Fully-automatic inverse tone mapping algorithm based on dynamic mid-level tone mapping

High Dynamic Range (HDR) displays can show images with higher color contrast levels and peak luminosities than the common Low Dynamic Range (LDR) displays. However, most existing video content is recorded and/or graded in LDR format. To show LDR content on HDR displays, it needs to be up-scaled using a so-called inverse tone mapping algorithm. Several techniques for inverse tone mapping have been proposed in the last years, going from simple approaches based on global and local operators to more advanced algorithms such as neural networks. Some of the drawbacks of existing techniques for inverse tone mapping are the need for human intervention, the high computation time for more advanced algorithms, limited low peak brightness, and the lack of the preservation of the artistic intentions. In this paper, we propose a fully-automatic inverse tone mapping operator based on mid-level mapping capable of real-time video processing. Our proposed algorithm allows expanding LDR images into HDR images with peak brightness over 1000 nits, preserving the artistic intentions inherent to the HDR domain. We assessed our results using the full-reference objective quality metrics HDR-VDP-2.2 and DRIM, and carrying out a subjective pair-wise comparison experiment. We compared our results with those obtained with the most recent methods found in the literature. Experimental results demonstrate that our proposed method outperforms the current state-of-the-art of simple inverse tone mapping methods and its performance is similar to other more complex and time-consuming advanced techniques

An Investigation of Daylighting Performance in Sidelit Spaces

The positive influence of daylight on people’s work and well-being has been confirmed in many studies. However, excessive daylight causes discomfort glare, which decreases work productivity, impairs occupants’ vision, and may even cause headaches. Substantial studies explored glare by correlating physical lighting measurements and subjective evaluations. With the development of High Dynamic Range (HDR) image techniques, dynamic changes of daylighting distributions can be effectively captured. Consequently, more studies paired HDR image techniques with subject evaluations to explore glare. However, studies merely relying on field measurements are not only time-consuming and labor-intensive but may also disturb occupants. To address these problems, this dissertation proposed the method of integrating three research tools, HDR image techniques, simulations, and questionnaire surveys, to investigate daylight glare. Using sidelit spaces across five buildings as the example, this dissertation aimed to demonstrate the accuracy of simulation results and the correlations between subject occupant evaluations and physical lighting data derived from both field measurements and simulation results. This dissertation is comprised of three sections. The first section focused on field measurements. Over 200 HDR images across five buildings were taken and analyzed using select visual discomfort metrics. The results showed that daylight glare probability (DGP) outperformed the other visual discomfort metrics in terms of identifying intolerable and imperceptible glare. The second section utilized these HDR images to calibrate four of the five buildings’ Radiance models. The relative RMSE of simulated vertical eye illuminance under both the Perez all-weather sky model and the hybrid photo-radiometer sky model were 23.7% and 21.2%, respectively. The frequencies of accurate glare prediction under both sky models were 93.9% and 95.5%, respectively. The results indicated that Radiance models with precise geometries and material properties can accurately represent the real lighting environments. Finally, the third section paired questionnaire surveys with both the HDR image technique and simulations to investigate daylight qualities within an open-plan office. The study found that taller windows, proximity to windows, and facing towards windows caused severe glare. By removing workstation partitions and arranging seating orientations perpendicular to the windows, the renovated layout design increased occupant satisfaction with their daylighting environments and tolerance for daylight glare. The last section demonstrated the effectiveness of integrating the three tools in lighting studies and the importance of interior layout and furniture designs in terms of daylight glare reduction

HDR video past, present and future : a perspective

High Dynamic Range (HDR) video has emerged from research labs around the world and entered the realm of consumer electronics. The dynamic range that a human can see in a scene with minimal eye adaption (approximately 1,000,000: 1) is vastly greater than traditional imaging technology which can only capture about 8 f-stops (256: 1). HDR technology, on the other hand, has the potential to capture the full range of light in a scene; even more than a human eye can see. This paper examines the field of HDR video from capture to display; past, present and future. In particular the paper looks beyond the current marketing hype around HDR, to show how HDR video in the future can and, indeed, should bring about a step change in imaging, analogous to the change from black and white to colour

