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I have an idea of applying DCT on an image and then embed text into the LSB of the coefficient of DCT and transmit the image to B (the receiver). Now, using the same procedure, can B transmit another watermark along with the previous one with this method to another person? Is this a suitable procedure?

  • I'd say no, unless A and B had some rules so they wouldn't write over each others information. maybe they would agree that odd bits would be used by A and even bits by B. But this halves your secret bit rate, and the bit rate of a hidden message using the LSB of a DCT is pretty small already I'm guessing. – daniel Apr 11 '17 at 11:24
  • @daniel There are algorithms that can provide error correction and detection with arbitrary precision (e.g. reed-solomon codes), which could provide resilience against a given number of bits being corrupted by another party. – forest Feb 21 '18 at 6:34
  • @Sana Is this suitable for what? Yes, it would work in that you could embed information in a (lossless) image, but what is the purpose? No one can answer you as to whether or not it is a suitable procedure if no one knows what it is necessary for. – forest Feb 21 '18 at 6:36
  • @forest what do you mean? What happens if you have 1 message of 100 bits, and a nose source of any given number (up to 100 bits) en.m.wikipedia.org/wiki/Channel_capacity – daniel Feb 21 '18 at 7:01
  • @daniel Obviously error correction codes expand the amount of data required to hold a given message. The method of transmission is irrelevant. All that matters is that an (ECC-protected) message of a given length is able to withstand the corruption of an arbitrary number of bits (no bits are more important than any others). – forest Feb 21 '18 at 7:26
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Since you usually compress images, which would do something very similar, at least in the case of jpeg compression, but would completely omit or severely reduce LSBs, I guess, no, in practice not.

If you're sending around full-color pictures uncompressed, at least I'd look at the entropy of your LSBs and the PSD, and the latter would probably lead to the suspicion that you're using steganography.

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