Problems

Unfortunately, this particular implementation has problems. The algorithm used is very simple, making it very easy for a suspicious person to extract the hidden data. An algorithm that includes encryption would make it more difficult for the data to be extracted and decoded should the steganography be discovered.

The second shortcoming is the relatively small amount of data that can be stored using this file type and algorithm. By using only the low-order bits to store data, the amount of data that can be stored (in bytes) is the number of pixels divided by eight. In the example image (see Figure 1), which is 131 pixels wide and 200 pixels high, there is space for only about 3 kilobytes of data, or about 3700 7-bit ASCII characters. By using the two lowest-order bits, more data could be stored, but the change might become noticeable to the human eye.

Another problem is the lack of usefulness of the PGM format. It is an uncompressed image file type, and is very uncommonly used on the Internet and World Wide Web. A successful steganography program needs to use a common, unsuspicious file type such as JPEG, GIF, or PNG. For further development of this project, PNG is an excellent choice because it is not only lossless, but it has open-source code available for developers working with PNG[4].