107 research outputs found
Effect of Color Space on High Dynamic Range Video Compression Performance
High dynamic range (HDR) technology allows for capturing and delivering a greater range of luminance levels compared to traditional video using standard dynamic range (SDR). At the same time, it has brought multiple challenges in content distribution, one of them being video compression. While there has been a significant amount of work conducted on this topic, there are some aspects that could still benefit this area. One such aspect is the choice of color space used for coding. In this paper, we evaluate through a subjective study how the performance of HDR video compression is affected by three color spaces: the commonly used Y'CbCr, and the recently introduced ITP (ICtCp) and Ypu'v'. Five video sequences are compressed at four bit rates, selected in a preliminary study, and their quality is assessed using pairwise comparisons. The results of pairwise comparisons are further analyzed and scaled to obtain quality scores. We found no evidence of ITP improving compression performance over Y'CbCr. We also found that Ypu'v' results in a moderately lower performance for some sequences
The preferred system gamma is primarily determined by the ratio of dynamic range of the original scene and the displayed image
The dynamic range of real world scenes may vary from
around 102
to greater than 107
, whilst the dynamic range of monitors
may vary from 102
to 105
. In this paper, we investigate the
impact of the dynamic range ratio (DRratio) between the captured
scene and the displayed image, upon the value of system gamma
preferred by subjects (a simple global power law transformation
applied to the image). To do so, we present an image dataset
with a broad distribution of dynamic ranges upon various subranges
of a SIM2 monitor. The full dynamic range of the monitor
is 105 and we present images using either the full range, 75% or
50% of this, while maintaining a fixed mid-luminance level. We
find that the preferred system gamma is inversely correlated with
the DRratio and importantly, is one (linear) when the DRratio is
one. This strongly suggests that the visual system is optimized
for processing images only when the dynamic range is presented
correctly. The DRratio is not the only factor. By using 50% of
the monitor dynamic range and using either the lower, middle or
upper portion of the monitor, we show that increasing the overall
luminance level also increases the preferred system gamma,
although to a lesser extent than the DR ratio
Root Fractures in the Primary Teeth and Their Management: A Scoping Review
(1) Background: Traumatic dental injuries constitute a major global health problem. Primary deciduous teeth of the upper frontal group are frequently affected by trauma, especially at an early age. It is important to treat primary traumatic injuries because early tooth loss can lead to aesthetic and functional alterations. The most common injuries are extrusion, lateral luxation, and intrusion. Root fracture is a less common complication that can lead to tooth extraction if not properly diagnosed and managed. However, there are a lack of data regarding primary root fracture treatment. The literature was reviewed to study the current knowledge on the treatment of these injuries, and to propose an operative protocol based on the results obtained. (2) Methods: A literature search was performed on Web of Science, PubMed/MEDLINE, and SCOPUS. The research focused on the following features: age of the patient; localization of the root fracture and type of displacement suffered (intrusive, extrusive, or lateral); type of emergency treatment or diagnostic test performed and their compliance with IADT guidelines; follow-up duration. (2) Results: Only 8 articles fully met the inclusion criteria, with a total of 46 patients and 62 root fractures. Out of a total of 62 root fractures, regarding only upper incisors, the most common treatment was splinting (n = 39) for a period ranging from 3 weeks to 3 months (with an average of six weeks). No treatment was performed for 23 of the root fractures. The splinting performed in most of the included cases was semi-rigid, with the splint held in place using a composite resin material. An orthodontic splint using brackets and 0.5 mm stainless steel wire was used in only in one study. (4) Conclusions: We deduced that the root fracture of primary teeth is a rare traumatic dental injury that can cause numerous complications, such as eruptive problems in the permanent teeth. Correct radiological diagnosis, immediate repositioning and semi-rigid splinting could be conservative methods to prevent premature tooth loss in very young patients
The relation between MOS and pairwise comparisons and the importance of cross-content comparisons
