Digital image forgery is the process of changing contents of a document and representing the changes as true copies of the original. Due to the availability of powerful image processing and editing softwares, it is easy to manipulate and edit digital images. Authenticity of an image received on communication channel is important now a day as digital images are accepted as evidence into court of law. This paper includes active and passive approaches used for finding forged image. These approaches cover three techniques such as watermarking, hashing and jpeg compression to find manipulated image.