2000-332988 is referenced by 24 patents.

PROBLEM TO BE SOLVED: To provide a digital information embedding and extracting device and a method whose image deterioration due to embedding is small and which have high adaptability to the existing MPEG(moving picture expert group)/JPEG(joint photographic expert group) compression. SOLUTION: A block dividing part 11 divides an image signal 71 into plural blocks according to a prescribed size. A frequency converting part 12 performs frequency conversion of each block and respectively calculates frequency coefficients. A coefficient calculating part 13 selects a specific frequency coefficient string Ca for each block and calculates respective absolute average values M and energy S. A quantizing part 14 performs linear quantization of M by using a prescribed quantization step size Q to calculate a quantization value (q) in the case S is equal to or more than a prescribed threshold K. A signal substituting part 15 substitutes (q) with the value (q') on the basis of (q) and the value of digital information to be embedded. A coefficient correcting part 16 perform inverse-linear quantization of (q') by using Q, calculates an average value M', calculates the difference DM between M' and M and corrects Ca. A frequency inverse converting part 17 reconstructs an image signal 72 due to frequency inverse conversion.

Title
Device and method for embedding and extracting digital information and medium with program for executing the method recorded thereon
Application Number
11-138914
Publication Number
2000-332988
Application Date
May 19, 1999
Publication Date
November 30, 2000
Inventor
Katsura Takuji
Inoue Takashi
Assignee
Matsushita Electric
IPC
G09C 05/00
G06T 01/00
H04N 01/387