A functional model of similarity

In the first chapters, the prevalent conception of the nature of similarity is shown to be too narrow, and the argument is developed that models of similarity must encompass both analytic and synthetic components. Some general problems of measurement and the testing of psychological models are also discussed.A review of the philosophical treatment of the concept of similarity is made in order to understand the origins of the models found in the present psychological literature. These are then analysed in terms of their implicit object representations and cognitive processes. The distinction between the'class inclusion' and 'distance relation' models of similarity is shown tobe qualitative in nature, and to correspond to the analytic-synthetic distinction in terms of cognitive process.A functional model of the psychological processes and object representations involved in similarity judgements is then proposed. The fundamental idea involved in this model is that the global properties of referents are synthetically evaluated in terms of their contextual relations, whilst an analytic 'pattern matching' of local properties is made. Various theoretical aspects of the model are examined experimentally, and its general applicability is indicated in a series of applied studies.The scope of the argument is finally broadened to encompass a development of Torgerson's (196.5) conception of the nature of the dimensions resulting from MDS analysis. Dimensions may be considered as 'virtual' artifacts of the experimental task and the individual's conception of it. This possibility allows the methodology to escape the dominating influence of its psychophysical tradition, and become a conceptually deeper tool for cognitive psychology

Development and evaluation of deep learning algorithms for assessment of acute burns and the need for surgery

Assessment of burn extent and depth are critical and require very specialized diagnosis. Automated image-based algorithms could assist in performing wound detection and classification. We aimed to develop two deep-learning algorithms that respectively identify burns, and classify whether they require surgery. An additional aim assessed the performances in different Fitzpatrick skin types. Annotated burn (n = 1105) and background (n = 536) images were collected. Using a commercially available platform for deep learning algorithms, two models were trained and validated on 70% of the images and tested on the remaining 30%. Accuracy was measured for each image using the percentage of wound area correctly identified and F1 scores for the wound identifier; and area under the receiver operating characteristic (AUC) curve, sensitivity, and specificity for the wound classifier. The wound identifier algorithm detected an average of 87.2% of the wound areas accurately in the test set. For the wound classifier algorithm, the AUC was 0.885. The wound identifier algorithm was more accurate in patients with darker skin types; the wound classifier was more accurate in patients with lighter skin types. To conclude, image-based algorithms can support the assessment of acute burns with relatively good accuracy although larger and different datasets are needed.Peer reviewe

Inverse tone mapping

The introduction of High Dynamic Range Imaging in computer graphics has produced a novelty in Imaging that can be compared to the introduction of colour photography or even more. Light can now be captured, stored, processed, and finally visualised without losing information. Moreover, new applications that can exploit physical values of the light have been introduced such as re-lighting of synthetic/real objects, or enhanced visualisation of scenes. However, these new processing and visualisation techniques cannot be applied to movies and pictures that have been produced by photography and cinematography in more than one hundred years. This thesis introduces a general framework for expanding legacy content into High Dynamic Range content. The expansion is achieved avoiding artefacts, producing images suitable for visualisation and re-lighting of synthetic/real objects. Moreover, it is presented a methodology based on psychophysical experiments and computational metrics to measure performances of expansion algorithms. Finally, a compression scheme, inspired by the framework, for High Dynamic Range Textures, is proposed and evaluated

Appearance-based image splitting for HDR display systems

High dynamic range displays that incorporate two optically-coupled image planes have recently been developed. This dual image plane design requires that a given HDR input image be split into two complementary standard dynamic range components that drive the coupled systems, therefore there existing image splitting issue. In this research, two types of HDR display systems (hardcopy and softcopy HDR display) are constructed to facilitate the study of HDR image splitting algorithm for building HDR displays. A new HDR image splitting algorithm which incorporates iCAM06 image appearance model is proposed, seeking to create displayed HDR images that can provide better image quality. The new algorithm has potential to improve image details perception, colorfulness and better gamut utilization. Finally, the performance of the new iCAM06-based HDR image splitting algorithm is evaluated and compared with widely spread luminance square root algorithm through psychophysical studies

Signal detection theory in the study of nociceptive and pain perception processes

Signal detection theory (SDT) measures (discriminability and response bias) have been proposed to be valid for determining pain perception changes. The construct validity of SDT measures applied to pain perception studies has been questioned on three grounds: interpretation, methodology and theory. Multiple interpretations are possible for the combinations of discriminability and response bias change when the magnitude-rating scale is used for pain perception studies. This is resolved by utilising the confidence-rating scale. The problem of comparability of results between the two scales is bridged by Irwin & Whitehead's (1991) common analytical framework. The results of this thesis supported the framework's prediction that both scales are comparable. Therefore, the confidencerating scale was used for all studies within this thesis for interpretational clarity. Response bias data were not analysed in this thesis due to data artefacts created by correction methods for zero proportions in response categories. Methodologically, the construct validity of discriminability is influenced by the research design and procedures. Therefore, the following procedures were adopted to address weaknesses in previous studies. The one-interval confidence-rating task was used with a six-category confidence-rating scale and post-trial feedback. Based on a methodological study conducted within this thesis, the trial number was pragmatically reduced from 40 trials to 17 trials per stimulus intensity. This trial number reduction would not alter the mean and variance of the data sufficiently to influence the outcome of inferential statistical testing performed. Due to the novel use of the Quantitative Sensory Testing machine for the signal detection study procedures, accuracy and precision study on the machine was performed. This thesis found that the accuracy, repeatability and reproducibility of the machine in generating noxious thermal stimuli is excellent for the purposes of this thesis. Machine error is eliminated as a major source of variance for the thesis results. Theoretically, critics have challenged the construct validity of discriminability as an indicator of pain perception alteration. This thesis examined this issue in two separate contexts: 1) discriminability change as a correlate of local anaesthesia and, 2) discriminability as a correlate of psychological factors (depression and anxiety) in chronic low back pain (CLBP) sufferers. The results failed to establish the construct validity of discriminability for both contexts. However, the higher discriminability in CLBP sufferers compared to healthy individuals is in contrast to past research and warrant further investigation. This thesis addressed the construct validity issues through theoretical, methodological and interpretational modifications. A more robust analysis of the construct validity issue was facilitated. Caution is recommended on the use of discriminability as a pain perception measure until the construct validity issue has been satisfactorily resolved.sub_phyunpub118_ethesesunpu

