Digital watermarking

• US 6,724,913 B1
• Filed: 09/21/2000
• Issued: 04/20/2004
• Est. Priority Date: 09/21/2000
• Status: Active Grant

• Current Assignee: Wen-Hsing Hsu
• Original Assignee: Wen-Hsing Hsu
• Inventors: Chen, Trista, Hsu, Wen-Hsing
• Primary Examiner(s): Patel, Jayanti K.
• Assistant Examiner(s): Tabatabai, Abolfazl
• Application Number:
  US09/666,294
• Time in Patent Office: 1,307 Days
• Field of Search: 382/100, 382/232, 382/115, 382/240, 380/51, 380/54, 380/59, 380/210, 380/252, 380/287, 380/201, 381/73.1, 704/273, 709/217, 713/176, 713/179, 348/460, 348/461, 348/463, 370/522, 370/523, 370/524, 370/525, 370/526, 370/527, 370/528, 370/529, 283/74, 283/75, 283/76, 283/77, 283/78, 283/79, 283/81, 283/85, 283/93
• US Class Current: 382/100
• CPC Class Codes: G06T 1/005 Robust watermarking, e.g. average attack or collusion attack resistant
• CPC Class Codes: G06T 1/0092 Payload characteristic determination in a watermarking scheme, e.g. number of bits to be embedded
• CPC Class Codes: G06T 2201/0052 Embedding of the watermark in the frequency domain

Abstract

A watermarking method and device to embed a digitized watermark into a digital image file in the transformation domain is disclosed. In the watermarking technology of this invention, the digitized watermark is first error corrected to enhance its robustness. The digital image file to be embedded with the digitized watermark is first processed such that capacity of each element of the digital image file is calculated. The capacity of an element of the digital image file represents the highest value of tolerance for an element of the watermark to be added to the said element of the digital image file. Elements of the digital image file to which watermark elements may be added are selected and their addresses are recorded. The selected elements are then modulated so that they are suited to be embedded with elements of the digital watermark. After modulation the digitized watermark is embedded into the digital file by distributing the modulated elements of the watermark into the selected addresses. A 3*3 mask is used to calculate the capacity of each element of the digital image file.

Claims

1. A method to embed into a digitized file a watermark, comprising:

obtaining a modulated digitized image file;

obtaining a modulated digitized watermark file;

allocating in said digitized image file portions where human sense is less sensible to additional data being added into said portions; and

adding into at least a part of said portions data representing said modulated digitized watermark file,

wherein said step of allocating portions where human sense is less sensible to additional data being added comprises allocating elements in the transformation domain of said digitized image file to which additional data may be added with less sensibility by human sense, and also comprises the steps of;

calculating capacity values of all elements in the transform domain of said digitized image file to obtain a matrix of said capacity values, said capacity values representing a power of resistance to noises of said elements;

calculating, according to values and positions of said capacity values in said matrix of capacity values, human-sensibility values corresponding to each of said capacity values to obtain a matrix of human-sensibility values; and

labeling in said matrix of human-sensibility values elements with human-sensibility values greater than a predetermined threshold.

2. The method according to claim 1 wherein said step of calculating human-sensibility values comprises multiplication of power factors under JPEG standard and a quantization matrix under JPEG standard.

3. The method according to claim 1, further comprising a step of scaling said capacity values to be within a predetermined scope.

4. The method according to claim 1, further comprising a step of adjusting said human-sensibility values with noise values which may be brought to said digitized image file during processing and quantization.

5. The method according to claim 1 wherein said step of calculating said human-sensibility values comprises calculating the sum of multiplying values of each element in the transformation domain of said digitized image file and values of elements surrounding said element with a 3*3 mask.

6. The method according to claim 5 wherein values of elements of said 3*3 mask are

7. The method according to claim 1 wherein said step of adding into said digitized watermark file further comprises adjusting values of elements of said digitized watermark with scaling factors.

8. A device for processing of a digitized image file wherein operation of said device comprises:

obtaining a modulated digitized image file;

obtaining a modulated digitized watermark file;

allocating in said digitized image file portions where human sense is less sensible to additional data being added into said portions; and

adding into at least a part of said portions data representing said modulated digitized watermark file,

wherein said operation of allocating portions where human sense is less sensible to additional data being added comprises allocating elements in the transformation domain of said digitized image file to which additional data may be added with less sensibility by human sense, and also comprises the operations of;

calculating capacity values of all elements in the transform domain of said digitized image file to obtain a matrix of said capacity values, said capacity values representing a power of resistance to noises of said elements;

calculating, according to values and positions of said capacity values in said matrix of capacity values, human-sensibility values corresponding to each of said capacity values to obtain a matrix of human-sensibility values; and

labeling in said matrix of human-sensibility values elements with human-sensibility values greater than a predetermined threshold.

9. The device according to claim 8 wherein said operation of calculating human-sensibility values comprises multiplication of power factors under JPEG standard and a quantization matrix under JPEG standard.

10. The device according to claim 8 wherein said operation of calculating said human-sensibility values comprises calculating the sum of multiplying values of each element in the transformation domain of said digitized image file and values of elements surrounding said element with a 3*3 mask.

11. The device according to claim 10 wherein values of elements of said 3*3 mask are

12. The device according to claim 8 wherein said operation of adding into said digitized watermark file further comprises adjusting values of elements of said digitized watermark with scaling factors.