Crypto - from the Greek 'Kryptos' meaning hidden
These cryptographic drawings and engravings include both hidden animals and multiple hidden titles expressed in Caesar code, Morse code, and other systems. Hidden animals are drawn using branches, negative space, the contours of hillsides, and other pieces of the landscape set at varying depths in the space of the picture. To see them the viewer must look in a different way than when viewing the more conventionally drawn figures that occupy the picture space (and sometimes serve to misdirect the eye). The number of hidden figures is often used as an encryption key for the hidden titles.
Many of the hidden titles are written using landscape elements to express 5-bit binary numbers. For example, a five leaf plant with leaves pointed up or down can be read as a number if you take an upward pointing leaf as a 1 and a downward pointing leaf as a 0. If the pattern is up, down, up, down, down then that is 10100 in binary... a 5. (I always construct my binary numbers backwards with the least significant bit as the leftmost or topmost bit depending on orientation. Of course, if you don't know this then you can't read my code properly. In my system 10100=5.) The fifth letter is E. That plant represents an E.
The hidden figures and titles carry additional layers of meaning and require the viewer to see the picture in more than one way simultaneously.