Subjective Quality Evaluation Research Articles

Perceptual intra-frame coding for HEVC still picture profile based on invisible signal suppression

In this paper, a perceptual intra-frame coding for high-efficiency video coding under the still picture profile is proposed to improve coding efficiency in terms of subjective quality. The proposed method suppresses invisible signals based on the just notable distortion (JND) model by maintaining subjective quality with a lower bitrate. For quantized transform coefficients of residual signals, the magnitudes of nonzero coefficients iteratively reduce by 10% and the maximum reduction is decided by the non-noticeable quantized coefficients based on the JND measure with a given quantization parameter. The performance of the proposed algorithm was verified on the HM reference encoder. In the all-intra-configuration of the common test condition, the proposed perceptual encoder achieves a bit saving of 13.87%, on average, and up to 39.52% for several test sequences. The mean difference mean opinion score for subjective quality evaluation is observed approximately 0.64–0.15 with 15 subjects.

Studies on the effect of MegaPixel sensor resolution on displayed image quality and relevant metrics

This paper investigates camera phone image quality, namely the effect of sensor megapixel (MP) resolution on the perceived quality of images displayed at full size on high-quality desktop displays. For the purpose, we use images from simulated cameras with different sensor MP resolutions. We employ methods recommended in the IEEE 1858 Camera Phone Image Quality (CPIQ) standard, as well as other established psychophysical paradigms, to obtain subjective image quality ratings for systems with varying MP resolution from large numbers of observers. These are subsequently used to validate image quality metrics (IQMs) relating to sharpness and resolution, including those from the CPIQ standard. Further, we define acceptable levels of quality - when changing MP resolution - for mobile phone images in Subjective Quality Scale (SQS) units. Finally, we map SQS levels to categories obtained from star-rating experiments (commonly used to rate consumer experience). Our findings draw a relationship between the MP resolution of the camera sensor and the LCD device. The chosen metrics predict quality accurately, but only the metrics proposed by CPIQ return results in calibrated JNDs in quality. We close by discussing the appropriateness of star-rating experiments for the purpose of measuring subjective image quality and metric validation.

Prospective association between suicide cognitions and emotional responses to a laboratory stressor: The mediating role of nightly subjective sleep quality

BackgroundSleep is a reliable correlate of suicidal thoughts and behaviors (STBs), yet few studies have directly examined negative affect in the context of this association. The present study combined daily experience methods with a laboratory paradigm to investigate suicide cognitions as a predictor of emotional responses to environmental stressors, and tested the role of nightly sleep parameters. Method72 participants (Mage = 24.25; 41 with a recent history of suicide ideation and 31 without a history of STBs) completed a four-day study. Suicide cognitions were measured on the first day, and actigraphy-based sleep duration and fragmentation, and morning ratings of prior night subjective sleep quality (SSQ) were subsequently measured over three consecutive nights. Participants returned on the fourth day to complete the Trier Social Stress Task, where self-report changes in negative affect immediately post-task (i.e., reactivity) and five minutes post-task (i.e., recovery) were observed. ResultsRegression analyses indicated that suicide cognitions predicted negative affect reactivity and recovery. Simple mediation analyses revealed that SSQ partially mediated the relation between suicide cognitions and negative affect recovery (especially shame), but not reactivity. No significant associations were observed for the actigraphy-based sleep parameters. LimitationsJust three nights of actigraphy-based data collection. A single item was used to measure SSQ. ConclusionsSuicide cognitions predict negative affective responses to situational stressors and SSQ may have a key role in this effect, especially the duration of negative emotional reactions. Hence, sleep and emotional reactivity may be potential targets for suicide prevention efforts.

Assessment of common errors and subjective quality of digital panoramic radiographs in a dental institution

Aim: The aim of the study was to determine the incidence of patient preparation and positioning errors during panoramic radiographic imaging and to assess the subjective quality of panoramic radiographs in a sample of records collected from a dental institution. Materials and Methods: The study material was 1000 randomly selected panoramic radiographs obtained from the database of the department of oral and maxillofacial radiology. Patient preparation and positioning errors of the radiographs were evaluated and categorized into nine groups. The sample radiographs were also evaluated for subjective quality according to a three-point quality scale by the National Radiological Protection Board (United Kingdom) as “excellent,” “diagnostically acceptable,” or “unacceptable.” Results: Out of 1000 radiographs evaluated, failure to position the tongue against palate was the most common error at 69.5% and patient movement during radiographic exposure was the least common error at 0.4%. As per the subjective quality ratings, 22.4% of the radiograph had excellent quality, 66.4% were diagnostically acceptable, and 13.2% were unacceptable. Conclusion: The incidence of patient positioning errors in the panoramic radiographs was relatively common. The quality of the diagnostic panoramic radiographs could be improved by better operator education and awareness in relation to patient preparation and positioning.

