Digital image embedding, extraction method and device

• Main Authors: LI XIAOLONG, CHENG DAOFANG, QI WENFA, YANG BIN
• Format: Patent
• Language: Chinese; English
• Published: 13.04.2011
• Subjects: CALCULATING; COMPUTING; COUNTING; IMAGE DATA PROCESSING OR GENERATION, IN GENERAL; PHYSICS

The invention discloses a method of embedding watermark to a digital image. In order to solve the problem of prior art that the technology can not resist printing or scanning attacks, the intermediate and low frequency coefficients in image blocking DCT transform are firstly grouped, the coefficients in each group are divided into two parts with the same number, and the watermark signal is embedded into the first part and the second part of the low frequency coefficients in each transform domain. So the robustness is very strong. The invention also discloses a method of extracting watermark from a digital image. For watermark extracting, the coefficients are grouped in a same method with the watermark embedding process, the intermediate and low frequency coefficients in each group are divided into two parts with the same number, the difference of the square sum of the intermediate and low frequency coefficients in the two parts of the transform domain is calculated to acquire the watermark signal. The inventi