Reversible Data Hiding with a New Local Contrast Enhancement Approach

Abstract

Reversible data hiding schemes hide information into a digital image and simultaneously increase its contrast. The improvements of the different approaches aim to increase the capacity, contrast, and quality of the image. However, recent proposals contrast the image globally and lose local details since they use two common methodologies that may not contribute to obtaining better results. Firstly, to generate vacancies for hiding information, most schemes start with a preprocessing applied to the histogram that may introduce visual distortions and set the maximum hiding rate in advance. Secondly, just a few hiding ranges are selected in the histogram, which means that just limited contrast and capacity may be achieved. To solve these problems, in this paper, a novel approach without preprocessing performs an automatic selection of multiple hiding ranges into the histograms. The selection stage is based on an optimization process, and the iterative-based algorithm increases capacity at embedding execution. Results show that quality and capacity values overcome previous approaches. Additionally, visual results show how greyscale values are better differentiated in the image, revealing details globally and locally.

Selectivity Estimation of Inequality Joins in Databases

“…Histograms, as a form of synopsis-based methods, have been extensively studied [6,8] and are widely adopted in common database systems [14] for the purpose of selectivity estimation, including MySQL, PostgreSQL, Oracle, and SQL-Server [15][16][17][18]. Histograms are commonly used in databases for other tasks, including, for instance, data security and watermarking [19,20].…”

Efficient Reversible Data Hiding Based on Connected Component Construction and Prediction Error Adjustment

“…This has motivated researchers to study reversible information hiding (RIH) [11] or say reversible data hiding (RDH) [12], reversible watermarking [13] to ensure that both the secret message and the original cover media can be reconstructed at the receiver side. Many RDH algorithms can be found in the literature such as [13][14][15][16][17][18][19][20].…”