Watermarks based on the least significant bit(LSB) of the image data are very sensitive andfragile. Why?

Watermarks based on the least significant bit (LSB) of the image data are considered sensitive and fragile due to the following reasons:

1. Least Significant Bit (LSB) Encoding: This is the simplest way to embed information in an image. The idea is to replace the least significant bit in some pixels with a bit of the secret message. Because the LSB is the lowest bit, it holds the least value, hence changing it won't affect the pixel value much.

2. Sensitivity: The LSB watermarking method is sensitive because even a small change in the image can destroy the watermark. This is because the watermark is stored in the least significant bits of the image data. So, any image processing operation like cropping, rotating, contrast enhancement, or compression can easily alter or remove these bits, thereby destroying the watermark.

3. Fragility: The LSB watermarking method is fragile because it lacks robustness against attacks. Since the watermark is embedded in the least significant bits, it is not only easy to remove, but also easy to alter. An attacker can easily manipulate these bits to remove or alter the watermark without significantly degrading the quality of the image.

4. Lack of Redundancy: In LSB watermarking, the watermark is usually not repeated. This means that if a part of the image is altered or cropped, the corresponding part of the watermark will be lost. This lack of redundancy makes the watermark more fragile.

5. Visibility: Although changes to the LSB do not significantly affect the image quality, in some cases, they can still be noticeable. This can make the watermark more vulnerable to detection and removal.

In conclusion, while LSB watermarking is a simple and effective method for embedding information in an image, its sensitivity and fragility make it less suitable for applications where robustness and security are required.