3189198
Man-made structure detection in natural images using a causal multiscale random field
This paper presents a generative model based approach to man-made structure detection in 2D (two-dimensional) natural images. The proposed approach uses a causal multiscale random field suggested by Bouman and Shapiro (1994) as a prior model on the class labels on the image sites. However, instead of assuming the conditional independence of the observed data, we propose to capture the local dependencies in the data using a multiscale feature vector. The distribution of the multiscale feature vectors is modeled as mixture of Gaussians. A set of robust multi-scale features is presented that captures the general statistical properties of man-made structures at multiple scales without relying on explicit edge detection. The proposed approach was validated on real-world images from the Corel data set, and a performance comparison with other techniques is presented.
10689850
Discriminative random fields: a discriminative framework for contextual interaction in classification
In this work we present discriminative random fields (DRFs), a discriminative framework for the classification of image regions by incorporating neighborhood interactions in the labels as well as the observed data. The discriminative random fields offer several advantages over the conventional Markov random field (MRF) framework. First, the DRFs allow to relax the strong assumption of conditional independence of the observed data generally used in the MRF framework for tractability. This assumption is too restrictive for a large number of applications in vision. Second, the DRFs derive their classification power by exploiting the probabilistic discriminative models instead of the generative models used in the MRF framework. Finally, all the parameters in the DRF model are estimated simultaneously from the training data unlike the MRF framework where likelihood parameters are usually learned separately from the field parameters. We illustrate the advantages of the DRFs over the MRF framework in an application of man-made structure detection in natural images taken from the Corel database.
132053
Performance directed energy management for main memory and disks
Much research has been conducted on energy management for memory and disks. Most studies use control algorithms that dynamically transition devices to low power modes after they are idle for a certain threshold period of time. The control algorithms used in the past have two major limitations. First, they require painstaking, application-dependent manual tuning of their thresholds to achieve energy savings without significantly degrading performance. Second, they do not provide performance guarantees. In one case, they slowed down an application by 835.This paper addresses these two limitations for both memory and disks, making memory/disk energy-saving schemes practical enough to use in real systems. Specifically, we make three contributions: (1) We propose a technique that provides a performance guarantee for control algorithms. We show that our method works well for all tested cases, even with previously proposed algorithms that are not performance-aware. (2) We propose a new control algorithm, Performance-directed Dynamic (PD), that dynamically adjusts its thresholds periodically, based on available slack and recent workload characteristics. For memory, PD consumes the least energy, when compared to previous hand-tuned algorithms combined with a performance guarantee. However, for disks, PD is too complex and its self-tuning is unable to beat previous hand-tuned algorithms. (3) To improve on PD, we propose a simple, optimization-based, threshold-free control algorithm, Performance-directed Static (PS). PS periodically assigns a static configuration by solving an optimization problem that incorporates information about the available slack and recent traffic variability to different chips/disks. We find that PS is the best or close to the best across all performanceguaranteed disk algorithms, including hand-tuned versions.
7470034
Recognition of human actions using moment based features and artificial neural networks
This paper presents performance of view-based approach in automated recognition of predefined hand and gross body actions using artificial neural network. This approach represents motion by a static grey scale image template computed by collapsing the temporal components into the cumulative image-difference of frames. The seven invariant Hu moments are used as the feature vectors. The performance of the system is tested in real time using feed forward multilayer perceptron (MLP) based on back propagation.
8599048
A framework for collective personalized communication
The paper explores collective personalized communication. For example, in all-to-all personalized communication (AAPC), each processor sends a distinct message to every other processor. However, for many applications, the collective communication pattern is many-to-many, where each processor sends a distinct message to a subset of processors. We first present strategies that reduce per-message cost to optimize AAPC. We then present performance results of these strategies in both all-to-all and many-to-many scenarios. These strategies are implemented in a flexible, asynchronous library with a non-blocking interface, and a message-driven runtime system. This allows the collective communication to run concurrently with the application, if desired. As a result the computational overhead of the communication is substantially reduced, at least on machines such as PSC Lemieux, which sport a co-processor capable of remote DMA. We demonstrate the advantages of our framework with performance results on several benchmarks and applications.
26327552
Increased watermark-to-host correlation of uniform random phase watermarks in audio signals
We analyze the watermark-to-host correlation (WHC) of random phase watermarks, in the context of additive embedding and blind correlation-detection of the watermark in audio signals. Interestingly, we find that WHC is higher when a legitimate watermark is present in the audio signal. Instead of trying to minimize the WHC, one could also attempt to harness this increased correlation in order to result in better detection performance. The analysis shows that uniformly distributed phase difference (between the host signal and the watermark) provides maximum advantage. It is also verified that, a uniformly distributed watermark phase provides the most advantage, experimented over a variety of audio signals.
15130627
Using model checking to debug device firmware
Device firmware is a piece of concurrent software that achieves high performance at the cost of software complexity. They contain subtle race conditions that make them difficult to debug using traditional debugging techniques. The problem is further compounded by the lack of debugging support on the devices. This is a serious problem because the device firmware is trusted by the operating system.Model checkers are designed to systematically verify properties of concurrent systems. Therefore, model checking is a promising approach to debugging device firmware. However, model checking involves an exponential search. Consequently, the models have to be small to allow effective model checking.This paper describes the abstraction techniques used by the ESP compiler to extract abstract models from device firmware written in ESP. The abstract models are small because they discard some of the details in the firmware that is irrelevant to the particular property being verified. The programmer is required to specify the abstractions to be performed. The ESP compiler uses the abstraction specification to extract models conservatively. Therefore, every bug in the original program will be present in the extracted model.This paper also presents our experience with using Spin model checker to develop and debug VMMC firmware for the Myrinet network interfaces. An earlier version of the ESP compiler yielded models that were too large to check for system-wide properties like absence of deadlocks. The new version of the compiler generated abstract models that were used to identify several subtle bugs in the firmware. So far, we have not encountered any bugs that were not caught by Spin.