This is another one of those topics that can get fairly technical, but I think you all need to have some understanding of this issue as it is going to become more significant in the near future. The subject is storing of information in images, rather than using text. The technical term for storing coded or secret information in images is "steganography". What does this mean? You first need to understand the difference between text and images, and how the human brain differs from a computer in processing these.
The term "text" in computers generally means the representation of letters, numbers, and punctuation as numeric codes. The codes are small and compact - you need only 8 or 16 bits (one or two bytes) to store or represent a single alphabet letter in a computer. So when you receive a text email, it really is just a succession of these numeric codes. When it comes to showing the letter on the screen or a printed page, Windows takes that numeric code and looks up that code in a font file, which then tells Windows how to actually display the shape of, for example, an 'A' in the Arial font. The important thing is that the computer instantly knows that the code for an 'A' represents the letter 'A'.
Images (i.e. pictures) are processed quite differently, and this points up one of the major differences between the human brain and a computer. Our brains are very adept at image processing and can look at the image of an 'A' on the screen and just about instantaneously know it is an 'A', even if it is in a font that you have never seen before. For a computer to take an image of an 'A' and figure out that it is in fact an 'A' and that in fact it is shown in the Arial font takes quite a bit of processing - the term in this case is "optical character recognition" - still an inexact science. This is also why computer handwriting recognition is still so inaccurate - the computer just can't recognize easily your particular scrawl as the letter 'A'.
Another example: suppose we took an image of the Mona Lisa and altered her enigmatic smile to a frown. If I showed that image to you, you would almost instantaneously recognize that it is the Mona Lisa, and pretty quickly thereafter you would notice that something wasn't quite right, and that the something was that she was frowning. For a computer to arrive at that knowledge would take some very intense processing.
The point here is that it is very difficult for a computer to recognize information in an image, and the bad guys out there have started to latch on to this fact. They have realized that spam filter programs for text email are getting pretty adept at finding their junk and are looking for new ways to defeat the filters. So the next wave of spam will use images to carry the message and thus defeat the spam filtering programs. If you receive one of these emails the image itself may actually look like normal computer text, so you may be easy to be fooled.
I can't give you any more definitive data on this right now, but the word on the street is that spam email using steganographic techniques will begin to steadily increase soon. We had been basking in the light of fairly good spam email filtering for a while now, but the next battle in this war is just beginning.
By the way, you may have run across another form of steganography if you have gone to some websites that require you to register with them. In order to eliminate automated computer programs (bots) from create logons to their service, they show you an image of a password and ask you to type it back. Easy for you, almost impossible for a robot program.
(Bob Seidel is a local computer consultant in the Southport - Oak Island area. You can visit his Website at www.bobseidel.com or e-mail questions or column ideas to him at bsc@bobseidel.com. For specific inquiries, please call Bob Seidel Consulting, LLC at 278-1007.)