{'fraction_non_alphanumeric': 0.0218303946263644, 'fraction_numerical': 0.0025188916876574307, 'mean_word_length': 5.306878306878307, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Digital Copyright Protection for Multimedia Documents

Copyright infringements of digital audio, images, videos, and 3D models can be detected by means of digital watermarks. Digital watermarks are invisible signatures that are embedded in a document in such a way that they are resistant to unintentional or malicious modifications of the document: only the copyright holder owns the key that permits the decoding and/or removal of the watermark. This watermark, typically a 64 bit information string that is registered at the copyright certificate center, allows to uniquely identify the document and its owner. The DCT watermarking process relies on the inability of the human visual system to perceive small differences in optical data, especially in edge areas. The watermark bits, first encoded as a pseudo-random sequence, are then hidden in image parts where the color or gray values vary rapidly. The illustrations below show from left to right an original image, the content dependent and pseudo-random sequence based pseudorandom pattern (watermark), and the resulting protected image (original image combined with the pseudo-random pattern); the image quality is fully preserved.