Very High Embedding Capacity Algorithm for Reversible Image Watermarking

Reversible image watermarking enables the embedding of copyright or useful information in a host image without any loss of information. Here a novel technique to improve the embedding capacity i.e. reversible watermarking using an adaptive prediction error expansion & pixel selection is proposed. This work is an improvement in conventional Prediction Error Expansion by adding two new techniques adaptive embedding & pixel selection. Instead of uniform embedding, here one or two bits of watermark are adaptively embed into the expandable pixels as per the regional complexity. Adaptive Prediction Error Expansion can obtain the embedded rate upto 1.3 bits per pixel as compared to the 1 BPP of conventional Prediction Error Expansion. Also an intermediate step of prediction error expansion is proposed to select relatively smooth pixels and ignore the rough ones. In other words, the rough pixels may remain unchanged, and only smooth pixels are expanded or shifted. Therefore compared with conventional Prediction Error Expansion, a more sharply distributed prediction error histogram is obtained i.e. , and a larger proportion of prediction-errors in the histogram are expanded to carry hidden data. So the amount of shifted pixels is diminished, which leads to a better image quality. With these improvements, this method performs better than conventional Prediction Error Expansion. It can embed larger payloads with less distortion (almost 30% greater than the conventional method). DOI: 10.17762/ijritcc2321-8169.150510

Pixel grouping of digital images for reversible data hiding

Pixel Grouping (PG) of digital images has been a key consideration in recent development of the Reversible Data Hiding (RDH) schemes. While a PG kernel with neighborhood pixels helps compute image groups for better embedding rate-distortion performance, only horizontal neighborhood pixel group of size 1×3 has so far been considered. In this paper, we formulate PG kernels of sizes 3×1, 2×3 and 3×2 and investigate their effect on the rate-distortion performance of a prominent PG-based RDH scheme. Specially, a kernel of size 3×2 (or 2×3) that creates a pair of pixel-trios having triangular shape and offers a greater possible correlation among the pixels. This kernel thus can be better utilized for improving a PG-based RDH scheme. Considering this, we develop and present an improved PG-based RDH scheme and the computational models of its key processes. Experimental results demonstrated that our proposed RDH scheme offers reasonably better  embedding rate-distortion performance than the original scheme

Reversible image watermarking based on a generalized integer transform

In this paper, a recently proposed reversible image watermarking algorithm based on reversible contrast mapping (RCM) is further developed. The integer transform, RCM, which is originally defined on a pair of integers, is extended to integer array of arbitrary length. Based on this generalization, the embedding capacity can be significantly increased. Meanwhile, the embedding distortion is well controlled by a suitable selection of embeddable pixel blocks. In fact, the hidden data is priorly embedded into the blocks that introduce less distortion. Furthermore, the proposed scheme does not need additional data compression, and it has low computational complexity. The experiments verify that the novel scheme outperforms the original RCM-based method and some state-of-the-art reversible watermarking algorithms, especially the ones based on integer transform.AcousticsComputer Science, Theory & MethodsEngineering, Electrical & ElectronicEICPCI-S(ISTP)