Steganography

Dec 7, 2022#fun109

AI Translation

This post is translated from Chinese into English through AI.View Original

AI-generated summary

The text discusses the concept of steganography, which involves hiding messages within images. It explains how the technique works by modifying the least significant bit of each pixel's blue value. The human eye cannot easily detect these changes, allowing for the hiding of information in the image. The text emphasizes that this technique is possible because the human eye cannot easily distinguish the last 4 bits of an RGB channel's data.

In this project, images are used as examples. First, a coding format for images, ppm, is introduced:

The first line indicates the format of the ppm file.
The second line indicates the width and height.
The third line indicates the color range.
The following lines represent the RGB values of each pixel.

P3
2 2
255
 29  83  36      45  64  57   
188 229 201     123 162 184

This is how it is explained:

We will explore a method of hiding messages. Although most images have 8-bit data for each RGB channel, the human eye cannot easily perceive the differences in the last 4 bits. Therefore, we can hide information in the least significant bit of each pixel's blue value. If the last bit is 0, the entire pixel is converted to black (255,255,255). If the last bit is 1, it is converted to white (0,0,0).

The key is: each RGB channel has 8-bit data, but the human eye cannot easily perceive the differences in the last 4 bits, which gives us room for manipulation.