`  == Page issues ==  Alright, so.. this page suffers heavily from a number of issues, including direct quotation and single sourcing.  ``A simple example of a digital watermark would be a visible ``seal`` placed over an image to identify the copyright. However the watermark might contain additional information including the identity of the purchaser of a particular copy of the material. According to the human perception, the digital watermarks can be divided into two different types as follows: visible and invisible. Visible watermark is a secondary translucent overlaid into the primary image as shown in the figure.`` is taken from , page 4. The spacing here (you may need to edit this page) is identical to what would happen if you copied it directly from the PDF.  ``There are various spatial and frequency domain techniques used for adding watermarks to and removing them from signals. Purely spatial techniques are not robust to some attacks to the signal like cropping and zooming, whereas most frequency domain techniques and mixed-domain techniques are quite robust to such attacks.`` - This was stolen directly from , page 17. Kiranmayi Penumarthi is not quoted on this page.  ``Another application is to protect digital media by fingerprinting each copy with the purchaser's information.  If the purchaser makes illegitimate copies, these will contain his name.  Fingerprints are an extension to watermarking principle and can be both visible and invisible.`` is from , page 7.  I'm going to ask around for some help in how to solve this problem, as I don't quite have the time or effort to put into this. —  [  ·  ] `