This is a feature request for a hidden watermark tool in the BQM, so that we can conceal a hidden plain-text or image watermark into our photos. I am aware of a wavelet-based method and a fourier-based one. http://www.cs.cornell.edu/topiwala/wavelets/report.html You can do this using Mathmap or G'MIC, however those tools do not work in batch. It would be awesome if digiKam let us do this! Reproducible: Always
G'MIC's "Fourier watermark" can be found in the "Spectral filters" menu: https://gmicol.greyc.fr/ A discussion about it: https://www.flickr.com/groups/gmic/discuss/72157624462331405/
G'MIC Reference: http://gmic.sourceforge.net/reference.shtml#watermark_fourier
Note : GMicQt is not yet available in BQM. It's only present in Image Editor. Gilles Caulier