Satellite enhanced image watermarking using gradient direction quantization

We proposed a simple and dynamic wavelet-based algorithm for enhancement of the satellite image sharpness or blurriness of a satellite image. Four set of methods are followed here (Denoising, Decomposing, Sharpness Estimation and Filtering). First Denoising is done on the input images and then it operates by initially decomposing the input image through a multilevel separable DWT. After this, the log-energies of the DWT sub bands are computed. A Scalar Index corresponding to the input image´s sharpness is computed through the weighted average of the computed log-energies. Along with the Scalar Sharpness Index, a Block based algorithm is presented to determining the local perceived sharpness. This method is the simplest, fastest and accurate comparing to the currently best-performing techniques for the sharpness estimation. In this Paper A robust quantization-based image watermarking scheme, called the gradient direction watermarking (GDWM) is introduced for satellite enhanced image watermarking. In GDWM, the watermark bits are embedded by quantizing the angles of significant gradient vectors at multiple wavelet scales. To quantize the gradient direction, the DWT coefficients are modified based on the derived relationship between changes in the coefficients and the change in the gradient direction. This Watermarking technique is more robust for various sizes of watermark image. When compared to the existing watermarking techniques the proposed enhanced watermarking technique shows best results.