Color Breakup Research Articles

90‐4: Field Sequential Color Micro‐LCD Enabling High‐resolution Light Field Displays

We report a light field display using a field sequential color (FSC) LCD based on mini‐LEDs. A newly designed panel with fast response triples the resolution by removing color filters. The color breakup is addressed by a deep learning‐based real‐time 3‐field driving method. Also, an elemental image rendering algorithm with extremely light computations is proposed.

BiPMAP: a toolbox for predicting perceived motion artifacts on modern displays.

Viewers of digital displays often experience motion artifacts (e.g., flicker, judder, edge banding, motion blur, color breakup, depth distortion) when presented with dynamic scenes. We developed an interactive software tool for display designers that predicts how a viewer perceives motion artifacts for a variety of stimulus, display, and viewing parameters: the Binocular Perceived Motion Artifact Predictor (BiPMAP). The tool enables the user to specify numerous stimulus, display, and viewing parameters. It implements a model of human spatiotemporal contrast sensitivity in order to determine which artifacts will be seen by a viewer and which will not. The tool visualizes the perceptual effects of discrete space-time sampling on the display by presenting side by side the expected perception when the stimulus is continuous compared to when the same stimulus is presented with the spatial and temporal parameters of a prototype display.

Deep learning-based real-time driving for 3-field sequential color displays with low color breakup and high fidelity.

Field sequential color liquid crystal displays (FSC-LCDs) are promising for applications needing high brightness and high resolution because removing color filters brings three times the light efficiency and spatial resolution. In particular, the emerging mini-LED backlight introduces compact volume and high contrast. However, the color breakup severely deteriorates FSC-LCDs. Concerning color breakup, various 4-field driving algorithms have been proposed at the cost of an additional field. In contrast, although 3-field driving is more desired due to fewer fields used, few 3-field methods that can balance image fidelity and color breakup for diverse image content have been proposed. To develop the desired 3-field algorithm, we first derive the backlight signal of one multi-color field using multi-objective optimization (MOO), which achieves a Pareto optimality between color breakup and distortion. Next, considering the slow MOO, the MOO-generated backlight data forms a training set to train a lightweight backlight generation neural network (LBGNN), which can produce a Pareto optimal backlight in real-time (2.3 ms on GeForce RTX 3060). As a result, objective evaluation demonstrates a reduction of 21% in color breakup compared with currently the best algorithm in color breakup suppression. Meantime, the proposed algorithm controls the distortion within the just noticeable difference (JND), successfully addressing the conventional dilemma between color breakup and distortion for 3-field driving. Finally, experiments with subjective evaluation further validate the proposed method by matching the objective evaluation.

65‐1: Deep Learning‐Enabled Image Content Adaptive Driving Algorithm for Field Sequential Color LCDs with Mini‐LED Backlight

We propose a driving algorithm for field sequential color (FSC) LCDs with a mini‐LED backlight. The algorithm adapts to image content through deep learning‐based image classification performed in each image segment, ensuring minimized color breakup in all segments. The mini‐LED FSC‐LCD having low color breakup for arbitrary images well satisfies applications needing high resolution and low power consumption.

75‐3: Field Sequential Color Displays with Simultaneously Suppressed Color Breakup and Flicker Based on Multi‐Objective Optimization

We propose a driving method for field sequential color displays, which simultaneously considers color breakup (CBU and flicker using multi‐objective optimization. We achieve the Pareto optimality. The CBU‐priority and flicker‐priority solutions, respectively, surpass all reference methods in CBU and flicker suppression. The balanced solution simultaneously suppresses CBU and flicker better than the reference methods.

Deep learning-enabled image content-adaptive field sequential color LCDs with mini-LED backlight.

