Image attribute altering device and electronic watermark embedding device

• US 6,668,068 B2
• Filed: 05/14/1999
• Issued: 12/23/2003
• Est. Priority Date: 05/15/1998
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Hashimoto, Masahiro
• Primary Examiner(s): Patel, Jayanti K.
• Assistant Examiner(s): CHAWAN, SHEELA C
• Application Number:
  US09/313,543
• Publication Number:
  US 20030138126A1
• Time in Patent Office: 1,684 Days
• Field of Search: 382/100, 382/250, 382/239, 382/235, 382/232, 380/201, 380/235, 380/255, 380/202, 380/51, 380/217, 380/207, 380/268, 380/206, 380/203, 283/43
• US Class Current: 382/100
• CPC Class Codes: G06T 1/0021 Image watermarking
• CPC Class Codes: H04N 2005/91335 the copy protection signal being a watermark
• CPC Class Codes: H04N 5/913 for scrambling ; for copy protection

Abstract

Image attribute detection means for detecting the attribute of an input image (attribute “A”) and image attribute altering means for altering the image attribute in the input image on the basis of the attribute detection result of the input image are provided to output an output image having a new attribute (attribute “B”). The image attribute detection means includes first DCT means for subjecting the input image to discrete cosine transform to obtain frequency components, second DCT means for subjecting the original image to discrete cosine transform to obtain original frequency components, and means of subtracting the original frequency components from the image frequency components and dividing the subtraction result by the image frequency components to detect the electronic watermark data.

Claims

1. An electronic watermark embedding device comprising:

discrete cosine transform means for subjecting an input image to discrete cosine transform;

electronic watermark detection means for detecting whether electronic watermark data to be inserted by an electronic watermark embedding means have been already inserted in the input image;

electronically embedding means for inserting electronic watermark data into input image data converted by the discrete cosine transform means; and

selection means for directly outputting the input image with no modification when it is detected by said electronic watermark detection means that the electronic watermark data has been inserted in the input image, or embedding new electronic watermark data into the input image when the insertion of the electronic watermark data is not detected,

wherein said electronic watermark detection means performs the following operations;

on the assumption that the original image and electronic watermark data candidates w(i)(i=1, 2, . . . ,n) are known, an image containing electronic watermark data is subjected to orthogonal transform to be converted into frequency components as f(1),f(2), . . . , F(n);

representing the values of elements corresponding to the frequency components containing the electronic watermark data in the frequency domain by F(1), F(2), . . . , F(n), the electronic watermark data W(i) is calculated and extracted on the basis of f(i) and F(i) according to the following equation;

2. An electronic watermark embedding device comprising.

detection means for detecting whether or not a first electronic watermark data is inserted into an input image in frequency-domain;

and

insertion means for inserting predetermined data into only a brightness signal of the input image;

wherein said insertion means has a selector for selecting a second electronic watermark data different from the first electronic watermark data in frequency-domain, when said detection means detects a fact that the first electronic watermark data is inserted into the input image, and for selecting a data of zero, when said detection means does not detect a fact that the first electronic watermark data is inserted into the input image, and

an adder for adding a data selected by said selector to the brightness signal.

3. The electronic watermark embedding device as claimed in claim 2,

wherein said detection means has means for converting the input image into image frequency components through discrete cosine transform, means for converting an original image into original frequency components through discrete cosine transform, means for subtracting the original frequency components from the image frequency components, and means for dividing a difference on the subtraction by the image frequency components.

4. The electronic watermark embedding device as claimed in claim 3, wherein said detection means has means for calculating an inner product between the result of the division and the first electronic watermark data, means for extracting a statistical similarity by the inner product, and means for deciding the fact that the first electronic watermark data is inserted into the input image, when the statistical similarity is greater than a predetermined value.