A Survey on Digital Image Watermarking Based on DCT and NPA

A digital image watermarking technique has been as a possible declaration to the necessity of modifying, copyright protection and authentication of transmission data in an exceedingly much networked setting, it makes possible to identify the author, owner, approved client of document victimization Discrete Cosine Transformation technique were developed in recent years. As a results of it's going to recover the watermarked data back to the first host image reversible watermarking algorithms are appropriate for military, medical and completely different fields. We proposed a new propose algorithm (NPA) supported reversible bit replacement technique in watermarking rule supported bit replacement methodology. It will entirely recover the first data to a high extent, however even have strong robust and hard quality and recover time also minimum as compare to DCT The watermark is superimposed in choose coefficients with necessary image energy at intervals the transform domain. Benefits of the technique improved resistance to attacks on the watermark, hidden visual masking utilizing the time-frequency localization property of transform domain. Digital image watermarking that doesn't want the first image for watermark detection and purpose reversible technique is strong robust and provide ownership, protection.