The mini-LED as the backlight of field sequential color LCD (FSC-LCD) enables high contrast, thin volume, and theoretically tripled light efficiency and resolution. However, color breakup (CBU) induced by a relative speed between an observer and the display severely limits the application of FSC-LCDs. Several driving algorithms have been proposed for CBU suppression, but their performance depends on image content. Moreover, their performance plateaus with increasing image segment number, preventing taking advantage of the massive segments introduced by mini-LEDs. Therefore, this study proposes an image content-adaptive driving algorithm for mini-LED FSC-LCDs. Deep learning-based image classification accurately determines the best FSC algorithm with the lowest CBU. In addition, the algorithm is heterogeneous that the image classification is independently performed in each segment, guaranteeing minimized CBU in all segments. We perform objective and subjective validation. Compared with the currently best algorithm, the proposed algorithm improves the performance in suppressing CBU by more than 20% using two evaluation metrics, supported by experiment-based subjective evaluation. Mini-LED FSC-LCDs driven by the proposed algorithm with outstanding CBU suppression can be ideal for display systems requiring high brightness and high resolution, such as head-up displays, virtual reality, and augmented reality displays.

Chromatic aberration correction in bi-focal augmented reality display by the multi-layer Pancharatnam-Berry phase lens.

Chromatic aberration is a main obstacle for the commercial application of augmented reality displays. The current digital and optical compensation methods of reducing the chromatic aberration suffer from processing time, power consumption or complex design. Here, a simple strategy of chromatic aberration correction in bi-focal augmented reality near-eye display based on multi-layer Pancharatnam-Berry phase lens has been demonstrated and verified by experimental results. The multi-layer Pancharatnam-Berry phase lens, as a part of optical combiner, is fabricated by three liquid crystal polymer phase lenses with central wavelength in red, green, and blue, respectively. The multi-layer Pancharatnam-Berry phase lens can effectively reduce the chromatic aberration in both convex and concave mode of bi-focal augmented reality system, where the color breakup of virtual images captured in bi-focal augmented reality display is significantly alleviated. Comparing to the value of ΔK = 1.3 m-1 in single green Pancharatnam-Berry phase lens, the multi-layer Pancharatnam-Berry phase lens system significantly reduce the ΔK to 0.45 m-1 with reduction of 65.4%, which finally decreases the longitudinal chromatic aberration and improve the quality of images. The proposed broadband multi-layer Pancharatnam-Berry phase lens can benefit augmented reality displays and find widespread application in the near-eye displays.

SID: Powering the Display Industry for 60 Years

SID: Powering the Display Industry for 60 Years

Pre-compensation method for optimizing recording process of holographic optical element lenses with spherical wave reconstruction.

We propose a pre-compensated recording process of holographic optical element (HOE) lenses, where both of reference and signal waves have spherical wavefronts, for solving a wavelength mismatch problem between the recording and displaying process. Based on a localized approximation for aperiodic volume gratings, the wavelength mismatch and shrinkage effects are pre-compensated by optimizing the recording setup of HOE lenses, so that the Bragg condition of each local grating is satisfied. In order to realize the practical implementations of recording setup, complicated wavefronts to be required for the wavelength and shrinkage compensation are approximated into spherical waves. The simulation results using the volume hologram models of OpticStudio verify that the undesirable focal shift and color breakup problems in the HOE lens due to the wavelength mismatch are compensated. Displaying experiments using a full-color HOE lens with the field of view of 30° are presented, where the maximum wavelength mismatch between the recording and displaying process is 17 nm.

40‐4: Cost‐Efficient Polymer Flat Lens for Chromatic Aberration Correction in Virtual Reality Displays

An optical chromatic aberration correction method for virtual reality displays is demonstrated. With a cost‐efficient ultra‐broadband liquid crystal flat lens based on the Pancharatnam‐Berry phase, the proposed method can reduce the lateral color breakup by more than 10 times. Both simulation and experimental results are presented and discussed.

2.2: Invited Paper: Towards Picture‐Level Color Breakup Assessment for Sequential Color Displays

Considering color breakup assessment is important to sequential color displays, we review a series of work by classifying into threshold display configurations, metrics for special patterns, and picture‐level metrics. Next, we propose a general picture‐level metric by modeling the color‐breakup‐related visual attention with a new theorem of dominant visual saliency.

Resolution-enhanced light field displays by recombining subpixels across elemental images.

