TL;DR: The image coding results, calculated from actual file sizes and images reconstructed by the decoding algorithm, are either comparable to or surpass previous results obtained through much more sophisticated and computationally complex methods.
Abstract: Embedded zerotree wavelet (EZW) coding, introduced by Shapiro (see IEEE Trans. Signal Processing, vol.41, no.12, p.3445, 1993), is a very effective and computationally simple technique for image compression. We offer an alternative explanation of the principles of its operation, so that the reasons for its excellent performance can be better understood. These principles are partial ordering by magnitude with a set partitioning sorting algorithm, ordered bit plane transmission, and exploitation of self-similarity across different scales of an image wavelet transform. Moreover, we present a new and different implementation based on set partitioning in hierarchical trees (SPIHT), which provides even better performance than our previously reported extension of EZW that surpassed the performance of the original EZW. The image coding results, calculated from actual file sizes and images reconstructed by the decoding algorithm, are either comparable to or surpass previous results obtained through much more sophisticated and computationally complex methods. In addition, the new coding and decoding procedures are extremely fast, and they can be made even faster, with only small loss in performance, by omitting entropy coding of the bit stream by the arithmetic code.
TL;DR: The paper discusses the feasibility of coding an "undetectable" digital water mark on a standard 512/spl times/512 intensity image with an 8 bit gray scale, capable of carrying such information as authentication or authorisation codes, or a legend essential for image interpretation.
Abstract: The paper discusses the feasibility of coding an "undetectable" digital water mark on a standard 512/spl times/512 intensity image with an 8 bit gray scale. The watermark is capable of carrying such information as authentication or authorisation codes, or a legend essential for image interpretation. This capability is envisaged to find application in image tagging, copyright enforcement, counterfeit protection, and controlled access. Two methods of implementation are discussed. The first is based on bit plane manipulation of the LSB, which offers easy and rapid decoding. The second method utilises linear addition of the water mark to the image data, and is more difficult to decode, offering inherent security. This linearity property also allows some image processing, such as averaging, to take place on the image, without corrupting the water mark beyond recovery. Either method is potentially compatible with JPEG and MPEG processing. >
TL;DR: This paper introduces high-rate uncorrelated bit extraction (HRUBE), a framework for interpolating, transforming for decorrelation, and encoding channel measurements using a multibit adaptive quantization scheme which allows multiple bits per component.
Abstract: Secret keys can be generated and shared between two wireless nodes by measuring and encoding radio channel characteristics without ever revealing the secret key to an eavesdropper at a third location. This paper addresses bit extraction, i.e., the extraction of secret key bits from noisy radio channel measurements at two nodes such that the two secret keys reliably agree. Problems include 1) nonsimultaneous directional measurements, 2) correlated bit streams, and 3) low bit rate of secret key generation. This paper introduces high-rate uncorrelated bit extraction (HRUBE), a framework for interpolating, transforming for decorrelation, and encoding channel measurements using a multibit adaptive quantization scheme which allows multiple bits per component. We present an analysis of the probability of bit disagreement in generated secret keys, and we use experimental data to demonstrate the HRUBE scheme and to quantify its experimental performance. As two examples, the implemented HRUBE system can achieve 22 bits per second at a bit disagreement rate of 2.2 percent, or 10 bits per second at a bit disagreement rate of 0.54 percent.
TL;DR: In this article, a multi-code code division multiple access system allows a user at a radio transmitter unit to dynamically change its source data bit rate by selecting one of the plurality of source bit rates, an adjustable coding means in the transmitter spreads and transmits the user's digital bit stream received at the selected bit rate to a channel bit rate which at least equals the highest bit rate of said plurality of bit rates.
Abstract: A multi-code code division multiple access system allows a user at a radio transmitter unit to dynamically change its source data bit rate. In response to a user input selecting one of said plurality of source bit rates, an adjustable coding means in the transmitter spreads and transmits the user's digital bit stream received at the selected bit rate to a channel bit rate which at least equals the highest bit rate of said plurality of source bit rates. The plurality of source bit rates includes a basic bit rate R and at least one bit rate which is a multiple M of the basic bit rate R, where M is an integer of at least 1. The user's input selects a particular user source bit rate by identifying a basic bit rate multiple M to a base station that is to receive the transmission.
TL;DR: Experimental results indicate that the proposed digital image stabilizer is a computationally efficient alternative to existing DIS systems.
Abstract: A fast digital image stabilizer based on the Gray-coded bit-plane matching is proposed which is robust to irregular conditions such as moving objects and intentional panning. The proposed digital image stabilization (DIS) system performs motion estimation using the Gray-coded bit-plane of video sequences, greatly reducing the computational load. This motion estimation method can be realized using only binary Boolean functions which have significantly reduced computational complexity, while the accuracy of motion estimation is maintained. In order to further improve the computational efficiency, the Gray-coded bit-plane matching with the three-step search (3SS) is proposed. Experimental results indicate that the proposed digital image stabilizer is a computationally efficient alternative to existing DIS systems.