HDR-kuvien artefaktit ja niiden poistaminen

Valokuvausteknologian kehittyessä kuvilta vaaditaan yhä parempaa laatua. Kuvien pitää olla verrattavissa subjektiivisesti silmällä nähtävään maailmaan. Kun valokuvilta vaaditaan lähes välitön kuvien otto ja täydellinen lopputulos, pitää kaikkien kuvanmuokkausteknologioiden kehittyä sekä tehokkuudeltaan että virheettömyydeltä. Haastavissa olosuhteissa kameralla on vaikea saada yhteen kuvaan kaikki yksityiskohdat ja suuret valotuserot näkyviin, vaikka silmin katsottuna näkymä näyttäisikin normaalilta. Tähän ongelmaan kehitettiin kuvien päällekkäin asettelu -menetelmä, jolla mahdollistetaan useasta kuvasta yksityiskohtien kerääminen eri valotuksen alueilta. Erilaisten menetelmien avulla voidaan useasta eri tavoin valotetusta kuvasta luoda parempilaatuinen eli niin sanottu HDR-kuva, joka sisältää laajemman skaalan eritasoista valoa ja sävyjä ja näyttää samalta silmin katsottuna kuin maailma. Vaikka tämä prosessi tuottaa virheettömiä kuvia täydellisissä olosuhteissa, kuvaustilanteissa voi tapahtua liikettä sekä kohteessa että kamerassa. Muutkin kuvaustilanteen ulkopuoliset asiat voivat vaikuttaa otettuihin kuviin. Näiden seikkojen takia kuvien yhdistelyprosessi voi luoda erilaisia laatuvirheitä kuviin. Kuvien laatuvirheiden eli artefaktien poistoon on luotu laaja määrä prosesseja, joiden avulla pyritään samaan kuva mahdollisimman virheettömäksi, mutta silti hyvän ja todellisen näköiseksi. Ongelmaan on luotu prosesseja, jotka perustuvat eri lähtökohtiin ja ratkaisevat ongelman eri osa-alueita erilaisilla tuloksilla ja tehokkuudella. Tässä työssä tutkitut tekniikat kykenevät poistamaan kyseiset laatuvirheet kuvista, vaikka niiden suorituskyky vaihtelee kuvan virheellisyyden ja kuvan laadun välillä. Erilaiset kuvienkäsittelyprosessit ovat kompromissi virheettömyyden ja kuvan dynaamisen alueen välillä, jotka yhdessä luovat kuvan subjektiivisen ulkonäön. Prosessit on myös optimoitu tiettyihin kuvaustilanteiden virheisiin, jolloin niiden käyttökohteet kannattaa erikseen valita. Prosessien monimutkaisuus ja samalla niiden suoritusaika vaihtelee suuresti. Tämä työ kuvailee, kuinka HDR-prosessia varten voi ottaa kuvia. Työn tavoite on tutkia, miten erilaiset asiat kuvaustilanteessa ja sen ulkopuolella mahdollistavat artefaktien muodostumisen kuviin niiden prosessoinnissa ja miten kuvien artefakteista pääsee eroon. Työ myös kuvailee, mitä eri asioita on pyritty optimoimaan eri tavoissa poistaa artefakteja kuvista

Characterization of Physical and Dosimetric Aspects of SRS HyperArc Treatment Technique

HyperArc is a radiation therapy planning technique using stereotactic radiosurgical doses delivered via single isocenter volumetric modulated arcs (VMAT) for multi-lesion brain cancer. Due to the nature of these types of treatments it is imperative that the proper quality assurance is completed to ensure the safety of the patient. Geometric limits were assessed using a dose volume histogram (DVH) and known rotational errors of theoretical lesions of different dimensions and lengths from the isocenter. Dosimetric comparisons were evaluated using an ion chamber and Gafchromic EBT-XD film and portal dosimetry. The conclusions from these investigations were that patient rotation will result in a loss of target coverage, which is emphasized for smaller targets and isocenter placement farther away from the lesion. The use of a six degree of freedom (6DoF) couch for set-up and surface tracking during beam delivery reliably positions patients to avoid positioning errors that would degrade treatment outcomes. HyperArc is a user-friendly clinical tool that can be confidently used in a clinical setting when the limitations are well known to the user

Exploring and Expressing Points in Time through iPhoneography

The purpose of this thesis is to examine how iPhoneography extends a personal expression of lights, lines, patterns previously captured on film and digital devices through arts-based research that includes social media feedback. This thesis explores the elements of photographing fleeting moments of time using new technology. This work investigates how to capture moments from daily life through recording the essence of light on surfaces and objects. Images arise from spontaneous and/or semi-spontaneous artistic moments. Visual investigations explore and question light, time, and space, and are categorized into the themes of Shapes, Shadows, and Showers. The work has roots in some of America’s most venerated photographers, who became early inspirations. They include Harry Callahan, Aaron Siskind, Joseph Jachna (a college professor of mine), and Minor White. Their points of view inspired me during my formative years as a photography student and have instilled in me the visual voice I use in my work to this day. Like many of these photographers, I looked locally and across the country for moments in time that moved me. Photographs were captured using an Apple iPhone 5 and 6. Light and easy constant companions, they served accessible tools always in reach and served as a digital sketchbook. The iPhone allowed the capture of the immediacy of the moment using existing light. Kept on High Dynamic Range (HDR) mode, the camera amazingly caught highlight and shadow detail

BCR’s CDP Digital Imaging Best Practices, Version 2.0

This is the published version.These Best Practices — also referred to as the CDP Best Practices -- have been created through the collaboration of working groups pulled from library, museum and archive practitioners. Version 1 was created through funding from the Institute for Museum and Library Services through a grant to the University of Denver and the Colorado Digitization Program in 2003. Version 2 of the guidelines were published by BCR in 2008 and represents a significant update of practices under the leadership of their CDP Digital Imaging Best Practices Working Group. The intent has been to help standardize and share protocols governing the implementation of digital projects. The result of these collaborations is a set of best practice documents that cover issues such as digital imaging, Dublin Core metadata and digital audio. These best practice documents are intended to help with the design and implementation of digitization projects. Because they were collaboratively designed by experts in the field, you can be certain they include the best possible information, in addition to having been field tested and proven in practice. These best practice documents are an ongoing collaborative project, and LYRASIS will add information and new documents as they are developed

The Upland Monitor: April 13, 1916

The April 13, 1916 edition of The Upland Monitor.https://pillars.taylor.edu/monitor-1916-1917/1014/thumbnail.jp