Integrated encoding with high efficiency for digital steganography

Embedding in Two Least Significant Bits with Wet Paper Coding

“…In fact, the choice of addition or subtraction will be determined in the second layer embedding. So another steganographic method called "double-layered embedding" (DLE) was proposed [14][15][16]. It shows that the second LSB plane could be used to accommodate additional secret data by selecting suitable operations of addition/subtraction.…”