The trade off between the watermarking requirements can mark the effectiveness of each approach.The relative importance of each requirement is somewhat application dependent. Several of the requirement may b correlated whereby an improvement in one requirement may somewhat lead to the deterioration or improvement of the other. In copyright protection the need to retrieve watermark (independent from the image) focus on robustness among the requirement for this application,but in authentication the criteria changes as the goal is to discriminate between malicious and non-malicious attacks and localization of tampered area.