“…The approach in (Langelaar, 2000) is effective but is lossy, too predictable and requires Huffman decoding of the JPEG file, while (Fridrich, 2004) is an adaption of (Langelaar, 2000) to JPEG. A fragile but lossless and file preserving watermarking algorithm is proposed in (Mobasseri, 2005) that is applicable to any entropy coded compression stream, provided that the total code space is not used. Inter-block correlation of the selected DCT coefficients for JPEG compressed data, by adding or subtracting an off-set to the mean value of the neighboring DCT coefficients, are also used in (Choi, 2000) and in (Luo, 2002) to embed watermark.…”