Question

which of the following methods are used for digital watermarking?
a. implanted subroutines that link to a central web server automatically when the watermarked file is accessed
b. invisible modification of the lsbs in the file
c. layering visible symbols on top of the image
d. using a hex editor to alter the image data

Explanation:

Digital watermarking often uses techniques that embed data invisibly or visibly in digital media. LSB (Least Significant Bit) modification is a standard invisible digital watermarking method, as altering the least significant bits of file data does not noticeably change the media while embedding a watermark. Option a describes a remote tracking method, not watermarking. Option c is a visible overlay, not a typical watermarking implementation. Option d is a general data editing tool, not a specific watermarking method.

Answer:

b. Invisible modification of the LSBs in the file