Author: 廖家麟Publisher:
ISBN:
Category :
Languages : en
Pages : 40
Book Description
Low-Distortion Perceptual-Based Tone Mapping and Detail Enhancement
Author: 廖家麟Perceptually Based Tone Mapping for Low-Light Conditions
Author: Adam KirkPublisher:
ISBN:
Category :
Languages : en
Pages : 104
Book Description
We present a perceptually based algorithm for modeling the color shift that occurs for human viewers in low-light scenes. Known as the Purkinje effect, this color shift occurs as the eye transitions from photopic, cone-mediated vision in well-lit scenes to scotopic, rod-mediated vision in dark scenes. At intermediate light levels vision is mesopic with both the rods and cones active. Although the rods have a spectral response distinct from the cones, they still share the same neural pathways. As light levels decrease and the rods become increasingly active they cause a perceived shift in color. We model this process so that we can compute perceived colors for mesopic and scotopic scenes from spectral data. While our tone mapping operator works with spectral data from any source, we show how to produce spectral data of static scenes using multiple images and a camera with known spectral sensitivity. If the spectral sensitivity isn't provided by the camera manufacturer, we describe a one-time calibration procedure to estimate the sensitivity. Should obtaining spectral data of a scene be infeasible, we also describe how the effect can be approximated from high dynamic range RGB images by learning a mapping from RGB to rod and cone responses. Once we have determined rod and cone responses either directly or through our approximation process, we map them to RGB values that can be displayed on a standard monitor to elicit the same color perception when viewed photopically. Our tone mapping method focuses on computing the color shift associated with low-light conditions and leverages current HDR techniques to control the image dynamic range. We include results generated from both spectral and RGB images as well as experimental data.
Objective Image Quality Assessment Based Tone Mapping Optimization
Author: Xihe GaoPublisher:
ISBN:
Category :
Languages : en
Pages : 0
Book Description
High dynamic range (HDR) images provide the capacity to represent the luminance in real scenes with much higher precision than standard image formats. With advances in hardware and computer graphics technologies, HDR images are rapidly becoming more commonplace. To visualize HDR images on contemporary display devices, the dynamic range needs to be adapted to the much smaller range of the devices. This is accomplished through tone mapping, with the goal of reproducing the visual appearance of HDR scenes. Tone mapping has attracted much attention and several dozens of tone mapping operators have been proposed. Nevertheless, it remains challenging to objectively evaluate the quality of tone mapped images and optimize tone mapping operators with automated algorithms. Using virtual photographs to bridge the gap of dynamic ranges for feature analysis, we propose two feature-based quality metrics for tone mapped images, which measure the distortion of important image features that affect the perceived quality. We present an image quality metric called visual saliency distortion predictor (VSDP) that measures the distortion in visual saliency for quality assessment. Additionally, by incorporating multiple feature-based measures to predict the quality of tone mapped images, we introduce another quality metric: perceptual distortion predictor (PDP). Subjective and numerical experiments indicate that the proposed feature-based quality metrics can yield more reliable prediction than the alternative approaches. Once suitable quality metrics are defined, there emerges an opportunity to automate the tuning of existing tone mapping operators. By minimizing the distortion in visual saliency predicted by the quality metric VSDP, we developed an automatic parameter tuning algorithm for tone mapping operators. Moreover, based on the quality prediction of PDP, we propose an automated blended tone mapping algorithm which blends images from multiple operators with varying weights to leverage the strengths of each of operators considered. Experiments with a broad range of HDR images and statistical analysis demonstrate the effectiveness of the tone mapping optimization algorithms.
The high dynamic range imaging pipeline
Author: Gabriel EilertsenPublisher: Linköping University Electronic Press
ISBN: 9176853020
Category :
Languages : en
Pages : 155
Book Description
Techniques for high dynamic range (HDR) imaging make it possible to capture and store an increased range of luminances and colors as compared to what can be achieved with a conventional camera. This high amount of image information can be used in a wide range of applications, such as HDR displays, image-based lighting, tone-mapping, computer vision, and post-processing operations. HDR imaging has been an important concept in research and development for many years. Within the last couple of years it has also reached the consumer market, e.g. with TV displays that are capable of reproducing an increased dynamic range and peak luminance. This thesis presents a set of technical contributions within the field of HDR imaging. First, the area of HDR video tone-mapping is thoroughly reviewed, evaluated and developed upon. A subjective comparison experiment of existing methods is performed, followed by the development of novel techniques that overcome many of the problems evidenced by the evaluation. Second, a largescale objective comparison is presented, which evaluates existing techniques that are involved in HDR video distribution. From the results, a first open-source HDR video codec solution, Luma HDRv, is built using the best performing techniques. Third, a machine learning method is proposed for the purpose of reconstructing an HDR image from one single-exposure low dynamic range (LDR) image. The method is trained on a large set of HDR images, using recent advances in deep learning, and the results increase the quality and performance significantly as compared to existing algorithms. The areas for which contributions are presented can be closely inter-linked in the HDR imaging pipeline. Here, the thesis work helps in promoting efficient and high-quality HDR video distribution and display, as well as robust HDR image reconstruction from a single conventional LDR image.
