| With the development of the information industry,TFTs and material technologies,which are core technologies of displays,have achieved rapid development.The recent developments in the field of displays satisfy the technical requirements of high resolution,high dynamic range(HDR),wide color gamut,and high frame rate,owing to the performance improvements arising from the use of TFTs and materials such as plastic boards and ITO.In terms of visual design and curved displays,which are the precursers of flexible displays,with functionalities suitable for curved surfaces,have already been commercialized,and are evolving into complete flexible displays.In this information age,the types of information reproduced on displays range from text oriented still images to graphic oriented moving pictures represented by videos and games.Therefore,the quality and performance of displays have a great influence on not only the legibility of the text but also the overall work performance in all aspects including information exchange and playing games.The evaluation of the quality and performance of consumer products such as displays should be user oriented;however,most evaluations of displays are mainly producer oriented.Therefore,to satisfy the needs of various consumers,it is necessary to change to an evaluation method that allows consumers to evaluate the products while using them in an actual user environment.Therefore,in the modern display design and production,especially for the advanced display technologies such as flexible display and high dynamic range display,it is of great significance to study the device performance from the perspective of human factors engineering through the aspects of perceptual image quality,visual work execution,visual fatigue,etc.Based on the new display technology,this paper comprehensively studies the influence of screen parameters such as display curvature,luminance and response time on human visual performance,visual fatigue,perceived image quality and other evaluation parameters,as well as the development of high dynamic range technology evaluation method and image processing research in high dynamic range technology based on human visual perceptual brightness.The main work and achievements of this paper can be summed up in the following five aspects:Firstly,the effects of the curvature of curved computer displays on the visual performance,fatigue,and emotional image quality were investigated based on the performance of visual tasks.The characteristics of curved displays were compared and analyzed for different curvatures to investigate whether the curved displays showed improvements in terms of convenience of use when compared to flat displays.The visual performance results for the evaluated displays can be classified into three groups according to their response times,as(2000R=2500R)>(3000R)>(3800R=4500R=Flat).The visual fatigue result for average pupil size during a search task was 3.468 mm for flat and 3.355 mm for 2000 R.This means that a 2000 R curved display was found to be easier to use and thus generated less visual fatigue than a flat display when performing the same visual search task.Further,the results indicated that visual performance improved and visual fatigue decreased significantly as curvature increased.In this study,a curvature limit of 1700 R was derived,when considering the image distortion of a 34-inch 21:9 curved display,and there was found to be no difference in the emotional image quality at curvatures greater than 2000 R.Secondly,according to the comparison between the brightness of peripheral vision and the stimulus on the cognition of brightness,the relationship between perceived brightness and the brightness of peripheral field of view was obtained.A lot of research work has been done before to enhance the perceived brightness of the display by improving the brightness of the display.However,studies have shown that the human visual system(HVS)is influenced not only by physical luminance,but also by other factors,such as adaptation to the surrounding luminance.Therefore,enhancing the maximum display luminance alone cannot be an optimal solution.The second study,we investigated the effects of the peripheral vision luminance(PVL)level and field of view(FOV)on the display brightness perceived by the observer,by using Stevens' brightness function,irrespective of the effect of adaptation to surround luminance.The analysis of the experimental results revealed that the perceived display brightness is inversely related to the level of peripheral vision luminance on the display.It was also found that,whereas increase in FOV results in an increase in the absolute brightness value,it reduces the effect of PVL on the perceived display brightness.The findings of this study will serve as useful basic data for optimizing display specifications with respect to image signals.Thirdly,the completion of visual work of moving images on different display screens was studied,and an effective ergonomic evaluation scheme was proposed.The effects of 4K organic light emitting diode(OLED)and liquid crystal display(LCD)TVs on human visual task performance and fatigue was compared when viewing moving pictures.In experiments conducted,subjects were asked to locate 35 icons among a total of 276 on screen icons at four moving picture speeds.From the results obtained,it was determined that OLED TVs(emissive type)exhibit superior characteristics for hit rate and false alarm rate compared to LCD TVs(Non emissive type).The evaluation results of a simulator sickness questionnaire administered to ascertain fatigue levels also indicated that OLED TVs induce relatively little fatigue at fast moving picture speeds of 10 ppf(pixel per frame)or more compared to LCD TVs.Thus,this study confirms that OLED TVs,given their ultra fast response time characteristics,are superior in terms of moving picture images to LCD TVs.Fourthly,the human perception of human characteristics was considered and the dynamic range of the display was suggested.Human eyes can perceive large light fields,but the existing standard dynamic range(SDR)is shown only through display showing a smaller range of values than humans actually seen.High dynamic range technology was developed to solve these problems.Therefore,it is imperative to use new methods to evaluate these techniques.It is important to evaluate the essence of dynamic range of high dynamic range.The proposed approach can contribute to the display of evaluation and standardization.This study proposes a new high dynamic range display evaluation method,which is recognized for its creativity and reproducibility.It was included in China's national electronic industry standards and IEC international standards in 2019.Finally,a video processing function that reflects the perception characteristics of human brightness was proposed.The existing image processing function uses the APL(Average Picture Level)to broaden the dynamic range of the input image.However,this method does not show application effects according to the gray scale distribution of images,or the problem of clipping occurs.Therefore,a function was proposed to efficiently expand the distribution of images to low and high gray level,thereby minimizing the saturation of the gray level.It was confirmed that the new function proposed by image rendering has a high image dynamic range and can be further extended to achieve not only a high dynamic range but also excellent low gray and color performance. |
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