Adaptive image enhancement through quantum variance maximization

This paper presents a quantum-inspired image enhancement framework, termed Adaptive Image Enhancement through Quantum Variance Maximization (AIEQVM). The proposed method employs the Flexible Representation of Quantum Images (FRQI) to encode image intensities as quantum rotation angles and formulates image enhancement as a block-wise variance maximization problem. An adaptive enhancement parameter is determined for each image block through bounded scalar optimization, followed by a nonlinear quantum-inspired intensity transformation. To ensure spatial consistency and suppress block artifacts, the optimized enhancement map is smoothed before image reconstruction. The proposed framework is evaluated on benchmark natural images Palm, Garden, Car, a Brain MRI image, and a low-light Flowers image, and is compared with Histogram Equalization (HE) and Contrast Limited Adaptive Histogram Equalization (CLAHE). Performance is assessed using both full-reference and no-reference quality metrics, including Variance, Contrast Improvement Index (CII), Entropy, PSNR, SSIM, NIQE, BRISQUE, and LPIPS. Experimental results demonstrate that AIEQVM consistently achieves superior contrast enhancement while preserving structural information and perceptual image quality. Compared with conventional histogram-based enhancement methods, the proposed approach provides improved balance between contrast enhancement and artifact suppression, yielding higher structural similarity together with competitive perceptual quality across diverse imaging conditions. These results demonstrate the effectiveness of quantum-inspired variance optimization for adaptive image enhancement and highlight its potential for both natural and medical image processing. The source code used to implement the proposed Adaptive Image Enhancement through Quantum Variance Maximization (AIEQVM) method and to reproduce the reported experiments is publicly available at https://github.com/Johnchristopherclement/Adaptive_Image_Enhancement_Through_Quantum_Variance_Maximization