Adaptive multi-scale contrast enhancement through non-linear pyramid recombination

This paper presents an adaptive contrast enhancement technique based on a hierarchical image representation. First a linear multi-scale image decomposition is obtained by computing a ratio of low-pass pyramid. Thereafter the input image is reconstructed by non-linear multiplication of successive pyramid layers. The recombination process adaptively stretches local image contrast at all levels of resolution. This results in an overall contrast enhancement of the recombined image. Moreover, the reconstructed image can become independent of changes in lighting and luminance gradients.