The watermarking of video that is to be transmitted in analog form is achieved by processing a digital version of the analog signal to add to each of at least some of the chrominance components that are part of a segment of a line of the video that is used to carry, at least in part, a bit of the additional data being impressed, the product of: a) a value of a periodically-varying, antipodal, waveform, b) a value that is representative of the bit of the additional watermark data being impressed; and c) optionally, a weighting value representative of the local business of the image at the point at which the additional watermark data is being added.
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