Counteracting geometric distortions in watermarking
View Patent ↗A digital watermarking method receives multimedia data, such as images or audio, in compressed or uncompressed form, and extracts a digital watermark while counteracting geometric distortions. To counteract geometric distortion, a watermark reading process translates the data before extracting the digital watermark. The reading process operates on compressed data such as JPEG or MPEG images, which are comprised of compressed blocks of image data.
1. A method for exacting a watermark from data containing a watermark comprising:
receiving data containing a watermark including a plural-bit message and at least one steganographic component;
with reference to the steganographic component, determining a registration associated with the data or component; and
extracting the plural-bit message of the watermark with at least consideration of the registration.
2. A method for extracting a watermark from data containing a watermark as set forth in claim 1 , further comprising adjusting the data with at least a geometric transform.
3. A method for extracting a watermark from data containing a watermark as set forth in claim 1 , wherein the watermark is extracted from data blocks each comprising an n by n block where the value of n is 8.
4. The method of claim 1 wherein the registration pertains to at least one of scale, rotation and orientation.
5. The method of claim 1 wherein rite steganographic component comprises at least a predetermined pattern.
6. The method of claim 1 wherein the steganographic component comprises at least a message carrier.
7. A method of extracting a watermark from compressed data containing a watermark comprising:
receiving compressed data containing a watermark in the form of n by n blocks, which data has been subjected to distortion;
transforming the data;
determining a calibration of the transformed data based on characteristics of a steganographic calibration component associated with the watermark; and
extracting the watermark from the transformed data based at least in part on the calibration.
8. The method of claim 7 wherein the characteristics of the steganographic orientation component evidences at least one of scale, rotation and registration.
9. The method of claim 7 wherein the steganographic calibration component comprises at least a pattern.
10. The method of claim 7 wherein the steganographic calibration component comprises at least a message carrier.