When watching stereoscopic three-dimensional (S3D) display, most people will feel visual discomfort due to the color asymmetry of left and right eyes. However, a stereo pair consisting of one gray image and one color image can be perceived by a human observer as a 3D color scene, and there is no depth perception degradation and only limited color degradation. This novel presentation approach of stereoscopic display can reduce the redundancy of color information, optimize the video compressions and greatly save the transmission bandwidth. And it may also alleviate the visual comfort problem of asymmetric color stereoscopic content by reducing the visual system load. In this paper, visual comfort was evaluated for stereoscopic videos with different gray-color allocation schemes. Three allocation schemes are used to investigate the changes of visual comfort of stereoscopic video. The subjective evaluation results show that different binocular color allocation schemes have an impact on the visual comfort assessment (VCA) scores. Among them, the binocular color coding of the left half of all frames in stereoscopic video are color and the right half of all frames are gray, which may reduce the amount of color information processing by the visual brain and therefor has a more comfortable visual experience. We suggested that the color allocation scheme also can reduce the flicker of video, and the visual comfort of stereoscopic contents with only half color information is We demonstrated that this color allocation scheme also can reduce the flicker of video, and the visual comfort of stereoscopic contents with only half color information is within the acceptable range.
KEYWORDS: 3D image processing, Eye, Image processing, 3D vision, Visual analytics, Stereoscopic displays, 3D displays, Image quality, Glasses, Human vision and color perception
With the rapid development of stereoscopic 3D (S3D)display technology, some problems have gradually emerged. Among them, the color information of the S3D image has a significant impact on the visual comfort of S3D content. In this paper, in order to obtain more information about the visual discomfort of hue asymmetries 3D images and to ensure the reliability of the experimental results, we adopted a subjective and objective method. In the subjective experiment, the subjects rated the 3D images according to their own visual perception when watching the hue asymmetric 3D images. Finally, we will get the subjective score corresponding to each 3D image to indicate the visual comfort of the stereoscopic image. The objective experiment means that when the subjects watch the 3D images, we will use the eye tracker to record the subjects' blink data. Statistical analysis of visual comfort scores and blink data shows that as the hue asymmetric level of the 3D image increases during the viewing of hue asymmetric 3D images, the more blinks and the longer the blinking time. The stronger the visual discomfort.
The spectral reflectivity of the visible light bands of a non-self-illuminating object is one of the root causes of the colour formation of an object, and its uniqueness can be used to distinguish objects. Under low illumination conditions, the ability of the visible light image sensor to capture the colour of an object is greatly reduced. However, the object still has near-infrared radiation. The near-infrared radiation of the object collected by the near-infrared image sensor is combined with the visible light information of the object to improve the colour quality of the acquired object. Since the spectral reflectivity information of an object requires professional equipment to collect, it is inconvenient to use. Aim to more convenient use of spectral information data for colour restoration under low illumination conditions. In this paper, a plant’s spectral reflectivity database in visible and near-infrared bands was proposed. Firstly, 50 plants samples such as ginkgo were collected from 400 nm to 1000 nm spectral reflectivity data by a full-bands hyperspectral sorter and processed by Minimum Noise Fraction (MNF). Secondly, according to the requirements of this database, the business process, function modules and architecture of the database are designed in detail. Finally, according to the design, use C# and SQL Server to establish the database. The establishment of this database provides some data support for colour restoration and other applications.
KEYWORDS: 3D displays, Eye, Visualization, Cones, Image processing, 3D image processing, Calibration, Colorimetry, Information technology, Color vision
As an important feature of image, color can be used to achieve binocular vision. However, different colors may have different contributions. In this experiment, we designed a stimulus in which luminance is incongruent and color could be manipulated. Color variations were based on opponent color space, where seventeen color points distributing in red-green and blue-yellow directions were selected. The stimulus consisted of an array of asymmetric patches uniformly distributed in a constant sized volume. Subjects were required to indicate the amount of perceived depth patches in the 3D displays. Our results demonstrate that the amount of perceived depth patches was influenced by color information, and indicate that colors have different contributions to binocular matching.
