Transform domain image watermarking method and system

A method of watermarking a digitized image for subsequent authentication, said digitized image comprising spatial domain data signals and being reproduced from an original image, said method including the steps of:

• transforming said spatial domain data signals into frequency domain data signals including respective magnitude and phase data signal components;
• embedding information signals into said magnitude data signals to develop modified data signals;
• and
• converting said modified data signals from said frequency domain to said spatial domain to generate said watermarked digitized image.

A watermarking apparatus for tagging a digitized image for subsequent authentication, said digitized image comprising spatial domain data signals and being reproduced from an original image, said apparatus including:

• a transformer, said transformer operating to transform said spatial domain data signals into frequency domain data signals, including respective magnitude and phase data signal components;
• a processor disposed to receive the output of said transformer, said processor being operative to embed information signals into said magnitude data signals to develop modified data signals;
• and
• a converter located to receive the output of said processor, said converter operative to convert said modified data signals from said frequency domain to said spatial domain to generate said watermarked digitized image.

A digitized image authentication system for implanting and detecting watermark information in a digitized reproduction of an image, said digitized image comprising spatial domain data signals and being reproduced from an original image, said system including:

• a watermarking apparatus for tagging said digitized image signals, said apparatus including
• a transformer located to receive said spatial domain data signals, said transformer operative to transform said spatial domain data signals into frequency domain data signals including respective magnitude and phase data signal components;
• a processor disposed at the output of said transformer, said processor being operative to embed information into said magnitude data signals to develop modified data signals;
• a converter positioned to receive the output of said processor, said converter being operative to convert said modified data signals from said frequency domain to said spatial domain to generate said watermarked digitized image signals;
• and
• a watermark recovery apparatus for authenticating said tagged digitized image, said recovery apparatus including:
• a transformer located to receive said spatial domain data signals comprising said respective images, said transformer being operative to transform said spatial domain data signals into respective frequency domain dataset signals;
• and
• a comparator receiving said respective frequency dataset signals from said transformer, said comparator being operative to compare said respective frequency domain dataset signals to identify said watermark and verify the authenticity of said image reproduction.