Abstract
Digital watermarking technique has been proposed for years to actualize copyright protection for digital data. Digital data can refer to audio, image, and video. In this thesis, we discuss only embedding watermarks into images.Previous works have been used to look for the position to place the watermarks based on mathematical methods. Instead of proposing a new embedding method, this thesis proposes a watermark structure. A good watermark structure can also strengthen the robustness of a watermark.Some researchers embedded a sequence of random numbers and some others embedded visually recognizable patterns into images. This thesis studies using a meaningful character string with error-correcting codes as watermarks to insert into an image. Experiments to insert and extract watermarks are given. The detections of watermarks due to several attacks are also examined.