By: SK GOLAM ROCKY BUL ECE13422

Digital watermarking is the process of embedding information into a digital signal which may be used to identify its owner,in the same manner as paper bearing watermark for visible identification.

Mainly it is used for copyright protection of digital media.Currently the unauthorized distribution of digital audio & video over the internet is the big problem.In this scenario,digital watermarking may be useful to setup controlled audio distribution & to provide efficient means for copyright protection.

Invisible/Inaudible Information is embedded without digital content

degradation, because of the level of embedding operation is too small for human to notice the change.

Inseparable The embedded information can survive after some

processing, compression and format transformation.

Unchanging data file size Data size of the media is not changed before and

after embedding operation because information is embedded directly into the media.

Perform 2D-DWT to divide image into LL, HL, LH and HH sub-bands.

Select coefficients from the LL, HL, LH and HH sub-bands that exceed a particular threshold T1

Embed watermarking data via additive modification

t’i = ti + α|ti|xi xi = watermark α = weighting constant

Perform 2D-IDWT to create “watermarked image”

According to Human Perception Visible Invisible

According to Robustness Fragile Semi fragile Robust

According to Document Text Image

Logo or seal of the organization which holds the rights to the primary image, it allows the primary image to be viewed, but still visible it clearly as the property of the owning organization.

Overlay the watermark in such a way that makes it difficult to remove, if the goal of indicating property rights is to be achieved.

WatermarkImage with watermark

Embedding level is too small to notice Can be retrieved by extraction software Applications:

Authentication Copyrighting Etc…

A watermark is called fragile if it fails to be detected after the slightest modification.

A watermark is called semi-fragile if it resists beginning transformations but fails detection after malignant transformations.

A watermark is called robust if it resists a designated class of transformations.

Text/Image/Audio watermarking refers to embedding watermarks in an text/image/audio in order to protect the image from illegal copying and identify manipulation.

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