A homotopy-CNN framework for continuous deformation in low-light image enhancement.

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Bibliographic Details
Title: A homotopy-CNN framework for continuous deformation in low-light image enhancement.
Authors: Shivam Kumar Jha, S. (AUTHOR), Mohana, N. (AUTHOR)
Source: Connection Science. Dec 2025, Vol. 37 Issue 1, p1-11. 11p.
Subjects: Convolutional neural networks, Image enhancement (Imaging systems), Image processing, Image quality analysis, Homotopy theory, Contrast effect
Abstract: In this paper, we propose a homotopy-guided image enhancement framework for Low-Light Image Enhancement (LLIE), where a low-light image is progressively transformed into a well-lit version using a parametric deformation model. The enhancement pipeline incorporates a convolutional neural network that predicts structure-aware filtering parameters, which are applied via a 12-directional convolution kernel fusion, followed by adaptive gamma, contrast, and saturation refinements. Instead of relying solely on reference-free or black-box learning, the model leverages perceptual quality metrics such as SSIM and PSNR during training to optimise enhancement along the homotopy path. Notably, we explore the modulation of brightness across the range $ b \in [-2.0, 2.0] $ b ∈ [ − 2.0 , 2.0 ] , observing that $ b \leq 0 $ b ≤ 0 yields outputs closer to ground-truth references, while $ b \geq 0 $ b ≥ 0 enhances perceptual vividness. Experiments on the LOL dataset show that the method produces superior visual quality and strong quantitative performance, all while remaining efficient on standard CPUs without the need for GPU acceleration. [ABSTRACT FROM AUTHOR]
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Database: Psychology and Behavioral Sciences Collection
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Abstract:In this paper, we propose a homotopy-guided image enhancement framework for Low-Light Image Enhancement (LLIE), where a low-light image is progressively transformed into a well-lit version using a parametric deformation model. The enhancement pipeline incorporates a convolutional neural network that predicts structure-aware filtering parameters, which are applied via a 12-directional convolution kernel fusion, followed by adaptive gamma, contrast, and saturation refinements. Instead of relying solely on reference-free or black-box learning, the model leverages perceptual quality metrics such as SSIM and PSNR during training to optimise enhancement along the homotopy path. Notably, we explore the modulation of brightness across the range $ b \in [-2.0, 2.0] $ b ∈ [ − 2.0 , 2.0 ] , observing that $ b \leq 0 $ b ≤ 0 yields outputs closer to ground-truth references, while $ b \geq 0 $ b ≥ 0 enhances perceptual vividness. Experiments on the LOL dataset show that the method produces superior visual quality and strong quantitative performance, all while remaining efficient on standard CPUs without the need for GPU acceleration. [ABSTRACT FROM AUTHOR]
ISSN:09540091
DOI:10.1080/09540091.2025.2546911