Characteristics of radiographic images acquired with CdTe, CCD and CMOS detectors in skull radiography.

PurposeThe purpose of this study was to evaluate the image quality, diagnostic efficacy, and radiation dose associated with the use of a cadmium telluride (CdTe) detector, compared to charge-coupled device (CCD) and complementary metal oxide semiconductor (CMOS) detectors.Materials and MethodsLateral cephalographs of a phantom (type 1) composed of synthetic polymer filled with water and another phantom (type 2) composed of human skull macerated with polymer coating were obtained with CdTe, CCD, and CMOS detectors. Dosimeters placed on the type 2 phantom were used to measure radiation. Noise levels from each image were also measured. McNamara cephalometric analysis was conducted, the dentoskeletal configurations were assessed, and a subjective evaluation of image quality was conducted. Parametric data were compared via 1-way analysis of variance with the Tukey post-hoc test, with a significance level of 5%. Subjective image quality and dentoskeletal configuration were described qualitatively.ResultsA statistically significant difference was found among the images obtained with the 3 detectors (P<0.05), with the lowest noise level observed among the images obtained with the CdTe detector and a higher subjective preference demonstrated for those images. For the cephalometric analyses, no significant difference (P>0.05) was observed, and perfect agreement was seen with regard to the classifications obtained from the images acquired using the 3 detectors. The radiation dose associated with the CMOS detector was higher than the doses associated with the CCD (P<0.05) and CdTe detectors (P<0.05).ConclusionConsidering the evaluated parameters, the CdTe detector is recommended for use in clinical practice.

Ultra‐low‐dose chest computed tomography without anesthesia in the assessment of pediatric pulmonary diseases

ObjectiveTo evaluate the feasibility of using ultra‐low‐dose computed tomography of the chest with iterative reconstruction without anesthesia for assessment of pulmonary diseases in children. MethodsThis prospective study enrolled 86 consecutive pediatric patients (ranging from 1 month to 18 years) that underwent ultra‐low‐dose computed tomography due to suspicion of pulmonary diseases, without anesthesia and contrast. Parameters used were: 80kVp; 15–30mA; acquisition time, 0.5s; and pitch, 1.375. The adaptive statistical iterative reconstruction technique was used. Subjective visual evaluation and quantitative assessment of image quality were done using a 5‐point scale in 12 different structures of the chest. ResultsMean age was 66 months (interquartile range, 16–147). Final diagnosis was performed in all exams, and 44 (51.2%) were diagnosed with cystic fibrosis, 27 (31.4%) with bronchiolitis obliterans, and 15 (17.4%) with congenital pulmonary airways malformations. Diagnostic quality was achieved in 98.9%, of which 82.6% were considered excellent and 16.3% were slightly blurred but did not interfere with image evaluation. Only one case (1.2%) presented moderate blurring that slightly compromised the image, and previous examinations demonstrated findings compatible with bronchiolitis obliterans. Mean effective radiation dose was 0.39±0.15mSv. Percentages of images with motion artifacts were 0.3% for cystic fibrosis, 1.3% for bronchiolitis obliterans, and 1.1% for congenital pulmonary airways malformations. ConclusionChest ultra‐low‐dose computed tomography without sedation or anesthesia delivering a sub‐millisievert dose can provide image quality to allow identification of common pulmonary anatomy and diseases.

