A Survey on Improving Robustness of Image Watermarking By Using Gradient

Digital images can be captured easily with digital cameras, scanners and can be easily uploaded on the internet. Images can be appeared widely in the internet and can be copied from the internet. JPEG is one of the most popular image formats and can achieve high compression with high image quality. Information can be hidden into an image where the hidden information can be used or extracted for any particular purpose. Digital watermarking is a process to hide information in an image. Watermarks are visible but most of the watermarks are invisible. There are different types of invisible watermarks which can be used in different application such as fragile watermarks and robust watermarks. Fragile watermarks are designed and can be broken by simple image processing operations. We focus on geometrically robust watermarking and semi fragile water marking for digital images.