Steganography is a technique of hiding message, file within another file.

This tool allows to encrypt a message inside an image. The idea behind it is that every image is a matrix of pixels.
Each pixel is represented by 3 values: Red Green Blue (RGB) which can take the value range 0-255.
Each ASCII character can be presented in binary form. For example: X -> 88 -> 1011000.

For every '1' in binary message we change 0-255 RGB value to even and for '0' to odd.
After each binary sequence of a character there is a bit that indicates the end of message: '0' - message end; '1' - message continue

Each character with message end indicator is stored on 3 pixels (3 pixel x 3 RGB values = 9 bits).

Text to encrypt: XY
Binary representation: 01011000 01011001
Binary with message end indicators: 010110001010110010
Image pixels: (100,230,93) (213,210,212) (141,53,53) (31,0,34) (99,90,211) (43,45,61)
Bit encryption:

010
(100,230,93)
Encrypted: (100,231,92)