The Effects of Depth of Field on Subjective Evaluation of Aesthetic Appeal and Image Quality of Photographs

Aesthetic appeal and image quality are two important features of photographs, which play the dominant role when people clean their albums. Currently, the objective image quality assessment has been documented very well whereas the objective aesthetic appeal assessment algorithms are not developed well enough. This paper first subjectively evaluated image quality and aesthetic appeal separately of 339 photographs across different levels of depth of field. With the subjective data, the paper proposed two mathematical models to predict the subjective aesthetic appeal from subjective image quality. More specifically, depth of field, as a common photographic feature, was investigated to see how it influenced aesthetic appeal and image quality. 32 participants were asked to score for the aesthetic appeal and image quality. With these subjective scores, we used two methods - linear regression and deep neural networks - to build models separately to predict aesthetic appeal from image quality. We found that both models worked well on the valid dataset and the performance of the deep neural networks model was better than the linear regression model.

A Novel UAV Sensing Image Defogging Method

Imaging of unmanned aerial vehicle easily suffer from haze, resulting in decline in the quality of required remote sensing images. The influence brings great challenges in later analysis and process. Although dark channel prior has acquired substantial achievements, some limitations, including imprecise estimation of atmospheric light, color distortion, and lower brightness of defogging image, still exist. In this article, to target these drawbacks, a novel defogging method for single image is proposed. First, a novel atmospheric scattering model is proposed to define the more accurate atmospheric light by introducing an adaptive variable strategy. Next, unlike traditional dark channel prior, a novel estimation method is presented by fusing dark and light channels to estimate more precise atmospheric light and transmittance. Then, we adopt the gray image corresponding to color image as a guidance image to refine the transmittance to further decrease the time complexity. Aiming at the region of low transmittance, a novel compensation function is created to improve the region of low transmittance and avoid color distortion. Moreover, a simple and effective calculation method is proposed to determine parameters in compensation function. Finally, the clear remote sensing image is established by an improved atmospheric scattering model. Extensive experiments on real-world datasets demonstrate that the proposed method outperforms several other state-of-the-art approaches both on subjective and objective quality evaluations.

The impact of the ones sexuality and autonomy awareness on the insomnia severity in patients with anxiety neurotic disorders

To evaluate an impact of perception of ones sexuality and autonomy on the level of insomnia in patients with neurotic/anxiety disorders. A sample included 123 (93 women and 30 men) patients with neurotic/anxiety disorders (F40, F41, F43, F45) in the age from 25 to 50 years old, anxiety was the main syndrome in the clinical structure of the disorder. Test battery included Pittsburgh Sleep Quality index for the subjective sleep quality evaluation, Insomnia Severity index for stratification of patients into groups with different insomnia level. Anxiety was evaluated with the Hamilton Anxiety Rating Scale. Personality traits, sexuality and sovereignty of psychological space were assessed with the G. Ammon Ego-structure test and the Sovereignty of the individual psychological space questionnaire. Multiple regression analysis was used to study the interrelationship between insomnia severity and psychological characteristics. Insomnia severity index was chosen as the dependent variable. An analysis of the regression model has shown the increase in insomnia index with the simultaneous augmentation of the following scales «Physical body sovereignty», «Sovereignty of objects», «Destructive aggression», «Deficient aggression», «Constructive narcissism», and decrease of the scales «Territory sovereignty», «Deficient narcissism», «Constructive sexuality». The study results imply the importance of the use of the level of sexual functioning and autonomy as the marker of identity maturity for psychotherapeutic targets in the treatment of neurotic/anxiety disorders. The use of anxiety and insomnia as the main complaints can be explained by its societal approval and need further active evaluation by the specialist for the successful psychotherapeutic treatment.

Multi-Focus Image Fusion Using Geometric Algebra Based Discrete Fourier Transform

For color image fusion, existing traditional algorithms regard each color image pixel as a scalar which may lose the relationships among spectral channels. In this paper, a novel multi-focus image fusion algorithm using geometric algebra based Discrete Fourier Transform (GA-DFT) is proposed. First, a novel Discrete Fourier Transform based on geometric algebra (GA) is provided. Second, the proposed algorithm represents the color image as a GA multivector by mapping the RGB channels into the GA space. Third, the variance is selected as a contrast measure to fuse the source images in GA space. The experimental results demonstrate that the proposed algorithm can achieve the comparable performance with its counterparts in terms of subjective quality evaluation, and outperform most of the traditional algorithms in terms of objective quality metrics, indicating good performance in image fusion applications.

