Method of extracting digital watermark information and method of judging but value of digital watermark information

• US 6,456,727 B1
• Filed: 03/10/2000
• Issued: 09/24/2002
• Est. Priority Date: 09/02/1999
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Yoshiura, Hiroshi, Anzai, Kousuke, Echizen, Isao, Kurosu, Yutaka
• Primary Examiner(s): Johns, Andrew W.
• Assistant Examiner(s): AZARIAN, SEYED H
• Application Number:
  US09/523,523
• Time in Patent Office: 928 Days
• Field of Search: 382/100, 382/154, 382/117, 382/232, 382/233, 382/295, 382/289, 382/296, 382/275, 345/419, 345/629, 345/634, 235/469, 707/104.1
• US Class Current: 382/100
• CPC Class Codes: G06T 1/0064 Geometric transfor invariant watermarking, e.g. affine transform invariant
• CPC Class Codes: G06T 1/0078 using multiple thresholds
• 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 2201/0065 Extraction of an embedded watermark; Reliable detection

Abstract

A digital watermark information is extracted from geometrically deformed image without using a calibrating digital watermark. Pixel data at positions predetermined in an X-Y coordinate used when embedding the watermark is extracted from image data in which the digital watermark has been embedded for given pixel data and compared with a reference value to determine whether the watermark has been embedded in the pixel data concerned or not. This processing is repeated until it is confirmed that the information is embedded in the pixel data concerned, while applying geometric deformation to the image data.

Claims

1. A digital watermark information extracting method in which digital watermark information is extracted from image data which has the digital watermark information embedded therein by altering at least one pixel data located at a predetermined position on a specific coordinate and is geometrically deformed, comprising:

an embedding position check step of performing the processing of extracting at least one pixel data at a predetermined position on the specific coordinate from the image data and comparing the data value of the pixel data thus extracted with a reference value to judge whether the information is embedded in the pixel data while applying the geometrical deformation on the image data until it is confirmed that the information is embedded in the pixel data;

said embedding position check step comprising;

a roughly checking step of executing the processing of extracting from the image data at least one pixel data located at a predetermined position on the specific coordinate and comparing the data value of the pixel data thus extracted with the reference value to judge whether the information is embedded in the pixel data concerned while the geometrical deformation is applied to the image data by every first geometrical deformation rate which is determined by a size of each of pixel blocks in which the alteration is made, a pitch of the pixel blocks and the number of the pixel blocks until it is confirmed that the information is embedded in the pixel data concerned; and

a detailed checking step of executing the processing of extracting from the image data at least one pixel data located at a predetermined position on the specific coordinate and comparing the data value thus extracted with the reference value to judge whether the information is embedded in the pixel data concerned while the geometrical deformation is applied to the image data by every second geometrical deformation rate smaller than the first geometrical deformation rate within a predetermined range containing the geometrical deformation rate when it is confirmed in said roughly checking step that the information is embedded in the pixel data, until it is confirmed that the information is embedded in the pixel data concerned.

2. A digital watermark information extracting method in which digital watermark information is extracted from image data which has the digital watermark information embedded therein by altering at least one pixel data located at a predetermined position on a specific coordinate and is geometrically deformed, comprising an embedding position check step of executing the processing of extracting at least one pixel data located at a predetermined position on the specific coordinate and comparing the data value of the pixel data thus extracted with a reference value to judge whether the information is embedded in the pixel data concerned while varying the predetermined position on the image data by deforming the specific coordinate until it is confirmed that the information is embedded in the pixel data concerned;

said embedding position check step comprising;

a roughly checking step of executing the processing of extracting from the image data at least one pixel data located at a predetermined position on the specific coordinate and comparing the data value of the pixel data thus extracted with the reference value to judge whether the information is embedded in the pixel data concerned while the predetermined position on the image data is varied by deforming the specific coordinate by every first deformation rate which is determined by a size of each of pixel blocks in which the alteration is made, a pitch of the pixel blocks and the number of the pixel blocks, until it is confirmed that the information is embedded in the pixel data concerned, and

a detailed checking step of executing the processing of extracting from the image data at least one pixel data located at a predetermined position on the specific coordinate and comparing the data value of the pixel data thus extracted with the reference value to judge whether the information is embedded in the pixel data concerned while the predetermined position on the image data is varied by deforming the specific coordinate by every second deformation rate smaller than the first deformation rate within a predetermined range containing the deformation rate when it is confirmed in said roughly checking step that the information is embedded in the pixel data, until it is confirmed that the information is embedded in the pixel data concerned.

3. A storage medium for storing therein a digital watermark information extracting program for extracting digital watermark information from image data in which the digital watermark information is embedded by altering at least one pixel data located at a predetermined position on a specific coordinate and which is geometrically deformed, wherein said program makes an information processor to execute an embedding position check step of performing the processing of extracting at least one pixel data at a predetermined position on the specific coordinate from the image data and comparing the data value of the pixel data thus extracted with a reference value to judge whether the information is embedded in the pixel data while applying the geometrical deformation on the image data until it is confirmed that the information is embedded in the pixel data;

said embedding position check step further comprising;

a roughly checking step of executing the processing of extracting from the image data at least one pixel data located at a predetermined position on the specific coordinate and comparing the data value of the pixel data thus extracted with the reference value to judge whether the information is embedded in the pixel data concerned while the geometrical deformation is applied to the image data by every first geometrical deformation rate which is determined by a size of each of pixel blocks in which the alteration is made, a pitch of the pixel blocks and the number of the pixel blocks until it is confirmed that the information is embedded in the pixel data concerned; and

a detailed checking step of executing the processing of extracting from the image data at least one pixel data located at a predetermined position on the specific coordinate and comparing the data value thus extracted with the reference value to judge whether the information is embedded in the pixel data concerned while the geometrical deformation is applied to the image data by every second geometrical deformation rate smaller than the first geometrical deformation rate within a predetermined range containing the geometrical deformation rate when it is confirmed in said roughly checking step that the information is embedded in the pixel data, until it is confirmed that the information is embedded in the pixel data concerned.

