Improvement in spread spectrum watermarking through convolutional codes

Abstract

We present a watermarking approach using a directional multiresolution transform named contourlet. Contourlet transform offers a flexible image decomposition at various directions in multiple scales with flexible ratios, then it is easier to determine image areas which are less sensitive to human eye. We combine an spread spectrum scheme with a convolutional coding scheme to improve the capacity of watermark embedded through the host signal. We present some experimental results of our algorithm tested to common signal processing operation, which could be intentional or unintentional.