What is the role of the IDAT data chunk in PNG LSB steganography, and how is it compressed?

The IDAT data chunk stores the actual pixel data of the PNG image. It uses a compression algorithm based on LZ77 (deflate), and the compressed data can be decompressed using zlib. In LSB steganography, the payload is hidden by altering the least significant bits of the decompressed pixel data before re-compressing it into the IDAT chunk. Tools like cloacked-pixel replace all other chunks with only the essential IDAT chunk.