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Robust image watermarking for diverse channels with template-forming neural network
Watermarking is a key tool in combating unauthorized content distribution, but its effectiveness is often challenged by the wide range of communication channels that can degrade or remove the watermark. We propose a block neural network-based watermarking scheme for digital images that is robust against diverse transmission channels, including compression, pre-processing, and digital-to-analog conversions such as screen photographing and print-scan processes. Instead of using a more conventional encoder-decoder, a neural network with two inputs and inter-layer connectivity is used for forming block templates that are later superimposed into a cover image, while a classification neural network is used for extraction. The method achieves reliable extraction, with an average bit error rate below 20 % even in challenging conditions. It also preserves visual quality (PSNR > 30 dB) and supports a payload of 2 bits per 32 × 32 block, enabling watermark lengths sufficient for unique identification within a single image frame.