The Co-Pilot Position of Vehicle Noise Quality Prediction Based on SVM

In three different types of domestic cars for example, the paper studied interior noise sound quality when engine idle at a constant speed in different speed operation. Noise test using HEAD Acoustics multi-channel noise test system, sound quality subjective evaluation experiment was carried out in a semi-anechoic. Vehicle sound quality was studied using support vector machine (SVM) model, the results showed that car interior sound quality mainly by four psycho-acoustical parameters: A-weighted sound pressure level, loudness, roughness and jitter degree. The support vector machine forecasting method can guarantee the accuracy of prediction results for small sample data, which has higher accuracy in predicting, error lower.

Cognitive effect on image quality in full ultra-high definition(8 K)

ABSTRACTResolution for displays are increasing from 4K-UHD to 8K-Full UHD. We conducted a subjective image quality evaluation to compare the image quality between 4 and 8 K by using diverse image stimuli. As a result, we identified perceptual and cognitive characteristics that can be demonstrated in image quality above 8 K. Cognitive and synesthetic factors as well as perceptual factors, and color expression were improved in 8 K image quality. The research findings suggested that both perceptual and cognitive factors are reinforced in 8 K. This tendency was even more reinforced when the main object was placed within the image. Also, the contrast and vividness felt higher at 8 K, of which the vividness influenced the cognitive evaluation of the 8 K image quality. When compared with 4 K, the image quality above 8 K was accompanied by optical illusion, which in turn improved the understanding of the main object. These results suggest that cognitive evaluations for a comprehensive understanding of images may be strengthened at a very high resolution of 8 K or higher beyond the ‘presence’ of 4 K resolution.

A Cross-Sectional Study of the Associations between Chronotype, Social Jetlag and Subjective Sleep Quality in Healthy Adults.

Social jetlag, a mismatch between internal biological time and social schedules, and a later timing of the midpoint of sleep on work-free days as an indicator of the circadian phase of entrainment (late chronotype), may be factors associated with poor quality sleep. This study examined the association of social jetlag and chronotype with subjective sleep quality ratings in a healthy young adult cohort and interrogated the moderating effects of sex and age on these associations. A total of 1322 participants aged 18 to 40 completed the Pittsburg Sleep Quality Index (PSQI) and the Munich Chronotype Questionnaire. Later timing of midsleep on “free” days (an indicator of chronotype) had a small-to-medium association with poorer subjective sleep quality, independently of sex and age (rho = 0.212, P < 0.001). Greater social jetlag had a small association with poorer subjective sleep quality ratings (rho = 0.077), and this effect was moderated by sex with there being a relationship between social jetlag and sleep quality only in males. Social jetlag did not mediate the relationship between chronotype and sleep quality. These results indicate differential relationships of the chronotype and social jetlag with subjective sleep quality and indicate that sex is a moderating factor for sleep quality’s relationship with social jetlag, but not for the association between sleep quality and chronotype.

Evaluation of the influence of the therapy with fosinopril and zofenopril on the regulatory-adaptive status of patients with diastolic chronic heart failure

Aim. Еvaluate the influence of combination therapy with fosinopril or zofenopril on the regulatory-adaptive status (RAS) of patients with diastolic chronic heart failure (CHF). Material and methods. The study includes 80 patients with CHF I-II functional class according to the classification of the New York heart Association with left ventricle ejection fraction ≥50% because of hypertensive disease (HD) of III stage, who were randomized into two groups for treatment with fosinopril (14.7±4.2 mg/day, n=40) or zofenopril (22.5±7.5 mg/day, n=40). As part of combination pharmacotherapy, patients were included nebivolol (7.1±2.0 mg/day and 6.8±1.9 mg/day), in the presence of indications, atorvastatin and acetylsalicylic acid in the intestinal shell were prescribed. Initially and after six months, the following was done: a quantitative evaluation of the RAS (by cardio-respiratory synchronism test), echocardiography, tredmil-test, six-minute walking test, determination of the N-terminal precursor of the natriuretic brain peptide level in blood plasma and subjective evaluation of quality of life. Results. Therapy, using fosinopril, in comparison with zofenopril, more improved RAS (by 66.5%, p

