What is Watermarking
What is a watermark?
Originally a watermark is a more or less transparent image or text that has been applied to a piece of paper, another image to either protect the original image, or to make it harder to copy the item e.g. money watermarks or stamp watermarks.
What is a digital watermark?
A digital watermark added to a photo, is a more or less visible information in the form of a text or some other photo/image that ha been added to the original photo. The added information can be more or less transparent to make it either easy or hard to notice the watermark.
Why is it called a watermark?
The origin of the water part of a watermark can be found back when a watermark was something that only existed in paper, at that time the watermark was created by changing the thickness of the paper and thereby creating a shadow/lightness in the watermarked paper. This was done while the paper was still wet/watery and therefore the mark created by this process is called a watermark.
How is a watermark added to a digital image?
A transparent watermark is added to a photo by changing the image on the pixel level (a pixel is one dot of the image). The pixels that will make up the resulting watermark is changed more or less in the direction of the watermarking image, if e.g. the watermark is 50% transparent, 50% of the RGB (Red, Green & Blue) values are deducted from the original image, and 50% of the RGB values from the watermark are added to the image.
Why add a watermark to a digital photography?
When adding a watermark to a photo you send a clear signal that this photo should not be copied/used without your consent. Also if you add both a highly visible watermark and a almost hidden, it will be much more easy for the thief to overlook the invisible and thereby adding more protection of your photos!
How about adding an invisible digital watermark to my photos (Steganography watermark)?
There is done a lot of research into adding an invisible watermark to images that is hard to remove again, but sadly many of these programs do not work on jpeg images since these are transformed in the compression of the image. TSR Soft is working on the option of adding a hidden watermark to the image and this option will be released in a later version.