Very Fast Watermarking by Reversible Contrast Mapping

Abstract

Reversible contrast mapping (RCM) is a simple integer transform that applies to pairs of pixels. For some pairs of pixels, RCM is invertible, even if the least significant bits (LSBs) of the transformed pixels are lost. The data space occupied by the LSBs is suitable for data hiding. The embedded information bit-rates of the proposed spatial domain reversible watermarking scheme are close to the highest bit-rates reported so far. The scheme does not need additional data compression, and, in terms of mathematical complexity, it appears to be the lowest complexity one proposed up to now. A very fast lookup table implementation is proposed. Robustness against cropping can be ensured as well.Index Terms-Difference expansion, embedding bit-rate, reversible contrast mapping (RCM), reversible watermarking.

Một Lược Đồ Thủy Vân Thuận Nghịch Khóa Công Khai Cho Cơ Sở Dữ Liệu Dựa Trên Kỹ Thuật Mở Rộng Các Thuộc Tính Kiểu Thực

“…Thủy vân dễ vỡ [2][3][4][5][6][7][8][9][10][11][12] yêu cầu dấu thủy vân phải nhạy cảm (dễ vỡ) trƣớc những sự tấn công trái phép trên dữ liệu thủy vân, dù chỉ vài bít. Do đó các lƣợc đồ này thƣờng đƣợc dùng trong việc phòng chống giả mạo, hay xác thực tính toàn vẹn của dữ liệu thủy vân.…”

Secret Image Transmission Through Mosaic Image

“…Embed the bit streams with reversible contrast mapping [14] 10. Construct the bit stream I including 1) number of iterations for embedding;2) the number of pixel pairs in the last iteration; 3)The Huffman Table constructed above.…”

“…But this makes the attraction of the eavesdroppers while in the transmission. An alternative is used for avoiding this problem that is data hiding [8] [14]. In these types of approach a cover image is used for hiding the secret data.…”

Fidelity Analysis of Additive and Multiplicative Watermarked Images in Integrated Domain

“…In spatial domain, watermark is directly embedded into the image pixels by altering the intensity values of the pixels. Least Significant Bit (LSB) substitution [12], changing paired pixels [13], [4], coding by textured blocks [14], additive approach [21], simple integer transform using reversible contrast mapping [8], dual watermarking techniques [18] are spatial domain watermarking techniques. In frequency domain watermarking, the spatial image is transformed into frequency coefficients using transforms like Discrete Fourier Transform (DFT), Discrete Cosine Transform (DCT), and Discrete Wavelet Transform (DWT) and watermark is embedded into transformed coefficients.…”