A robust C library for embedding and extracting invisible text watermarks in various image formats. It uses DCT-based algorithms for high robustness against cropping and tampering, featuring multi-format support, a command-line tool, and an easy-to-integrate library API.基于 DCT 的鲁棒文本水印 C 语言库，支持多种图片格式，抗裁剪涂抹，含命令行工具。