t. This paper surveys some of the work our group has done in electrical impedance tomography.

Electrical Impedance Tomography

Perceptual visual quality metrics: A survey

This work presents a perceptual-based no-reference objective image sharpness/blurriness metric by integrating the concept of just noticeable blur into a probability summation model. Unlike existing objective no-reference image sharpness/blurriness metrics, the proposed metric is able to predict the relative amount of blurriness in images with different content. Results are provided to illustrate the performance of the proposed perceptual-based sharpness metric. These results show that the proposed sharpness metric correlates well with the perceived sharpness being able to predict with high accuracy the relative amount of blurriness in images with different content.

A No-Reference Objective Image Sharpness Metric Based on the Notion of Just Noticeable Blur (JNB)

An improved electrical impedance tomographic reconstruction algorithm is presented that is generally guaranteed to converge. The algorithm is attractive for several reasons. A modified Newton?Raphson method varies a finite-element model of resistivities to fit a set of voltage measurements in a least-squared sense. Two procedures for calculating the Jacobian matrix are derived. One is standard, while the other is based on the compensation theorem. This second procedure is more efficient for computations, and just as accurate as the standard one. The inherent ill-conditioning in the approximate Hessian matrix of the linearized system is eliminated using the Marquardt method. Results from two-dimensional computer simulations are compared to four other reconstruction algorithms, which are based on methods proposed by other authors. The modified Newton?Raphson method provided significantly better reconstructions than any of the other methods. The algorithms compared are the perturbation, equipotential, iterative-equipotential, and the double-constraint methods. The modified Newton?Raphson method was found to be sensitive to measurement error, but future work in designing electrode-probing configurations is expected to reduce this sensitivity.

Comparing Reconstruction Algorithms for Electrical Impedance Tomography

Texture features for image classification and retrieval.

A simulation study of electrical impedance computed tomography is presented. This is an inverse problem. A field is discretized by the finite element method and an iterative approach derived from the sensitivity theorem is examined for leads taken on the field surface. It is shown that the conductivity distribution in the field can be estimated from the impedance data obtained for the body surface leads. Simulation suggests the availability and the limitation for impedance plethysmography application. The finite element model must be chosen properly to provide the unique solution.

Electrical Impedance Computed Tomography Based on a Finite Element Model

The interface boundary between two domains with different conductivity is to be determined from the impedance measured at the domain surface. This is an inverse problem. Two approaches, influence coefficient approach and boundary integral approach, using a boundary element model are presented. To examine the validity of the approaches, numerical experiments are carried out for a two-dimensional field, and the suitability and limitation of the methods for application to impedance plethysmography are discussed.

Boundary element iterative techniques for determining the interface boundary between two Laplace domains—a basic study of impedance plethysmography as an inverse problem

This paper presents a no-reference image quality assessment model for JPEG/JPEG2000 coding. This assessment model are based on the blockiness around the block boundary, the average absolute difference between adjacent pixels within block, and the zero-crossing rate within block. The descrimination of JPEG coded image and JPEG2000 coded image is performed using the information of the blockiness and the average absolute difference between adjacent pixels. For image quality assessment of JPEG2000 coding, the blur measure is introduced instead of the blockiness of JPEG coding.

No-reference image quality assessment for JPEG/JPEG2000 coding

Boundary element models of the vocal tract and radiation field and their response characteristics

To perform Quality of Service (QoS) control of video communication more efficiently, it is necessary to develop an objective quality evaluation method for coded video. Many proposed conventional methods to obtain video quality require the availability of both reference and processed video sequence. However, in case of re-encoding the coded video stream at the receiver side where reference video sequence is not present, it is impossible to do such a full-reference evaluation. Therefore, we have developed a video quality evaluation model by using reduced reference for evaluated value obtained by SSCQE method. In this approach, we use some features extracted from reference video. It is called reduced-reference method by VQEG. Transmitting these features with coded video, the proposed model can estimate the video quality, even in the absent of the full original video in the decoder side. The video quality rating obtained from the proposed model shows good agreement with subjective quality.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Tadakuni Murai

Papers

Electrical Impedance Computed Tomography Based on a Finite Element Model

Boundary element iterative techniques for determining the interface boundary between two Laplace domains—a basic study of impedance plethysmography as an inverse problem

No-reference image quality assessment for JPEG/JPEG2000 coding

Boundary element models of the vocal tract and radiation field and their response characteristics

Evaluation model considering static-temporal quality degradation and human memory for SSCQE video quality