立体显示、虚拟现实及头戴设备的应用研究需要对人眼视觉双目特性做更深入的研究。阈值测量是研究视觉感知特性的方法之一，人的左右眼分别观看不同的颜色，且双眼观看的颜色色差不超过双目颜色融合的阈值时，可能会感知到灰色，也就是发生了双目色调消除现象。为了研究这种特殊现象，本文设计了视觉心理物理学实验，在CIELAB颜色空间中研究双目融合范围内能够感知到灰色现象的对立颜色方向和色差阈值，并将实验结果分别在LMS、Macleod-Boynton、DKL等颜色空间中表示，为进一步研究人眼特性及双目颜色机理提供实验数据。

运用彩色图像色调、饱和度、强度（HSI）模型的H分量进行彩色图像阈值分割是一个新的彩色图像阈值化方式。考虑到H分量是一个圆形直方图，将圆形直方图断开为线性直方图，然后采用线性直方图阈值分割法进行阈值选取是一种有效途径。在信息论中，信息能量是Shannon熵的对偶，首先引入线性概率分布的累积分布信息能量概念，基于此来确定圆形直方图的断点；然后给出线性直方图上的信息能量阈值法，并基于此实现H分量圆形直方图的阈值选取。相比于基于对数运算的Shannon熵阈值选取准则，基于平方运算的信息能量阈值选取准则具有表述简单、运算速度快的优点。

A psychophysical experiment under constant stimuli is conducted on a CRT display to measure the visual suprathreshold color differences for five color centers recommended by CIE under the same five background colors. The performances of four CIELAB-based, three CIECAM02-based, and two OSA-UCS-based formulas are tested. Detailed analysis results indicate the existence of chromatic crispening effect. CIEDE2000 performs best for the gray center and gray background, whereas CAM02-LCD and CAM02-UCS have the best performance for non-neutral backgrounds. CAM02-LCD significantly outperforms all other formulas for all color centers under all background colors.

Head-up displays (HUDs) enable a pilot to manage aircraft activities by facilitating simultaneous access to the flight instrument data and to the outside scene. However, HUDs can also distract a pilot. This study shows that HUD luminance non-uniformity may force inappropriate distribution of attention between the events shown on HUD symbology and the outside scene because of the resultant differential contrast in the display area. Results of statistical analysis demonstrate considerable effects of HUD image luminance and ambient luminance, as well as their interaction, on the detection of events displayed on an HUD and the outside scene.

This letter presents a label-free biomolecular imaging technique based on white-light interferometry and spectral detection. The method measures thickness changes caused by specific binding between biomolecules to detect the presence of certain analyte. A spectrum-shifting algorithm is developed to resolve the thickness information from the spectrum. The axial resolution of the experimental instrument can reach ～1 nm, thereby enabling detection of trace amounts (~1 ng/mm2) of proteins or DNA. This letter also presents two experiments to prove the feasibility of the method for detecting proteins and DNA without fluorescent labeling.

In this letter, a new single three-dimensional (3D) laser projector is proposed. As liquid crystal (LC) can produce two image patterns with orthogonal polarization states at 120 Hz, only one projector is required in this approach for reconstruction of a 3D object. The light source is made up of RGB (red, green, and blue) lasers because laser has lots of advantages such as longer life, higher brightness, and larger color gamut. A novel diffusive media with good polarization-maintaining quality is used as rear projection screen for its high transmission efficiency (～90%) and low reflection efficiency. When laser incidents into the diffusive media, which contains lots of spherical particles with sizes between 2 and 15 \mu m, laser is scattered randomly and the laser speckle is reduced. A spatial phase mask is also inserted into the optical path to reduce speckle. With these techniques, the speckle contrast is reduced to 0.1 and the quality of image patterns has been greatly improved.

A psychophysical experiment is carried out to evaluate the color difference between pairs of color digital images and their modulated versions, which are displayed on a professional liquid crystal display (LCD) monitor, using the category judgment method. The modulated images for six original images are generated with variations in five attributes, namely, lightness, chroma, hue, resolution, and sharpness, considering both their chromatic and spatial characteristics. Several color difference evaluation methods, namely, CIELAB, CIEDE2 000, CAM02-UCS, S-CIELAB, and iCAM, are compared based on the experimental data. The results demonstrate that the performance of iCAM is the best for predicting image color difference.

The design of a two-dimensional (2D) microscanner actuated electrostatically is presented, and a silicon-oninsulator (SOI) micromachining process is utilized to fabricate the sample. The microscanner can oscillate at inherent frequencies of 1146 and 360 Hz around two rotational axes, generating maximum twisting angles of ±10o and ±5.3o under two 10-V square waves, respectively. A monochromatic laser projection system based on Lissajous pattern is demonstrated using the developed microscanner, revealing an image resolution of 168 \times 56 at 20 frames per second.

For many years, various local feature descriptors have been proposed. Among them, Lowe's scale invariant feature transform (SIFT) descriptor is the most successful one and has been proven to be performed better n the distinctiveness and robustness than other descriptors. However, SIFT descriptor is based on gray level images and pays little attention to the color information which can be a powerful cue in the distinction and recognition of objects. To increase the discriminative power, color features have been plugged into the feature descriptors only recently. In this letter, we study the photometric invariant properties of the Lowe's SIFT, HueSIFT, rgSIFT and CSIFT based on color diagonal offset model. Theoretical and experimental results show that the four descriptors are not fully invariant to photometric transformation. To solve this problem, a new color invariant framework based on color diagonal offset model is proposed in this letter. Experimental results validate our proposed framework.