Image analysis – Image transformation or preprocessing – Measuring image properties
Reexamination Certificate
1999-12-01
2004-03-23
Wu, Jingge (Department: 2623)
Image analysis
Image transformation or preprocessing
Measuring image properties
C382S286000, C382S278000, C382S296000, C382S298000, C382S100000, C382S205000, C358S003280
Reexamination Certificate
active
06711303
ABSTRACT:
FIELD OF THE INVENTION
The invention relates generally to the field of image processing, and in particular to methods for detecting when an image has been rotated or resized (magnified).
BACKGROUND OF THE INVENTION
U.S. Pat. No. 5,835,639 issued Nov. 10, 1998 to Honsinger et al., entitled “Method For Detecting Rotation And Magnification In Images” describes a method for embedding two identical carriers in an image in order to track rotation and magnification changes. The method is based on the fact that the autocorrelation of the image will contain the cross-correlation of the two carriers and the cross-correlation will exhibit two delta functions whose distance apart will be proportional to magnification and whose angle will be maintained under no rotation or will be rotated in the same amount as the rotation of the original image. Thus, by identifying the location (separation and rotation) of the two delta functions one can determine the amount of rotation and magnification that an image has undergone. In images that contain a large amount of pronounced linear and angular features, these features tend to cause the autocorrelation of the image to exhibit a number of features that mask the delta functions, thereby making the detection of the delta functions difficult.
There is a need therefore for an improved method of detecting angular rotation and magnification of the type disclosed in the above referenced patent that avoids this problem.
SUMMARY OF THE INVENTION
The present invention is directed to overcoming one or more of the problems set forth above. Briefly summarized, according to one aspect of the present invention an improved method and computer program product for detecting an amount of rotation or magnification in a modified image, of the type including the steps of:
a) embedding a marker image having a pair of identical features separated by a distance d and oriented at an angle &agr; in an original image to produce a marked image, the marked image having been rotated and/or magnified to produce the modified image;
b) performing an autocorrelation on the modified image to produce a pair of autocorrelation peaks corresponding to the location of the features of the marker image in the modified image; and
c) comparing the separation d and orientation &agr; of the autocorrelation peaks with the separation d and orientation &agr; of the features in the marker image to determine the amount of rotation and magnification in the modified image, wherein the improvement comprises the step of:
d) preprocessing the modified image to have a constant standard deviation over all local regions in the image.
The present invention has the advantage of being able to more easily detect the autocorrelation peaks in an image having large amounts of linear and angular detail.
These and other aspects, objects, features and advantages of the present invention will be more clearly understood and appreciated from a review of the following detailed description of the preferred embodiments and appended claims, and by reference to the accompanying drawings.
REFERENCES:
patent: 3749919 (1973-07-01), Kegelman
patent: 4084255 (1978-04-01), Casasent et al.
patent: 4571635 (1986-02-01), Mahmoodi et al.
patent: 5185815 (1993-02-01), Brandstetter
patent: 5533149 (1996-07-01), Kaplan et al.
patent: 5734801 (1998-03-01), Noguchi et al.
patent: 5822458 (1998-10-01), Silverstein et al.
patent: 5835639 (1998-11-01), Honsinger et al.
patent: 5852678 (1998-12-01), Shiau et al.
patent: 5887084 (1999-03-01), Wober et al.
patent: 5982915 (1999-11-01), Doi et al.
patent: 6014471 (2000-01-01), Barkan et al.
patent: 6091243 (2000-07-01), Xiang et al.
patent: 6219462 (2001-04-01), Anandan et al.
patent: 6341180 (2002-01-01), Pettersson et al.
patent: 6385329 (2002-05-01), Sharma et al.
patent: WO 9910832 (1999-03-01), None
patent: WO 99/12347 (1999-03-01), None
Geert Depovere et al., Improved Watermark Detection Reliability Using Filtering Before Correlation, 1998 IEEE, pp. 430-434.
Hsin-Chih Lin et al., Extracting Periodicity of a Regular Texture Based on Autocorrelation Functions, Pattern Recognition Letter 18 (1997) pp. 433-443.
Eastman Kodak Company
Hesseltine Ryan J.
Watkins Peyton C.
Wu Jingge
LandOfFree
Method and computer program for detecting rotation and... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and computer program for detecting rotation and..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and computer program for detecting rotation and... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3190472