Light field displays based on integral imaging feature ultra-compact volume and freedom of the vergence-accommodation conflict for advanced virtual reality and augmented reality devices; however, they currently suffer from low visual resolution. Considering that subpixels have an intrinsically tripled resolution compared with triad pixels, this Letter develops a subpixel-level algorithm by recombining subpixels with relatively small raytracing errors from different elemental images. As a result, based on a highly accurate image formation model, the resolution of a typical system (pixel size, 7.8μm; system thickness, 4.07mm) is remarkably enhanced from 8.3 to 20.0 pixels per degree, for a gain of 2.41. In addition, the color breakup introduced by the chromatic subpixels is largely suppressed.

A Review of Color Breakup Assessment for Field Sequential Color Display

AbstractAssessing color breakup is a prevalent and intrinsic issue in field sequential color displays. Here, the authors review selected works on the topic, including studies on threshold display configurations for perceptible color breakup, metrics for special patterns, and metrics for natural images with varying contents.

I Know the Way to San Jose

Each time Display Week comes back to San Jose, I can’t help recalling the Dionne Warwick song (written by Burt Bacharach) “Do You Know the Way to San Jose,” about losing your dreams in LA and finding your way back home. It’s a bit of a metaphor for us because SID was originally founded in LA, and for a couple of decades that area was rich with display work. More recently, the Bay Area has been the home of many key display-related milestones and feels like the center of the industry, at least in North America. Display Week was last held in San Jose in 2015, and one of the biggest topics that year was OLED devices, materials, and displays. Quantum dots, microLEDs, and touch technology also claimed a lot of space in the program. Now, as we return in 2019, there continues to be much interest in OLED and microLEDs, but by far the biggest buzz is around augmented and virtual reality (AR/VR) display systems. It’s a field of research that seems to have exploded in the last few years, spurring all kinds of innovations and breathing new life into older topics, such as near-to-eye (NTE) displays. Just as you probably need to be a certain age to actually remember the San Jose song, you probably need to have some history in this business to remember that NTE displays were a focal point of research back in the early 2000s. The displays were good then, but not good enough. In the intervening years, a lot of supporting tech such as micro-processors and software have evolved to enable a new generation of devices that now have a compelling application named AR/VR to pull them into the marketplace. To get a handle on all that is coming this year at Display Week, please read “A First Look at Display Week 2019” (page 26) and start making your travel plans. This month, we also have the distinct privilege of announcing the winners of the 2019 SID Honors and Awards, which recognize professionals whose contributions or technical achievements have helped to advance the field of displays. This year’s honorees include a cross-section of great innovators whose contributions are like fingerprints that can be seen in many places and in many products today. Their stories are chronicled in “SID Salutes Industry Standouts” (page 21). Our issue theme is Applied Vision, and our guest editor Yi-Pai Huang, Ph.D., director of the Display Center at National Chiao Tung University (NCTU) in Taiwan, found us a great lineup of Frontline Technology features. It begins with “Temporal Requirements for VR Displays to Create a More Comfortable and Immersive Visual Experience,” an important discussion of the issues around temporal artifacts in head-mounted displays and opportunities to improve their performance, from Google researchers David M. Hoffman, Ph.D., and Grace Lee, Ph.D. Yi-Pai also brought us an in-depth story on the nature of color breakup assessment for field sequential color (FSC) displays by his NCTU colleagues Zong Qin, et al. FSC may be an emerging solution for high-performance NTE displays and, along with temporal artifacts, is a critical aspect of the user experience with AR and VR systems. We extend our heartfelt thanks to Yi-Pai for his hard work on this package, and don’t forget to read his guest editorial and introduction to these topics. Color and the science of color spaces are topics that regularly prompt questions and confusion from even deeply experienced display engineers. We were very pleased when Abhay Sharma, Ph.D., a professor at Ryerson University in Toronto, volunteered to do a series on this subject for our readers. His first installment, “Understanding RGB Color Spaces for Monitors, Projectors, and Televisions,” covers some very important ground, including color spaces for HDR displays. Abhay put in a lot of valuable hours on this article, pulling data from many sources and answering endless editorial questions from us along the way. We are very grateful for his time and I think you will benefit greatly from his efforts. There are many more wonderful elements to our issue this month and I hope you find them all enjoyable. Up next is our Display Week show issue in May, and with that I hope to see you all in San Jose.

Color breakup suppression based on global dimming for field sequential color displays using edge information in images.

