Fig. 4

The example of rotation search. a is the feature region without rotation and the location of embedded watermark. b is the captured feature region with 50° rotation, in comparison with the feature region without rotation. They do not match with each other. c is the captured feature region after being re-rotated at 20°, in comparison with the feature region without rotation. They do not match with each other. d is the captured feature region after being re-rotated at 40°, in comparison with the feature region without rotation. They have a great matching