Digital watermark image processing method

• US 6,584,210 B1
• Filed: 03/23/1999
• Issued: 06/24/2003
• Est. Priority Date: 03/27/1998
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Taguchi, Jun′ichi, Yoshiura, Hiroshi, Takeuchi, Toshifumi, Arai, Takao, Maeda, Akira, Echizen, Isao
• Primary Examiner(s): Patel, Jayanti K.
• Assistant Examiner(s): Choobin, Barry
• Application Number:
  US09/274,103
• Time in Patent Office: 1,554 Days
• Field of Search: 382/100, 382/235, 382/244, 382/254, 235/469, 713/176
• 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 2201/0081 whereby both original and watermarked images are required at decoder, e.g. destination-based, non-blind, non-oblivious
• CPC Class Codes: H04N 1/32203 Spatial or amplitude domain methods H04N1/32309 takes precedence
• CPC Class Codes: H04N 1/32208 involving changing the magnitude of selected pixels, e.g. overlay of information or super-imposition H04N1/32219, H04N1/32224 take precedence
• CPC Class Codes: H04N 1/32235 in highly textured regions
• CPC Class Codes: H04N 1/32251 in multilevel data, e.g. greyscale or continuous tone data

Abstract

An image processing apparatus having an adding unit to add information by changing a data value of image data and a detecting unit to detect the information added to the image data. In a digital watermark image processing method in the image processing apparatus, filter passage image data is formed by performing an image filtering process to original image data, watermark core image data is formed by performing a process to obtain a difference between the filter passage image data and the original image data, change amount image data is formed by performing a process to obtain a value to change the data value of the image data on the basis of the watermark core image data and desired information to be added, and watermark inserted image data is formed by performing a process to add the original image data and the change amount image data.

Claims

1. A digital watermark image processing method in an image processing apparatus having means for adding information by changing a data value of image data and means for detecting the information added to said image data, comprising the steps of:

forming filter passage image data by performing an image filtering process to original image data;

forming watermark core image data by performing a process to obtain a difference between said filter passage image data and said original image data;

forming change amount image data by performing a process to obtain a value to change a data value of said original image data on the basis of said watermark core image data and desired information to be added; and

forming watermark inserted image data by performing a process to add said original image data and said change amount image data.

2. A method according to claim 1, wherein when said change amount image data is formed by performing the process to obtain the value to change the data value of said original image data on the basis of said watermark core image data and said desired information to be added,

information adding position image map data is formed by performing a process to select an image position where the information should be added on the basis of the data value of said watermark core image data.

5. A method according to claim 2, wherein when said desired information to be added is expressed by a bit train of “

0” and

“

1”

, said change amount image map data is formed from said bit train of “

0” and

“

1”

with reference to said information adding position image map data by a predetermined method.

6. A method according to claim 5, wherein in the process to form said change amount image map data from said bit train of “

0” and

“

1”

with reference to said information adding position image map data by the predetermined method, bit corresponding position image map data showing a correspondence such that the bit of which number from the first bit in said bit train of “

0” and

“

1”

becomes the information that is added to which image position is formed.

7. A method according to claim 1, wherein

positive value addable image data and negative value addable image data are formed on the basis of said watermark core image data, and

an averaging process of said positive value addable image data and said negative value addable image data is performed, thereby forming difference discrimination image data.

8. A method according to claim 7, wherein said change amount image data is formed on the basis of said desired information to be added with reference to said positive value addable image data and said negative value addable image data.

9. A method according to claim 1, wherein an edge preserving type image filtering process is used as said image filtering process.

10. A method according to claim 9, wherein a one-dimensional smoothing type filtering process in a minimum changing direction is used as said edge preserving type image filtering process.

11. A method according to claim 7, wherein

when said watermark inserted image data or image data obtained by modifying said watermark inserted image data is used as watermark detecting image data,

difference comparison image data is formed by performing a process to obtain a difference between said watermark detecting image data and said original image data, and

a data value of said difference comparison image data and a data value of said difference discrimination image data are compared, thereby reading the information added to said watermark detecting image data.

12. A method according to claim 11, wherein with respect to the case where said bit corresponding position image map data disclosed in claim 6 is formed,

when the data value of said difference comparison image data and the data value of said difference discrimination image data are compared, the bit corresponding position image map data is referred.

3. A digital watermark image processing method in an image processing apparatus having means for adding information by changing a data value of image data and means for detecting the information added to said image data, comprising the steps of:

forming filter passage image data by performing an image filtering process to original image data;

forming watermark core image data by performing a process to obtain a difference between said filter passage image data and said original image data;

forming change amount image data by performing a process to obtain a value to change a data value of said original image data on the basis of said watermark core image data and desired information to be added; and

forming watermark inserted image data by performing a process to add said original image data and said change amount image data,

wherein when said change amount image data is formed by performing the process to obtain the value to change the data value of said original image data based on said watermark core image data and said desired information to be added,

information adding position image map data is formed by performing a process to select an image position where the information should be added based on the data value of said watermark core image data,

wherein when the information adding position image map data is formed by performing the process to select the image position where the information should be added based on the data value of said watermark core image data, and

wherein if a data value of a target pixel of the information adding position image map data denotes that the information has been added, the case of adding the information in an interlocking relation therewith is excluded and, with respect to predetermined peripheral pixels of said target pixel, said information adding position image map data is formed so that each of the data values of the information adding position image map data is equal to a value showing that no information is added or said state is satisfied even if attention is paid to an arbitrary pixel.

4. A method according to claim 3, wherein as a method of forming said information adding position image map data, whether said information adding position image map data is sequentially changed in accordance with the order of selecting the positions of the images where the information should be added or not is discriminated on the basis of the data value of said watermark core image data as a reference,

if the value of said information adding position image map data at said image position to be subjected to said discrimination is equal to an initial state value, it is determined that the information can be added, the data value of said information adding position image map data is changed to a data value showing that the information is added, further, the position to be subjected to said discrimination is used as a reference, each of the data values of said information adding position image map data in said predetermined peripheral pixel range is changed to a data value showing that data exists at positions near said position,

if the value of said information adding position image map data at the image position to be subjected to said discrimination is not equal to the initial state value, it is determined that the information cannot be added, and the data value of said information adding position image map data is not changed.