Hiding binary logo with DCT-based digital watermarking

In this paper, we describe a watermarking technique for hiding a confidential two-dimension binary watermark, such as a company logo, into a still image. Our technique is applied to the frequency domain of the image obtained by two-dimension DCT. The watermark is embedded with a secret key into the low frequency and stored according to a zigzag format. The extraction of the watermark can be performed without knowledge of the original image, but the correct secret key is needed. Finally, since the transform domain algorithm to encode the watermark information is used, the information is robust enough against JPEG compression and ordinary image processing.