Considering the high complexity of local dimming backlight that is necessary to effectively suppress color breakups for field sequential color liquid crystal displays (FSC-LCDs), a global dimming-based solution is proposed. This solution involves considering that the color breakups mainly occur at object edges of an image. By introducing an algorithm to present the edge information in a single field, evaluating color breakup performances, and experimentally verifying based on a 240-Hz LCD, lighter color breakups are revealed compared with mainstream local dimming-based solutions. Therefore, the proposed solution can achieve FSC-LCDs with better performance and practicality for advanced display applications.

Miniature holographic projector with cloud computing capability.

A fully functional miniaturized projection head below 5 cm3 is presented, using computer-generated holograms dynamically displayed on a liquid-crystal spatial light modulator. Spatial division of the modulator is used for color projection without color breakup, and specially designed, anti-reflection coated prisms ensure simple light paths with small losses. Real-time calculations are performed on a remote server with on-the-fly compression of holographic fringes. Cloud computing allows 1 W of local electrical power usage and apparent image brightness equivalent to 15-500 lm/W efficiency, depending on the displayed content. The properties of the projector allow future applications in handheld displays.

240Hz无滤色片液晶显示中色彩分裂现象的抑制

240Hz无滤色片液晶显示中色彩分裂现象的抑制

Effect of chemical preservatives on quality and storage condition of tomato puree

Tomato puree was prepared from tomato fruit of Roma cultivar with different concentration of chemical preservatives, packaged in plastic jars and stored at room temperature (32 ± 2 oC). The stored puree samples were analyzed with 15days intervals for physicochemical composition, sensory attributes and colour breakup. The aim of the research work was to investigate the effect of potassium meta bisulphite and sodium benzoate on tomato puree with addition of citric acid. The colour of TTP3 was very good showed at last analysis by Tintometer (Red: 22.9, Yellow: 7.1, Blue: 1.7). Statistical results revealed that TTP3 (sample treated with 0.05% Potassium meta bisulphite + 0.05% Sodium benzoate) was found best both physicochemically and sensory. The overall acceptability results showed less percent decrease in TTP3 (12.46%) followed by TTP1 (14.91%) and TTP6 (15.32%) respectively. The findings of statistical analysis also shows a significant effect (P <0.05) on treatments and storage of tomato puree. Keywords: Citric acid; Overall acceptance; Preservatives; Plastic bottles; Tintometer; Tomato puree http://dx.doi.org/10.19045/bspab.2018.70072

Image content adaptive color breakup index for field sequential color displays using a dominant visual saliency method

AbstractAn index that can predict the perceptual visibility of color breakup for varying image content is valuable in field sequential color displays, whereas the current indices are usually for fixed patterns. To solve this problem, an image database containing 25 diverse reference images and 125 test cases with various color breakup visibility was first established. Next, visual experiments using a 240‐Hz liquid crystal display were performed to acquire the subjective color breakup scores of the test cases. A theorem based on visual saliency theory was proposed that the color breakup perception is mainly determined by the image regions with visual saliency values higher than a certain threshold, called the dominant visual saliency regions. A computational model based on this theorem was developed to obtain objective color breakup scores of the test cases from retinal images with and without color breakup. An analysis of the objective and subjective results revealed a Pearson linear correlation coefficient as high as 0.82, which matches the top‐level image quality assessment algorithms. Finally, the proposed color breakup index was used to benchmark against several mainstream field sequential color algorithms to determine their performances in color breakup suppression.

Simulation of color breakup based on measured display temporal responses

AbstractBased on the measured temporal luminance behavior of each field, the perceived color breakup (CBU) artifact for moving block on a field sequential color display is simulated and predicted. The prediction accuracy is evaluated by a perceptual experiment on a 240 Hz liquid crystal display. The results show a perfect matching between the simulation and the subjects' actual visual experience. The simulation also works well when motion compensation is applied. It is validated by another perceptual experiment that a perfect or a near‐perfect compensation degree can suppress CBU significantly in field sequential color system. CBU of nature image was also simulated and reproduced for both stable and pulse backlight by using this model, which could be rather valuable for the further development of CBU metrics.