© 2018, Society for Imaging Science and Technology. Subjective quality assessment is considered a reliable method for quality assessment of distorted stimuli for several multimedia applications. The experimental methods can be broadly categorized into those that rate and rank stimuli. Although ranking directly provides an order of stimuli rather than a continuous measure of quality, the experimental data can be converted using scaling methods into an interval scale, similar to that provided by rating methods. In this paper, we compare the results collected in a rating (mean opinion scores) experiment to the scaled results of a pairwise comparison experiment, the most common ranking method. We find a strong linear relationship between results of both methods, which, however, differs between content. To improve the relationship and unify the scale, we extend the experiment to include cross-content comparisons. We find that the cross-content comparisons reduce the confidence intervals for pairwise comparison results, but also improve the relationship with mean opinion scores
Diagnosis of obstructive sleep apnea with respiratory polygraph in hypercapnic ICU patients
The role of the emergency medical dispatch centre (EMDC) and prehospital emergency care safety: results from an incident report (IR) system
Introduction The role of the emergency medical dispatch centre (EMDC) is essential to ensure coordinated and safe prehospital care. The aim of this study was to implement an incident report (IR) system in prehospital emergency care management with a view to detecting errors occurring in this setting and guiding the implementation of safety improvement initiatives
Framing tourist risk in UK press accounts of Hurricane Ivan
This article examines the coverage of selected UK press reports of Hurricane Ivan in September 2004 that was the most powerful storm to hit the Caribbean within the last 10 years. Quantitative content analysis has been utilised in this study to determine the main sources of information on the Hurricane and to examine the framing of tourist risk in the press accounts of this disaster. It is demonstrated that the reporting of Hurricane Ivan in the news items tended to convey information that amplified tourist vulnerability and risk. Institutional official sources were often quoted to reinforce danger and ‘no-escape’ rather than reporting on management strategies to reduce these risks or measures that were implemented to ensure visitor safety. This article therefore contends that media management strategies on disasters need to employ more precise and careful monitoring of media accounts of disasters in major generating markets. Such activities may be invaluable in providing assistance to tourism managers regarding decisions on communications strategies and marketing activity aimed at repairing damage and returning to normality in an affected country or region
Erratum to: 36th International Symposium on Intensive Care and Emergency Medicine
[This corrects the article DOI: 10.1186/s13054-016-1208-6.]
Global patient outcomes after elective surgery: prospective cohort study in 27 low-, middle- and high-income countries.
BACKGROUND: As global initiatives increase patient access to surgical treatments, there remains a need to understand the adverse effects of surgery and define appropriate levels of perioperative care. METHODS: We designed a prospective international 7-day cohort study of outcomes following elective adult inpatient surgery in 27 countries. The primary outcome was in-hospital complications. Secondary outcomes were death following a complication (failure to rescue) and death in hospital. Process measures were admission to critical care immediately after surgery or to treat a complication and duration of hospital stay. A single definition of critical care was used for all countries. RESULTS: A total of 474 hospitals in 19 high-, 7 middle- and 1 low-income country were included in the primary analysis. Data included 44 814 patients with a median hospital stay of 4 (range 2-7) days. A total of 7508 patients (16.8%) developed one or more postoperative complication and 207 died (0.5%). The overall mortality among patients who developed complications was 2.8%. Mortality following complications ranged from 2.4% for pulmonary embolism to 43.9% for cardiac arrest. A total of 4360 (9.7%) patients were admitted to a critical care unit as routine immediately after surgery, of whom 2198 (50.4%) developed a complication, with 105 (2.4%) deaths. A total of 1233 patients (16.4%) were admitted to a critical care unit to treat complications, with 119 (9.7%) deaths. Despite lower baseline risk, outcomes were similar in low- and middle-income compared with high-income countries. CONCLUSIONS: Poor patient outcomes are common after inpatient surgery. Global initiatives to increase access to surgical treatments should also address the need for safe perioperative care. STUDY REGISTRATION: ISRCTN5181700
Emphysematous cholecystitis presenting as gas-forming liver abscess and pneumoperitoneum in a dialysis patient: a case report and review of the literature
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