SPCM: Image quality assessment based on symmetry phase congruency

Phase congruency (PC) algorithm is a frequency based algorithm. Instead of processing image spatially, the PC algorithm calculates the phase and amplitude of individual frequency components in the frequency domain. As one of the successful algorithm of image feature detection, PC has some advantages in the image quality assessment, however it has some inherent limitations. This paper studies the applications of symmetry phase in image quality assessment (IQA) and proposes a metric based on symmetry phase congruency (SPC). Symmetry phase congruency overcomes the limitations of phase congruency during the feature detection of image. This paper proposes a new IQA metric which is named as the symmetry phase congruency metric (SPCM). The sign responses of neighboring pixels are used to find the location of symmetry phases and then the symmetry phase congruency is used to detect image features and assess image quality. The experimental results show that SPCM is more sensitive to structural features of image and more robust to noises, and SPCM can achieve a higher consistency with the subjective evaluation of image quality.

Magnetic resonance imaging and computed tomography of equine cheek teeth and adjacent structures: comparative study of image quality in horses in vivo, post-mortem and frozen-thawed

BackgroundThe use of cadavers for radiology research methodologies involving subjective image quality evaluation of anatomical criteria is well-documented. The purpose of this method comparison study was to evaluate the image quality of dental and adjacent structures in computed tomography (CT) and high-field (3 T) magnetic resonance (MR) images in cadaveric heads, based on an objective four-point rating scale. Whilst CT is a well-established technique, MR imaging (MRI) is rarely used for equine dental diagnostics. The use of a grading system in this study allowed an objective assessment of CT and MRI advantages in portraying equine cheek teeth. As imaging is commonly performed with cadaveric or frozen and thawed heads for dental research investigations, the second objective was to quantify the impact of the specimens’ conditions (in vivo, post-mortem, frozen-thawed) on the image quality in CT and MRI.ResultsThe CT and MR images of nine horses, focused on the maxillary premolar 08s and molar 09s, were acquired post-mortem (Group A). Three observers scored the dental and adjacent tissues. Results showed that MR sequences gave an excellent depiction of endo- and periodontal structures, whereas CT produced high-quality images of the hard tooth and bony tissues. Additional CT and MRI was performed in vivo (Group B) and frozen-thawed (Group C) in three of these nine horses to specify the condition of the best specimens for further research. Assessing the impact of the specimens’ conditions on image quality, specific soft tissues of the maxillary 08s and 09s including adjacent structures (pulps, mucosa of the maxillary sinuses, periodontal ligament, soft tissue inside the infraorbital canal) were graded in group B and C and analysed for significant differences within CT and MR modalities in comparison to group A. Results showed that MRI scores in vivo were superior to the post-mortem and frozen-thawed condition.ConclusionsOn comparing the imaging performance of CT and MRI, both techniques show a huge potential for application in equine dentistry. Further studies are needed to assess the clinical suitability of MRI. For further research investigations it must be considered, that the best MR image quality is provided in live horses.

Effects of hearing loss and language proficiency on speech intelligibility over radio transmission with tactical communication devices

Objective: Study the effects of hearing loss and language proficiency in a speech task over radio transmission.Design: Four TCAPS device conditions (2 models × 2 talk-through modes) were investigated with the Modified Rhyme Test (MRT) conducted in talker-listener pairs immersed in 85-dBA noise. Speech quality ratings and preferred radio volume levels were also collected.Study sample: Thirty-six participants divided into three groups (control, non-fluent, hearing-impaired) took part in the experiment. Participants acted as talkers and listeners when paired with a unique standard individual (fluent and normal hearing) of the same gender.Results: MRT scores were significantly lower in many device conditions when the non-fluent group of participants acted as listeners and talkers and when the hearing-impaired participants acted as listeners, compared to the control group. MRT results were also consistently poorer with one device configured for bone-conducted voice pick-up in the occluded ear compared to another one equipped with an external mouth microphone. Talk-through settings had little effect. MRT results were reflected in the subjective quality ratings. Participants with hearing loss used higher radio volume levels.Conclusions: Language proficiency, hearing loss and method of sensing the talker’s voice are key issues to consider with TCAPS devices.