4. A storage medium for storing therein a digital watermark information extracting program for extracting digital watermark information from image data in which the digital watermark information is embedded by altering at least one pixel data located at a predetermined position on a specific coordinate and which is geometrically deformed, wherein said program makes an information processor to execute an embedding position check step of performing the processing of extracting at least one pixel data at a predetermined position on the specific coordinate from the image data and comparing the data value of the pixel data thus extracted with a reference value to judge whether the information is embedded in the pixel data while the predetermined position on the image data is varied by deforming the specific coordinate until it is confirmed that the information is embedded in the pixel data;

said embedding position check step further comprising;

a roughly checking step of executing the processing of extracting from the image data at least one pixel data located at a predetermined position on the specific coordinate and comparing the data value of the pixel data thus extracted with the reference value to judge whether the information is embedded in the pixel data concerned, while changing said predetermined position in the image data by effecting the deformation applied to the specific coordinate by every first deformation rate which is determined by a size of each of pixel blocks in which the alteration is made, a pitch of the pixel blocks and the number of the pixel blocks, until it is confirmed that the information is embedded in the pixel data concerned; and

a detailed checking step of executing the processing of extracting from the image data at least one pixel data located at a predetermined position on the specific coordinate and comparing the data value thus extracted with the reference value to judge whether the information is embedded in the pixel data concerned while changing the predetermined position on the image data by effecting deformation applied to the image data by every second deformation rate smaller than the first deformation rate within a predetermined range containing the deformation rate when it is confirmed in said roughly checking step that the information is embedded in the pixel data, until it is confirmed that the information is embedded in the pixel data concerned.

5. A digital watermark information extracting device for extracting digital watermark information from image data which has the digital watermark information embedded therein by altering at least one pixel data located at a predetermined position on a specific coordinate and is geometrically deformed, comprising:

means of performing the processing of extracting at least one pixel data at a predetermined position on the specific coordinate from the image data and comparing the data value of the pixel data thus extracted with a reference value to judge whether the information is embedded in the pixel data while applying the geometrical deformation on the image data until it is confirmed that the information is embedded in the pixel data;

said embedding position check step further comprising;

a roughly checking step of executing the processing of extracting from the image data at least one pixel data located at a predetermined position on the specific coordinate and comparing the data value of the pixel data thus extracted with the reference value to judge whether the information is embedded in the pixel data concerned while the geometrical deformation is applied to the image data by every first geometrical deformation rate which is determined by a size of each of pixel blocks in which the alteration is made, a pitch of the pixel blocks and the number of the pixel blocks until it is confirmed that the information is embedded in the pixel data concerned; and

a detailed checking step of executing the processing of extracting from the image data at least one pixel data located at a predetermined position on the specific coordinate and comparing the data value thus extracted with the reference value to judge whether the information is embedded in the pixel data concerned while the geometrical deformation is applied to the image data by every second geometrical deformation rate smaller than the first geometrical deformation rate within a predetermined range containing the geometrical deformation rate when it is confirmed in said roughly checking step that the information is embedded in the pixel data, until it is confirmed that the information is embedded in the pixel data concerned.

6. A digital watermark information extracting device for extracting digital watermark information from image data which has the digital watermark information embedded therein by altering at least one pixel data located at a predetermined position on a specific coordinate and is geometrically deformed, comprising means of executing the processing of extracting at least one pixel data located at a predetermined position on the specific coordinate and comparing the data value of the pixel data thus extracted with a reference value to judge whether the information is embedded in the pixel data concerned while varying the predetermined position on the image data by deforming the specific coordinate until it is confirmed that the information is embedded in the pixel data concerned;

said embedding position check step further comprising;

a roughly checking step of executing the processing of extracting from the image data at least one pixel data located at a predetermined position on the specific coordinate and comparing the data value of the pixel data thus extracted with the reference value to judge whether the information is embedded in the pixel data concerned, while changing said predetermined position in the image data by affecting the deformation applied to the specific coordinate by every first deformation rate which is determined by a size of each of pixel blocks in which the alteration is made, a pitch of the pixel blocks and the number of the pixel blocks, until it is confirmed that the information is embedded in the pixel data concerned; and

a detailed checking step of executing the processing of extracting from the image data at least one pixel data located at a predetermined position on the specific coordinate and comparing the data value thus extracted with the reference value to judge whether the information is embedded in the pixel data concerned while changing the predetermined position on the image data by effecting deformation applied to the image data by every second deformation rate smaller than the first deformation rate within a predetermined range containing the deformation rate when it is confirmed in said roughly checking step that the information is embedded in the pixel data, until it is confirmed that the information is embedded in the pixel data concerned.