Image Compression Based On Region Of Interest For Computerized Tomography Images

The use of computers for handling image data in the healthcare is growing. The amount of data produced by modem image generating techniques, such as Computed Tomography (CT) and Magnetic Resonance (MR), is vast. The amount of data might be a problem from a storage point of view or when the data is sent over a network. To overcome these problems data compression techniques adapted to these applications are needed. Many classes of images contain some spatial regions which are more important than other regions. Compression methods which are capable of achieving higher reconstruction quality of important parts of the image have been implemented. For medical images, only a small portion of the image might be diagnostically useful, but the cost of wrong interpretation is high. Algorithms which deliver lossless compression within the regions of interest (ROI), and lossy compression elsewhere in the image, might be the key to providing efficient and accurate image coding to the medical community. In this thesis both of compression techniques (lossy and lossless) of medical images using the JPEG algorithm (DCT), will be discussed

Video Encryption Based on Chaotic Systems in the Compression Domain

With the development of the internet and multimedia technology digital video encryption has attracted a great deal of research interest in the recent few years in applications. In this paper, we propose a method to encrypt video data. The proposed algorithm is based on the MPEG video coding standard. It selectively encrypts some DCT coefficients in the I frame, B frame and P frame in MPEG video compression by using chaotic systems. The key in this paper is chaotic sequence based on logistic mapping. It can produce the pseudo-random sequences with good randomness. The experimental results based on chaotic maps prove the effectiveness of the proposed method, showing advantages of large key space and high-level security. The proposed algorithm was measured through a series of tests and achieved good results. The results indicate that the algorithm can be implemented for video encryption efficiently and it provides considerable levels of security

A Secure and Robust Compressed Domain Video Steganography for Intra- and Inter-Frames Using Embedding-Based Byte Differencing (EBBD) Scheme.

This paper presents a novel secure and robust steganographic technique in the compressed video domain namely embedding-based byte differencing (EBBD). Unlike most of the current video steganographic techniques which take into account only the intra frames for data embedding, the proposed EBBD technique aims to hide information in both intra and inter frames. The information is embedded into a compressed video by simultaneously manipulating the quantized AC coefficients (AC-QTCs) of luminance components of the frames during MPEG-2 encoding process. Later, during the decoding process, the embedded information can be detected and extracted completely. Furthermore, the EBBD basically deals with two security concepts: data encryption and data concealing. Hence, during the embedding process, secret data is encrypted using the simplified data encryption standard (S-DES) algorithm to provide better security to the implemented system. The security of the method lies in selecting candidate AC-QTCs within each non-overlapping 8 × 8 sub-block using a pseudo random key. Basic performance of this steganographic technique verified through experiments on various existing MPEG-2 encoded videos over a wide range of embedded payload rates. Overall, the experimental results verify the excellent performance of the proposed EBBD with a better trade-off in terms of imperceptibility and payload, as compared with previous techniques while at the same time ensuring minimal bitrate increase and negligible degradation of PSNR values

PSNR quality predicted values for Y-components of intra and inter frames for six stego videos sequences.

<p>(a) I-frame, (b) B-frame and (c) P-frame.</p

Example of segmenting 8×8 coefficients data into a series of 2×2 blocks.

<p>Example of segmenting 8×8 coefficients data into a series of 2×2 blocks.</p

Summary of BER values of different steganographic techniques for compression attack.

<p>Summary of BER values of different steganographic techniques for compression attack.</p

Samples of SSIM quality map for Y-components of the I-frame within the 3^rd GOP of the stego MPEG-2 "Suzie" using different steganographic methods.

<p>(a) BPCS, (b) EBBD, (c) PVD, (d) EPVD and (e) TPVD.</p

Flowchart for data extraction in the compressed domain using EBBD steganographic scheme.

<p>Flowchart for data extraction in the compressed domain using EBBD steganographic scheme.</p

An example of selected 4x4 sub-block of AC- QTCs with embedded data.

<p>(a) Before embedding and (b) after embedding.</p