This program hides GIF images within Web pages by changing the picture from a recognizable image into a solid color. The creator, Robert Wallingford, describes it this way:
When I first conceived the system, this was a black rectangle. Then I saw that I could make this rectangle any of 16 million colors. Now you must be asking why anyone would want to make a picture that is all one color. If this were an irreversible process, it would be completely useless. However, if you can easily restore the original picture, there are many useful applications on the Internet. Some of these applications may even be legal.
Most of us have at least one graphic file that we don't want everyone to see. We can now use mask.com to make it a single color such as black. Then, in the HTML language used in Web page design, instead of using a background color we can use this "masked" graphic. The HTML language will even automatically replicate this hidden image to fill the desired area.
On the receiving end, selected users know that the background contains a hidden picture. They can "save background image" with their right mouse button. They can then use fixx.com to restore the original image. Others who do not know about this system will not even be aware that the image exists.