サブバンド処理を用いた画像電子透かし

Abstract

This paper describes digital watermarking methods using sub-band image processing. A bi-level (1 bit/pixel) watermarking image has been embedded in target gray scale images. 1-stage and 2-stage sub-band processing methods have been employed. In the 1-stage sub-band, a target image is decomposed into LL, LH, HL and HH sub-band images, and watermarking information 1/0 is embedded in these LH, HL or HH sub-band images. In the 2-stage sub-band, the LL sub-band image is further decomposed into LL2, LH2, HL2 and HH2 sub-band images, and the watermarking information is also embedded in the LH2, HL2 or HH2 sub-band images. For processing each sub-band image, two embedding methods have been deployed. Pixel values of sub-band images are modified by the watermarking information 1/0. The experiments of these watermarking methods have been carried out. It is our findings that how much and what aspects of embedded image quality and watermark recovery accuracy relate to watermark embedding strength and watermark attacks.