Patent ID: 7697716

Claim:
In a method of digitally watermarking an image by changing aspects thereof to steganographically convey a plural-bit payload, an improvement comprising: receiving image data representing a pattern of elements of differing spatial sizes but of uniform color; applying a first filtering function to said image data to identify a first portion of the image represented thereby, said first portion comprising one or more regions having image elements within a first range of sizes; applying a digital watermarking procedure to said first portion of the image using a first watermarking intensity; applying a second filtering function to said image data to identify a second portion of the image represented thereby, said second portion comprising one or more regions having image elements within a second range of sizes; applying a digital watermarking procedure to said second portion of the image using a second watermarking intensity greater than the first; wherein the method includes performing said watermarking procedures using a computer that is programmed to perform said procedures pursuant to instructions from program software.