06-03-2012, 03:22 PM
Digital Watermarking
[attachment=18029]
Introduction
1More information is transmitted in a digital format now than ever, and the growth in this trend will not plateau in the foreseeable future. Digital information is susceptible to having copies made at the same quality as the original.
There are many types of digital information and data. The types concentrated on in this report are:
• Digital Images
• Digital Audio, and
• Digital Videos
A watermark is 2A pattern of bits inserted into a digital image, audio or video file that identifies the file's copyright information (author, rights, etc.). The name “watermark” is derived from the faintly visible marks imprinted on organisational stationery.
Unlike printed watermarks, which are intended to be somewhat visible (like the very light compass stamp watermarking this report), digital watermarks are designed to be completely invisible, or in the case of audio clips, inaudible.
Technical Details
Digital watermarking technology makes use of the fact that the human eye has only a limited ability to observe differences. Minor modifications in the colour values of an image are subconsciously corrected by the eye, so that the observer does not notice any difference.
While vendors of digital watermarking schemes do not publicly release the exact methods used to create their watermarks, they do admit to using the following basic procedure (with obvious variations and additions by each vendor).
Images
These are some of the methods that can be used to test whether a watermark can survive different changes to the image it is embedded in.
Compare this Original Image with the attacked images below, and see if you can spot any changes in quality.
[attachment=18029]
Introduction
1More information is transmitted in a digital format now than ever, and the growth in this trend will not plateau in the foreseeable future. Digital information is susceptible to having copies made at the same quality as the original.
There are many types of digital information and data. The types concentrated on in this report are:
• Digital Images
• Digital Audio, and
• Digital Videos
A watermark is 2A pattern of bits inserted into a digital image, audio or video file that identifies the file's copyright information (author, rights, etc.). The name “watermark” is derived from the faintly visible marks imprinted on organisational stationery.
Unlike printed watermarks, which are intended to be somewhat visible (like the very light compass stamp watermarking this report), digital watermarks are designed to be completely invisible, or in the case of audio clips, inaudible.
Technical Details
Digital watermarking technology makes use of the fact that the human eye has only a limited ability to observe differences. Minor modifications in the colour values of an image are subconsciously corrected by the eye, so that the observer does not notice any difference.
While vendors of digital watermarking schemes do not publicly release the exact methods used to create their watermarks, they do admit to using the following basic procedure (with obvious variations and additions by each vendor).
Images
These are some of the methods that can be used to test whether a watermark can survive different changes to the image it is embedded in.
Compare this Original Image with the attacked images below, and see if you can spot any changes in quality.
