Mathematical Abstract of a DCT-QIM Watermarking System with RS Coding and Soft Beam Decoding

Abstract

This note gives a concise mathematical description of a watermarking pipeline that embedsa short payload into the mid-frequency DCT coefficients of image blocks using QuantizationIndex Modulation (QIM), protects the payload with Reed–Solomon (RS) channel codingover GF(28), and recovers candidates via soft symbol scoring and a byte-level beam search.A case-insensitive normalized Levenshtein similarity is used to report a match percentagebetween a user-supplied ideal string and the recovered candidate; this percentage provides arobust, interpretable indicator of correspondence even when bit-level integrity checks fail orthe file has been heavily modified.