The thesis presents a robust lossless watermarking technique, based on α-trimmed mean algorithm and Support Vector Machine (SVM), for image authentication. The technique does not damage the contents of original images during watermark embedding because it first trains an SVM to memorize relationship between the watermark and the image-dependent signature, and then exploits the trained SVM to estimate the watermark. Meanwhile, its robustness can be enhanced by using α-trimmed mean operator against attacks. Experimental results demonstrate that the technique not only possesses the robust ability to resist on image-manipulation attacks under consideration but also, in average, is superior to other existing methods being considered in the paper.