Efficient image denoising with heterogeneous kernel-based CNN

Recent advancements in deep learning have notably advanced the field of image denoising. Yet, blindly increasing the depth or width of convolutional neural networks (CNNs) cannot ameliorate the network effectively, and even leads to training difficulties and sophisticated training tricks. In this paper, a lightweight CNN with heterogeneous kernels (HKCNN) is designed for efficient noise removal. HKCNN comprises four modules: a multiscale block (MB), an attention enhancement block (AEB), an elimination block (EB), and a construct block (CB). Specifically, the MB leverages heterogeneous kernels alongside re-parameterization to capture diverse complementary structure information, bolstering discriminative ability and the denoising robustness of the denoiser. The AEB incorporates an attention mechanism that prioritizes salient features, expediting the training stage and boosting denoising efficacy. The EB and CB are designed to further suppress noise and reconstruct latent clean images. Besides, the HKCNN integrates perceptual loss for both retaining semantic details and improving image perceptual quality, so as to refine the denoising output. Comprehensive qualitative and quantitative evaluations highlight the superior performance of HKCNN over state-of-the-art denoising methods, validating its efficacy in practical image denoising scenarios.