Low-level visual processing and its relation to neurological disease

Retinal neurons extract changes in image intensity across space, time, and wavelength. Retinal signal is transmitted to the early visual cortex, where the processing of low-level visual information occurs. The fundamental nature of these early visual pathways means that they are often compromised by neurological disease. This thesis had two aims. First, it aimed to investigate changes in visual processing in response to Parkinson’s disease (PD) by using electrophysiological recordings from animal models. Second, it aimed to use functional magnetic resonance imaging (fMRI) to investigate how low-level visual processes are represented in healthy human visual cortex, focusing on two pathways often compromised in disease; the magnocellular pathway and chromatic S-cone pathway. First, we identified a pathological mechanism of excitotoxicity in the visual system of Drosophila PD models. Next, we found that we could apply machine learning classifiers to multivariate visual response profiles recorded from the eye and brain of Drosophila and rodent PD models to accurately classify these animals into their correct class. Using fMRI and psychophysics, found that measurements of temporal contrast sensitivity differ as a function of visual space, with peripherally tuned voxels in early visual areas showing increased contrast sensitivity at a high temporal frequency. Finally, we used 7T fMRI to investigate systematic differences in achromatic and S-cone population receptive field (pRF) size estimates in the visual cortex of healthy humans. Unfortunately, we could not replicate the fundamental effect of pRF size increasing with eccentricity, indicating complications with our data and stimulus

Análisis de la profundidad de las quemaduras a partir de fotografías

En este proyecto se pretende desarrollar un algoritmo para la clasificación de quemaduras mediante un tratamiento digital de imágenes en color. Así podremos determinar cuáles requerirán un injerto de piel en su tratamiento médico. El trabajo está basado en el artículo Features identification for automatic burn classification (2015) de Carmen Serrano, Rafael Boloix-Tortosa, Tomás Gómez-Cía y Begoña Acha. La utilidad de esta herramienta de ayuda al diagnóstico radica en que el enfermo quemado de manera habitual es atendido en primera instancia por un médico no especializado y, por otro lado, el primer tratamiento es esencial para la correcta evolución del paciente. El algoritmo realiza la extracción de una serie de características, las cuales nos ofrecen la información necesaria para determinar las necesidades en cada caso. Continúa con la realización de un clasificador que nos subdivide las imágenes en dos grupos. Un grupo estará compuesto por las imágenes donde el grado de la quemadura es superficial, que no necesitan injerto de piel. Mientras que el otro estará compuesto por las imágenes de quemaduras de tercer grado y las de segundo grado profundo, que tienen necesidad de injerto de piel. Finaliza con la realización de métodos de selección secuencial para identificar que características tienen el poder más discriminante para clasificar quemaduras.This project intends to develop an algorithm for the classification of burns through a digital treatment of color images. So we can determine which ones will require a skin graft in its medical treatment. The work is based on the article Features identification for automatic burn classification (2015) by Carmen Serrano, Rafael Boloix-Tortosa, Tomás Gómez-Cía and Begoña Acha. The usefulness of this diagnostic tool is that the burned patient is usually treated in the first instance by a nonspecialized doctor and, on the other hand, the first treatment is essential for the correct evolution of the patient. The algorithm performs the extraction of a series of characteristics, which provide us with the necessary information to determine the needs in each case. Continue with the realization of a classifier that subdivides the images into two groups. A group will consist of images where the degree of the burn is superficial, that do not need skin grafting. While the other will consist of images of third-degree burns and deep second-degree burns, which have a need for skin grafting. It ends with the realization of sequential selection methods to identify which features have the most discriminating power to classify burns.Universidad de Sevilla. Grado en Ingeniería de las Tecnologías de Telecomunicació

Inverse tone mapping

The introduction of High Dynamic Range Imaging in computer graphics has produced a novelty in Imaging that can be compared to the introduction of colour photography or even more. Light can now be captured, stored, processed, and finally visualised without losing information. Moreover, new applications that can exploit physical values of the light have been introduced such as re-lighting of synthetic/real objects, or enhanced visualisation of scenes. However, these new processing and visualisation techniques cannot be applied to movies and pictures that have been produced by photography and cinematography in more than one hundred years. This thesis introduces a general framework for expanding legacy content into High Dynamic Range content. The expansion is achieved avoiding artefacts, producing images suitable for visualisation and re-lighting of synthetic/real objects. Moreover, it is presented a methodology based on psychophysical experiments and computational metrics to measure performances of expansion algorithms. Finally, a compression scheme, inspired by the framework, for High Dynamic Range Textures, is proposed and evaluated.EThOS - Electronic Theses Online ServiceEngineering and Physical Sciences Research Council (EPSRC) (EP/D032148)GBUnited Kingdo

Aerospace Medicine and Biology: A cumulative index to the 1974 issues of a continuing bibliography

This publication is a cumulative index to the abstracts contained in supplements 125 through 136 of Aerospace Medicine and Biology: A Continuing Bibliography. It includes three indexes--subject, personal author, and corporate source