Methods for digital watermarking of images and images produced thereby

• US 7,046,820 B2
• Filed: 07/16/2002
• Issued: 05/16/2006
• Est. Priority Date: 07/16/2002
• Status: Expired due to Fees

• Current Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Original Assignee: Matsushita Electric Industrial Company Limited (Panasonic Holdings Corporation)
• Inventors: Yu, Hong Heather
• Primary Examiner(s): Wu, Jingge
• Assistant Examiner(s): MACKOWEY, ANTHONY M
• Application Number:
  US10/195,233
• Publication Number:
  US 20040013284A1
• Time in Patent Office: 1,400 Days
• Field of Search: 382/100, 358/3.28
• US Class Current: 382/100
• CPC Class Codes: G06T 1/0028 Adaptive watermarking, e.g. Human Visual System [HVS]-based watermarking
• CPC Class Codes: G06T 2201/0051 Embedding of the watermark in the spatial domain
• CPC Class Codes: G06T 2201/0061 Embedding of the watermark in each block of the image, e.g. segmented watermarking
• CPC Class Codes: G06T 2201/0083 whereby only watermarked image required at decoder, e.g. source-based, blind, oblivious

Abstract

The computer analyzes a representation of a digitized image to determine contiguous edges of the image; select edges for modulation in accordance with a data hiding criterion; apply a watermark-dependent edge point modulation to pixels on the selected edges; and wherein said analyzing to determine contiguous edges produces lists of pixel pointers, each list containing pointers to pixel locations of a contiguous edge; and wherein said criterion selects lists corresponding to low contrast, low smoothness edges.

Claims

1. A method for watermarking an image utilizing a computer, said method comprising utilizing the computer to:

analyze a representation of a digitized image to determine contiguous edges of the image;

select edges for modulation in accordance with a data hiding criterion;

apply a watermark-dependent edge point modulation to pixels on the selected edges; and

wherein said analyzing to determine contiguous edges produces lists of pixel pointers, each list containing pointers to pixel locations of a contiguous edge; and

wherein said criterion selects lists corresponding to low contrast, low smoothness edges.

2. A method in accordance with claim 1 wherein said applying an edge point modulation comprises embedding a repetition coded watermark.

3. A printed watermarked image produced in accordance with the method of claim 1.

4. A method for watermarking an image utilizing a computer, said method comprising utilizing the computer to:

analyze a representation of a digitized image to determine contiguous edges of the image;

select edges for modulation in accordance with a data hiding criterion;

apply a watermark-dependent edge point modulation to pixels on the selected edges; and

wherein said analyzing to determine contiguous edges produces lists of pixel pointers, each list containing pointers to pixel locations of a contiguous edge;

wherein said criterion selects lists corresponding to low contrast, low smoothness edges; and

wherein said applying a watermark-dependent edge point modulation comprises replacing a pixel e of an edge with a new pixel e′

having a value δ

*W(G)*(b−

a)+a, where δ

is a modulation level, W(G) is the Gth bit in a binary watermark stream W, a is a value corresponding to a metric used to describe color in a color space of the digitized image for the edge pixel _e, and _b is a value of an adjacent pixel in an approximately normal direction.

5. A method for watermarking an image utilizing a computer, said method comprising utilizing the computer to:

analyze a representation of a digitized image to determine contiguous edges of the image;

select edges for modulation in accordance with a data hiding criterion;

apply a watermark-dependent edge point modulation to pixels on the selected edges;

wherein said analyzing to determine contiguous edges produces lists of pixel pointers, each list containing pointers to pixel locations of a contiguous edge;

wherein said criterion selects lists corresponding to low contrast, low smoothness edges;

wherein said applying a watermark-dependent edge point modulation comprises replacing a pixel e of an edge with a new pixel e′

having a value δ

*W(G)*(b−

a)+a where δ

is a modulation level, W(G) is the Gth bit in a binary watermark stream W, a is a value corresponding to a metric used to describe color in a color space of the digitized image for the edge pixel _e, and _b is a value of an adjacent pixel in an approximately normal direction; and

shuffle said pixel pointers pseudorandomly.

6. A method for watermarking an image utilizing a computer, said method comprising utilizing the computer to:

analyze a representation of a digitized image to determine border lines within an image;

select border lines for modulation in accordance with a data hiding criterion; and

apply a watermark-dependent border point modulation to pixels in the selected border lines;

wherein said analyzing to determine border lines produces lists of pixel pointers, each list containing pointers to pixel locations of a border line; and

wherein said criterion selects lists corresponding to low smoothness borders.

7. A printed watermarked image produced in accordance with the method of claim 6.

8. A method in accordance with claim 6 wherein said applying a border point modulation comprises embedding a repetition coded watermark.

9. A method for watermarking an image utilizing a computer, said method comprising utilizing the computer to:

analyze a representation of a digitized image to determine border lines within an image;

select border lines for modulation in accordance with a data hiding criterion; and

apply a watermark-dependent border point modulation to pixels in the selected border lines;

wherein said analyzing to determine border lines produces lists of pixel pointers, each list containing pointers to pixel locations of a border line;

wherein said criterion selects lists corresponding to low smoothness borders; and

wherein said applying a watermark-dependent edge point modulation comprises replacing a pixel e of an edge with a new pixel e′

having a value e′

=e·

K′

[J]+(K[J]+e·

K[J])·

W[G], where K[J] is the Jth value in a key array K, K′

[J] is the complement of K[J], and W(G) is the Gth watermark symbol from watermark stream W.

10. A method for watermarking an image utilizing a computer, said method comprising utilizing the computer to:

analyze a representation of a digitized image to determine border lines within an image;

select border lines for modulation in accordance with a data hiding criterion; and

apply a watermark-dependent border point modulation to pixels in the selected border lines;

wherein said analyzing to determine border lines produces lists of pixel pointers, each list containing pointers to pixel locations of a border line;

wherein said criterion selects lists corresponding to low smoothness borders; and

wherein said applying a watermark-dependent edge point modulation comprises replacing a pixel e of an edge with a new pixel e′

having a value e′

=e·

K′

[J]+(K[J]+e·

K[J])·

W[G], where K[J] is the Jth value in a key array K, K′

[J] is the complement of K[J], and W(G) is the Gth watermark symbol from watermark stream W; and

shuffle said pixel pointers pseudorandomly.