A Gradient Invariant DCT-Based Image Watermarking Scheme for Object Detection

In this paper, we proposed a novel DCT-based watermarking scheme for grayscale images, which utilizes the connection between discrete cosine transform (DCT) and the Histogram of Oriented Gradient (HOG) feature extraction operation. We embed messages into the low-frequency band, and correspondingly, an effective coefficients pair selection scheme is constructed. The proposed scheme not only maintains the superiority of compression robustness but also keeps good visual quality for the watermarked image. Moreover, the proposed method is insensitive to HOG feature extraction, which makes the watermarked image more suitable for further objection detection and recognition scenarios.