Sperm kinematics and morphometric subpopulations analysis with CASA systems: a review

Sperm kinematics and morphometric subpopulations analysis with CASA systems: a review. The subjective evaluation of seminal quality has given way to the use of objective assessment techniques by CASA technology (computer-assisted semen analysis). The application of principal components (PC) and clustering methods to reveal subpopulations of spermatozoa is a powerful tool to evaluate raw semen and processed cell suspensions, but not many researchers are aware of the technique. PC analysis is a multivariate statistical method that reduces the number of variables used in subsequent calculations used to describe the data. By integrating the original variables according to their coherence in a database into a new complex mathematical variable, clearly defined homogenous subpopulations of spermatozoa can be defined. Kinematic, morphometric, morphological or DNA integrity tests may apply to characterize it and understand the reproductive biology of the spermatozoon. In recent years there has been a substantive change in the conceptual paradigm regarding what an ejaculate is. It should be said that until recently it was considered that the representative population (billions) of sperm was made up of "equivalent" cells with a common goal: to be the one that could finally fertilize the oocyte. The verification that the set of spermatozoa is grouped in distinct subpopulations, according to their kinematic and morphometric characteristics, opens the way towards a more cooperative vision. Besides, we have seen that the subpopulation distribution is different among males, which seems to indicate different strategies that can be understood within another paradigm, that of sperm competition between different ejaculates. The existence of heterogeneous subpopulations of spermatozoa in the ejaculate that show kinematics and morphometric patterns is widely known but the biological meaning of these different sperm subpopulations is still not clear. Although the role of the different subpopulations remains unknown, the work should continue in that direction.

No-Reference Quality Assessment of Stereoscopic Videos With Inter-Frame Cross on a Content-Rich Database

With the wide application of stereoscopic video technology, the quality of stereoscopic video has attracted people’s attention. Objective stereoscopic video quality assessment (SVQA) is highly challenging, but essential, particularly the no-reference (NR) SVQA method, where reference information is not needed and a large number of samples are required for training and testing sets. However, as far as we know, there are only a few samples in the established stereo video database, which is unsuitable for NR quality assessment and seriously hampers the development of NR-SVQA method. For these difficulties that we encountered, we carry out a comprehensive subjective evaluation of stereoscopic video quality in our newly established TJU-SVQA databases that contain various contents, mixed resolution coding and symmetrically/asymmetrically distorted stereoscopic videos. Furthermore, we propose a new inter-frame cross map to predict the objective quality scores. We compare and analyze the performance of several state-of-the-art 2D and 3D quality evaluation methods on our new databases. The experimental results on our established databases and a public database demonstrate that the proposed method can robustly predict the quality of stereoscopic videos.

Novel single-use duodenoscope compared with 3 models of reusable duodenoscopes for ERCP: a randomized bench-model comparison

Multidrug-resistant infectious outbreaks associated with duodenoscope reuse have been documented internationally. A single-use endoscope could eliminate exogenous patient-to-patient infection associated with ERCP. We conducted a comparative bench simulation study of a new single-use and 3 models of reusable duodenoscopes on a synthetic anatomic bench model. Four ERCP tasks were performed: guidewire locking (single-use and 1 reusable duodenoscope only), plastic stent placement and removal, metal stent placement and removal, and basket sweeping. The study schedule included block randomization by 4 duodenoscopes, 4 tasks, and 2 anatomic model ERCP stations. Ability to complete tasks, task completion times, and subjective ratings of overall performance, navigation/pushability, tip control, and image quality on a scale of 1 (worst) to 10 (best) were compared among duodenoscopes. All 4 ERCP tasks (total 14 subtasks) were completed by 6 expert endoscopists using all 4 duodenoscopes, with similar task completion times (median, 1.5-8.0 minutes per task) and overall performance ratings by task (median, 8.0-10.0). Navigation/pushability ratings were lower for the single-use duodenoscope than for the 3 reusable duodenoscopes (median, 8.0, 10.0, 9.0, and 9.0, respectively; P< .01). Tip control ratings were similar among all the duodenoscopes (median, 9.0-10.0; P= .77). Image quality ratings were lower for 1 reusable duodenoscope compared with the single-use and other 2 reusable duodenoscopes (median, 8.0, 9.0, 9.0, and 9.0, respectively; P< .01). A new single-use duodenoscope was used to simulate 4 ERCP tasks in an anatomic model, with performance ratings and completion times comparable with 3 models of reusable duodenoscopes.