High Dynamic Range Video
Author: Frédéric DufauxPublisher: Academic Press
ISBN: 0128030399
Category : Computers
Languages : en
Pages : 631
Book Description
At the time of rapid technological progress and uptake of High Dynamic Range (HDR) video content in numerous sectors, this book provides an overview of the key supporting technologies, discusses the effectiveness of various techniques, reviews the initial standardization efforts and explores new research directions in all aspects involved in HDR video systems. Topics addressed include content acquisition and production, tone mapping and inverse tone mapping operators, coding, quality of experience, and display technologies. This book also explores a number of applications using HDR video technologies in the automotive industry, medical imaging, spacecraft imaging, driving simulation and watermarking. By covering general to advanced topics, along with a broad and deep analysis, this book is suitable for both the researcher new or familiar to the area. With this book the reader will: Gain a broad understanding of all the elements in the HDR video processing chain Learn the most recent results of ongoing research Understand the challenges and perspectives for HDR video technologies Covers a broad range of topics encompassing the whole processing chain in HDR video systems, from acquisition to display Provides a comprehensive overview of this fast emerging topic Presents upcoming applications taking advantages of HDR
Visual Signal Quality Assessment
Author: Chenwei DengPublisher: Springer
ISBN: 3319103687
Category : Technology & Engineering
Languages : en
Pages : 311
Book Description
This book provides comprehensive coverage of the latest trends/advances in subjective and objective quality evaluation for traditional visual signals, such as 2D images and video, as well as the most recent challenges for the field of multimedia quality assessment and processing, such as mobile video and social media. Readers will learn how to ensure the highest storage/delivery/ transmission quality of visual content (including image, video, graphics, animation, etc.) from the server to the consumer, under resource constraints, such as computation, bandwidth, storage space, battery life, etc.
Encyclopedia of Image Processing
Author: Phillip A. LaplantePublisher: CRC Press
ISBN: 1351032739
Category : Technology & Engineering
Languages : en
Pages : 856
Book Description
The Encyclopedia of Image Processing presents a vast collection of well-written articles covering image processing fundamentals (e.g. color theory, fuzzy sets, cryptography) and applications (e.g. geographic information systems, traffic analysis, forgery detection). Image processing advances have enabled many applications in healthcare, avionics, robotics, natural resource discovery, and defense, which makes this text a key asset for both academic and industrial libraries and applied scientists and engineers working in any field that utilizes image processing. Written by experts from both academia and industry, it is structured using the ACM Computing Classification System (CCS) first published in 1988, but most recently updated in 2012.
Tone Mapping Based on Natural Image Statistics and Visual Perception Models
Author: Praveen CyriacPublisher:
ISBN:
Category :
Languages : en
Pages : 184
Book Description
Les tècniques d'imatge d'alt rang dinàmic (HDR) potencialment permeten la captura i l'emmagatzematge de tota la informació de llum en una escena. No obstant això, els dispositius comuns de visualització són limitats en termes de les seves capacitats de contrast i brillantor, per tant, les imatges HDR han de ser mapejades tonalment abans de presentar-les en un dispositiu de visualització per assegurar que es reprodueix l'aspecte original de l'escena. En aquesta tesi, es prenen dos enfocaments del problema de mapeig tonal. En primer lloc, es desenvolupa un marc general per a la millora de qualsevol imatge mapejada tonalment mitjançant la reducció de la distància a la corresponent imatge HDR en termes d'una mètrica perceptiva no local. La distància es redueix al mínim per mitjà d'un algoritme de descens de gradient. En segon lloc, es desenvolupa un operador de mapeig tonal (TMO) en temps real que s'adapta bé a les estadístiques d'escenes naturals, i concorda amb els nous descobriments psicofísics i dades neurofísiques. Determinem les correctes adaptacions no lineals necessàries per als nostres resultats de mapeig tonal per tal d'obtenir l'aparença òptima en diferents condicions de visualització, a través d'experiments psicofísics i desenvolupar un mètode automàtic per poder predir dades experimentals. El nostre TMO produeix resultats d'aspecte natural, sense cap tipus d'artefactes espacials o temporals. Els tests de preferència dels usuaris mostren que el nostre mètode obté millors resultats en comparació amb les tècniques més recents. El TMO és ràpid i podria ser implementat en el hardware de la càmera. Pot ser utilitzat per al monitoratge de càmeres HDR en pantalles regulars, com a substitut de la correcció gamma, i com una manera de proporcionar al colorista amb contingut que té alhora un aspecte natural i una aparença nítida i clara.
Computational Color Imaging
Author: Alain TrémeauPublisher: Springer Science & Business Media
ISBN: 3642032656
Category : Computers
Languages : en
Pages : 245
Book Description
We would like to welcome you to the proceedings of CCIW 2009, the Computational Color Imaging Workshop, held in Saint-Etienne, France, March 26–27, 2009. This, the second CCIW, was organized by the University Jean Monnet and the - boratoire Hubert Curien UMR 5516 (Saint-Etienne, France) with the endorsement of the International Association for Pattern Recognition (IAPR), the French Association for Pattern Recognition and Interpretation (AFRIF) affiliated with IAPR, and the "Groupe Français de l'Imagerie Numérique Couleur" (GFINC). The first CCIW was organized in 2007 in Modena, Italy, with the endorsement of IAPR. This workshop was held along with the International Conference on Image Analysis and Processing (ICIAP), the main conference on image processing and pattern recognition organized every two years by the Group of Italian Researchers on Pattern Recognition (GIRPR) affiliated with the International Association for Pattern Recognition (IAPR). Our first goal, since we began the planning of the workshop, was to bring together engineers and scientists from various imaging companies and from technical com- nities all over the world to discuss diverse aspects of their latest work, ranging from theoretical developments to practical applications in the field of color imaging, color image processing and analysis. The workshop was therefore intended for researchers and practitioners in the digital imaging, multimedia, visual communications, computer vision, and consumer electronic industry, who are interested in the fundamentals of color image processing and its emerging applications.
Author: Grzegorz Krawczyk