ABSTRACT
This chapter discusses a new blind image watermarking algorithm robust against both affine transformations and JPEG compression. It introduces Watermark embedding in “Watermark Embedding” and describes the watermark extraction based on resynchronization in “Watermark Extraction with Resynchronization”. A serious problem constraining some practical exploitations of watermarking technology is the insufficient robustness of existing watermarking algorithms against geometrical distortions such as translation, rotation, scaling, cropping, change of aspect ratio, and shearing. Discrete wavelet transform (DWT) is playing an increasingly important role in watermarking, due to its good spatial-frequency characteristics and its wide applications in the image and video coding standards. By comparing the detected template with the originally embedded template, we can determine the affine transformation possibly applied to the test image. The watermarking scheme embeds a template in magnitude spectrum in the discrete Fourier transformation domain to resist affine transform and uses a training sequence embedded in the DWT domain to achieve synchronization against translation.
