  The advent of the Internet led to the easy availability of digital data like
images, audio, and video. Easy access to multimedia gives rise to the issues
such as content authentication, security, copyright protection, and ownership
identification. Here, we discuss the concept of digital image watermarking with
a focus on the technique used in image watermark embedding and extraction of
the watermark. The detailed classification along with the basic
characteristics, namely visual imperceptibility, robustness, capacity, security
of digital watermarking is also presented in this work. Further, we have also
discussed the recent application areas of digital watermarking such as
healthcare, remote education, electronic voting systems, and the military. The
robustness is evaluated by examining the effect of image processing attacks on
the signed content and the watermark recoverability. The authors believe that
the comprehensive survey presented in this paper will help the new researchers
to gather knowledge in this domain. Further, the comparative analysis can
enkindle ideas to improve upon the already mentioned techniques.
