第三讲 图像信息处理

图像是人类传递信息的重要媒体,图像信息处理又是信息科学的重要研究分支.目前,起源于20世纪20年代的数学图像处理技术已成为工程学、计算机科学、信息科学、统计学、物理、化学、生物学、医学甚至社会科学等领域中各学科之间学习和研究的对象.文章全面综述了图像处理理论与技术的起源、涵盖的内容、对人类的重要意义及发展趋势.以期读者对图像信息处理有一个全面的理解.     

高铁座椅靠背压坏笔记本显示屏谁之过

乘坐高铁时,时有发生在小桌板上使用笔记本电脑时被前排座椅靠背压坏的事故,给双方乘客均造成了不必要的经济损失。本文首先介绍了一起发生在2022年3月4日的典型案例,然后利用力学理论分析了小桌板上笔记本显示屏被压破坏的原因,最后给出了高铁座椅和小桌板的优化设计建议,为避免类似事故再次发生提供了重要的借鉴。

     

3D Reconfigurable Vectorial Holography via a Dual-Layer Hybrid Metasurface Device

Metasurface-based vectorial holography manifests itself as an advanced platform for large-capacity information storage, holographic display, and cryptography. However, a convenient and effective reconfigurable vectorial hologram generation mechanism still remains a challenge. Here, a rotation-driven reconfigurable vectorial holography scheme is developed via a dual-layer hybrid metasurface device, in which radiation-type and birefringent metasurfaces are cascaded hybridly. Thus, reconfigurable and highly customizable intensity and polarization response of holograms in the 3D space is achieved. Rotatable radiation-type metasurface (RTM) serves as an incidence-wavefront modulator to excite the non-rotatable birefringent metasurface (BM). The gradient descent optimization inverse design method is introduced to achieve the high-efficiency reconstruction of the Jones vector and Jones matrix distribution on both RTM and BM. On this basis, numerical analysis and experimental verification of 3-D reconfigurable vectorial holography are demonstrated in the microwave region. This scheme implies a new paradigm for 3-D reconfigurable vectorial holography and can lead to advances in high-capacity optical display, switchable meta-devices, and cryptography.     

激光显示照明光路中复眼透镜的设计

设计激光投影机光学系统需要从如何减小光学系统的体积和提高激光光源的光效两个方面考虑。研究了激光显示照明系统中的复眼透镜,并对设计的复眼小透镜矩形单元进行了优化,发现在复眼透镜整体尺寸和单颗复眼小透镜焦距一定的情况下,整个复眼透镜上的阵列越多,即复眼透镜上蜂窝的数量越多,其匀光效果就越好,且此时投影机系统的体积也较小。为了提高激光光源的光效,设计中对复眼透镜在不同数值孔径照明光束下的匀光效果进行了讨论。并对优化设计后的复眼透镜进行40 000条光线追迹,实验显示其光线透过率可以达到92.5%,且几乎无杂散光。     

Curved Ferroelectric Liquid Crystal Matrix Displays Driven by Field-Sequential-Color and Active-Matrix Techniques

This paper describes a curved field-sequential-color matrix display using fast-response ferroelectric liquid crystal. Black matrix and transparent electrode patterns were formed on a thin plastic substrate by a transfer method from a glass substrate. While a composite film of liquid crystal and micro-polymers of walls and fibers was formed between the flexible substrates by printing, laminating and curing processes of a solution of monomers and liquid crystal, the mechanical stability was enhanced by use of multi-functional monomers to form large display panels. The image pixels of the matrix panel were driven by an active matrix scheme using an external switch transistor array at a frequency of 180 Hz for intermittent three-primary-color backlight illumination. The flexible A4-paper-sized color display with 24 × 16 pixels and 60 Hz field frequency was demonstrated by illuminating it with sequential three-primary-color lights from light-emitting diodes of the backlight. Our display system is useful in various information displays because of its freedom of setting and location.     

