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Detection of visually salient image regions is useful for applications like object segmentation, adaptive compression, and object recognition. In this paper, we introduce a method for salient region detection that outputs full resolution saliency maps with well-defined boundaries of salient objects. These boundaries are preserved by retaining substantially(More)
This paper presents an efficient metric for quantifying the visual fidelity of natural images based on near-threshold and suprathreshold properties of human vision. The proposed metric, the visual signal-to-noise ratio (VSNR), operates via a two-stage approach. In the first stage, contrast thresholds for detection of distortions in the presence of natural(More)
Assumptions about image continuity lead to oversmoothed edges in common image interpolation algorithms. A wavelet-based interpolation method that imposes no continuity constraints is introduced. The algorithm estimates the regularity of edges by measuring the decay of wavelet transform coefficients across scales and preserves the underlying regularity by(More)
We introduce a new class of multiple description scalar quantizer (MDSQ), which will be referred to as the modified MDSQ (MMDSQ). The structure of MMDSQ is fundamentally different from the MDSQ proposed by Vaishampayan. Analysis shows that at high rates for sources with smooth pdfs, MMDSQ achieves the same performance as entropy-constrained MDSQ using a(More)
Transmission of still images and video over lossy packet networks presents a reconstruction problem at the decoder. Specifically, in the case of block-based transform coded images, loss of one or more packets due to network congestion or transmission errors can result in errant or entirely lost blocks in the decoded image. This article proposes a(More)
A psychophysical experiment is described that quantifies human sensitivities to suprathreshold distortions caused by wavelet coefficient quantization in natural images, and the resulting analysis is explained. The quantizer step sizes that cause the first three visible degradations relative to the original image are well predicted by exponential functions(More)
This paper introduces a new high-rate analysis of the multiple description scalar quantizer (MDSQ) with balanced descriptions. The analysis provides insight into the structure of the MDSQ, suggesting the nonoptimality of uniform central quantizer cell lengths, as well as a method to approximate optimal cell lengths. For both level-constrained and(More)
Latent variable models of functional somatic symptoms were estimated for a sample of 686 family medicine patients. Symptom items from the NIMH Diagnostic Interview Schedule were selected to approximate diagnoses of fibromyalgia syndrome (FMS), chronic fatigue syndrome (CFS), and irritable bowel syndrome (IBS). Confirmatory factor analysis demonstrated that(More)
Quantization of the coefficients within a discrete wavelet transform subband gives rise to distortions in the reconstructed image that are localized in spatial frequency and orientation and are spatially correlated with the image. We investigated the detectability of these distortions: Contrast thresholds were measured for both simple and compound(More)