Multiple Watermarking Scheme for Digital Images

Abstract

If you hold any currency note up to the light you will see the portrait echoed in the note in form of watermark. It makes the currency note difficult to fake. Similarly the boom of internet which has acted as a distribution system for digital media, content owner sees the risk of piracy. Invisible watermarking involves imperceptibly embedding data called as “Watermark” into an image or other digital media to protect its value. Different techniques are used to embed different types of watermark to accomplish various goals. Some are intended to robustly carry ownership information, some are intended to carry content verification information like in medical imaging. These two are extremely diverse requirements. In this work, to accomplish several goals we propose to embed multiple watermarks in a cover image. A robust watermark is embedded to convey the ownership information. For it to be effective, it should robustly resist image processing attacks, intentional or unintentional, that might remove it. For the application of content authentication of image we focus on how the watermark can be used to assist in verifying the integrity of the associated cover image. We call this watermark a “Fragile Water mark” as it is extremely sensitive to any intentional or unintentional change.