阵列像素器件投影显示系统中自动对焦评价函数研究

数字投影显示已成为现代数字显示领域的主流,阵列像素器件投影成像的的精确会聚,直接决定了显示的效果。阵列像素器件的自动对焦,是实现生产自动化的关键技术。以CCD(电荷耦合器件)采集阵列像素器件的局部投影图像为基础,试验和分析了梯度算子、拉普拉斯算子、Sobel算子、Prewitt算子、方差函数和熵函数评价方法在阵列像素器件大屏幕投影显示系统中自动对焦的作用及性能。实验表明,方差算子具有良好的稳定性和对噪声的不敏感性,调节效果较好,可以作为这一特殊系统中的评价方法。     

Hybrid diffractive-refractive 67°-diagonal field of view optical see-through head-mounted display

Design of a wide-angle off-axis optical see-through head-mounted display (HMD) becomes a challenge since its weight and size are constrained by human factors. Diffractive optics has the potential to play a key role in several areas of head-mounted display. They can reduce size and weight while providing some unique functions that would be difficult to implement with conventional refractive optics. This paper presents a 67°-diagonal field of view, wide spectral band hybrid diffractive-refractive see-through head-mounted display (HMD) using off-axis optics. It possesses a 10 mm exit pupil and a 22 mm eye relief, and satisfies the requirements of human factors. The whole optical system is suitable for a 20 mm-diagonal color liquid crystal display (LCD) with XGA resolution.     

高彩模式下的显示特技和兼容性技术

从显示的基本原理出发，对高彩模式下的显示特技和兼容性问题作了讨论，提出了显卡识别、虚拟显卡的实施方法，很好的解决了软件的兼容性问题，同时也大大提高了DOS环境下的图形界面的质量.     

Synthesis and characterization of crosslinked uniform polymeric microspheres containing a polyimide prepolymer by a new emulsification process

A highly crosslinked poly(styrene–divinyl benzene–trimethyolpropane trimethacrylate) microsphere containing a polyimide prepolymer (PIP) was prepared by a new emulsification method, Shirasu porous glass (SPG) membrane emulsification, and a subsequent radical suspension polymerization. That is, a mixture of styrene, divinyl benzene, trimethyol propane trimethacrylate (TMPTMA), and PIP containing an initiator was permeated through the uniform pores of the SPG membrane into a continuous phase containing a stabilizer to form uniform droplets. Then, the suspension polymerization was carried out at 65 °C for 24 h. The trifunctional crosslinker TMPTMA was added to enhance the destructive strength of the microsphere, and PIP was incorporated into the microsphere to provide an adhesion force by a known self‐curing reaction at 220 °C. The effects of the feed amounts of TMPTMA and PIP on the monomer conversion, size distribution, and destructive strength of the microsphere were investigated. The monomer conversion increased with an increase in TMPTMA. The particle size distribution became narrower as the TMPTMA feed amount increased, but it became broader with an increase in PIP. The destructive strength increased with increases in TMPTMA and PIP. After a heat treatment at 220 °C, the destructive strength decreased because of the heat degradation of the polymer. The addition of TMPTMA suppressed the heat degradation, and PIP could undergo self‐curing at 220 °C. The obtained highly crosslinked uniform microsphere containing PIP has potential applications in liquid‐crystal displays. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 2588–2598, 2003     

广角无限视景显示系统后投射屏的设计与研究

根据球面反射镜成像理论,利用改变光轴的方法,推导出了广角无限视景显示系统后投射屏面形的计算公式,完成了后投射屏最佳面形的设计。对后投射屏外表面散射层的材料和厚度进行了探讨,给出了最佳的选择方案。首次通过热吹模具成型法研制了高精度的整体投射屏。通过试验验证,该投射屏满足设计要求。使用该投射屏的广角无限显示系统具有图像清晰、视场角大、纵深感强等优点,同时观察者的视点还可在一定的出瞳范围内移动。