A new method of image watermarking in wavelet domain optimized by Firefly Algorithm is proposed to solve the problem that it is difficult to balance imperceptibility and robustness in watermarking.Firstly

the two layer Haar discrete wavelet transform (DWT) is applied on original host image

then singular value decomposition (SVD) is applied to the obtained second-level approximation subgraph LL

vertical detail subgraph LH and horizontal detail subgraph HL

which are taken as the watermark embedding position.Then

the watermarking image is processed by Arnold transform and one layer Haar DWT.The SVD is applied to the obtained approximation subgraph LL

vertical detail subgraph LH and horizontal detail subgraph HL

which are taken as the information to be embedded.Finally

the optimal intensity factor of watermarking embedding is obtained by using Firefly Algorithm (FA).The experimental results show that the proposed algorithm can well balance the imperceptibility and robustness of the image watermarking.