Of course, good steganography programs do not store information in sequential pieces of data, and instead use randomly chosen ones based on encryption schemes so to confuse cryptanalysis of images.

The modern manipulation of the bits of images is somewhat akin to the Cardano Grille of the classical steganography. The grille, a piece of paper with several small holes in it, when placed over passages of harmless text revealed secret messages in the words that were within the small holes. Similarly, the modern steganography tools imitate the grille method by only revealing the intelligible data when the right algorithim (a 'modernized' grille) is placed over the data.

And if you follow the anology of the grilles and audio/visual steganography, than you will understand why in the evolution of invisible ink, a small program named SNOW is the next step.

SNOW, written by Matthew Kwan, uses the 'Steganographic Nature of Whitespace' to hide secret messages. Using special algorithms which manipulate tabs and space marks, the program can convert a series of spaces into intelligible text. If you highlight the space below, you'll notice that there are several odd selections, even though you don't see anything. This was caused by several   tags in the HTML. When the SNOW programs reads these (along with a specified keyword), it outputs intelligbile text. Below, you can try the java applet version of the SNOW program (used with permission by the author).