ลายน้ำดิจิตอลสำหรับรูปภาพที่คืนสภาพได้จากการหมุน การปรับขนาดและการเคลื่อนที่ โดยใช้ฟังก์ชันเอ็กซ์โพเนนเชียลเชิงซ้อน / สิริพร ผลสมบูรณ์ = Rotation, scale, and translation resilient digital image watermarking based on complex exponential function / Siriporn Pholsomboon
In this thesis, a novel digital image watermarking scheme has been proposed based on spread spectrum technique. By exploiting complex exponential function to generate a multiplering shaped pattern, the watermark is invariant to rotation and translation, and is resilient to scaling without the need of inverse transformation. The proposed technique is performed in frequency domain without additional Log-Polar mapping. This technique reduces computational complexity of such transformation. Furthermore, the original image is not needed in the detection process. Therefore, the computational time to search for the original image and the space needed to keep the image are reduced. Experimental results demonstrate the validity of the proposed scheme. The watermark is correctly detected although the image was undergone by various geometric and non-geometric transformations.
