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algorithmwatermark

Is there any innovative watermarking technique that doesn't make the watermark obvious?

Is there a watermarking technique which doesn't make the watermark obvious yet by analyzing the image you can identify the source?

Solution

  • Yes, it's called "robust" digital watermarking (of images). A robust digital watermark should be recognizable even when you compress, resize, crop or translate the image. Because you can't embed robust digital watermarks into lowest-order bits, say (as they get lost in compression), the process is typically

    1. transform the image to an alternative space, e.g. using discrete cosine transform
    2. embed the watermark in the transformed space
    3. transform the compound result back to the original space, e.g. reverse discrete cosine transform

    BTW in order to make the watermark non-obvious but recognizable, you just need to make sure that the watermark in itself is random so that you can't immediately recognize it even if you carry out the watermark extraction procedure if you don't know that the watermark should be.