of-the-art methods have shown the superior performance of the proposed method.