Image registration has always been the hot topic in image research field, and the mutual information registration method has become a commonly used method in image registration because of its high precision and good robustness. Unfortunately, it has a problem for infrared and visible image registration. Lots of rich background detail information is usually provided by the visible light band, while the infrared image can locate an object (heat source) with a higher temperature, and often can't obtain the background information. The large difference in the background information of the two images not only interferes with the accuracy of the registration algorithm but also brings a lot of computation. In this paper, a method of fuzzy c-means clustering is used to separate foreground and background which reduces the background information interference for registration, based on the feature that the infrared image and the visible image have a high uniformity in the target area and a large difference in the background area. Then, the mutual information of the foreground image marked by clustering algorithm is calculated as the similarity measure to achieve the purpose of registration. Finally, the algorithm is tested by the infrared and visible images acquired actually. The results show that the two image’s registration is perfectly implemented and verify the effectiveness of this method.
KEYWORDS: 3D displays, Visualization, Eye, Stereo holograms, Color vision, Lutetium, Autostereoscopic displays, Information science, Information technology, Brain
Stereoacuity, or named stereoscopic acuity, is the minimum disparity that can be perceived by someone with two eyes and normal brain functions. It is extremely relevant to human stereopsis and considerable individual variability. Due to the contribution of color information to stereopsis is controversial, this study is focused on designing and conducting a stereoacuity test for different colors. In particular, the effect of color variations on stereoacuity was evaluated by using 3D displays to present color random-dot stereogram (RDS) stimuli. Seventeen color points sampled from the CIELAB color space were selected for the test. All sample color points are averagely distributed in red-green and yellow-blue directions at isoluminance. The stimuli had the same dot density of 50% and black background, with different colors and disparities. Then the minimum disparity was obtained as the stereoacuity of subject. The results of experiment show that the stereoacuities are not significantly different in red-green direction and blue-yellow directions. These results support the view that color does not contribute to the stereoacuity.
KEYWORDS: Visualization, 3D displays, Eye, Color difference, Color vision, Image fusion, CRTs, Stereoscopic displays, RGB color model, Information technology
Color asymmetry is a common phenomenon in stereoscopic display system, which can cause visual fatigue or visual discomfort. When the color difference between the left and right eyes exceeds a threshold value, named binocular color fusion limit, color rivalry is said to occur. The most important information brought by stereoscopic displays is the depth perception produced by the disparity. As the stereo pair stimuli are presented separately to both eyes with disparities and those two monocular stimuli differ in color but share an iso-luminance polarity, it is possible for stereopsis and color rivalry to coexist. In this paper, we conducted an experiment to measure the color fusion limit for different disparity levels. In particular, it examines how the magnitude and sign of disparity affect the binocular color fusion limit that yields a fused, stable stereoscopic percept. The binocular color fusion limit was measured at five levels of disparities: 0, ±60, ±120 arc minutes for a sample color point which was selected from the 1976 CIE u'v' chromaticity diagram. The experimental results showed that fusion limit for the sample point varied with the level and sign of disparity. It was an interesting result that the fusion limit increased as the disparity decreases at crossed disparity direction (sign −), but there is almost no big change at uncrossed disparity direction (sign +). We found that color fusion was more difficult to achieve at the crossed disparity direction than at the uncrossed disparity direction.
Color asymmetry is a common phenomenon in 3D displays, which can cause serious visual discomfort. To ensure safe and comfortable stereo viewing, the color difference between the left and right eyes should not exceed a threshold value, named comfortable color difference limit (CCDL). In this paper, we have experimentally measured the CCDL for five sample color points which were selected from the 1976 CIE u'v' chromaticity diagram. By human observers viewing brief presentations of color asymmetry image pairs, a psychophysical experiment is conducted. As the color asymmetry image pairs, left and right circular patches are horizontally adjusted on image pixels with five levels of disparities: 0, ±60, ±120 arc minutes, along six color directions. The experimental results showed that CCDLs for each sample point varied with the level of disparity and color direction. The minimum of CCDL is 0.019Δu'v' , and the maximum of CCDL is 0.133 Δu'v'. The database collected in this study might help 3D system design and 3D content creation.
Illumination estimation is the main step in color constancy processing, also an important prerequisite for digital color image reproduction and many computer vision applications. In this paper, a method for estimating illuminant spectrum is investigated using a digital color camera and a color chart under the situation when the spectral reflectance of the chart is known. The method is based on measuring CIEXYZ of the chart using the camera. The first step of the method is to gain camera′s color correction matrix and gamma values by taking a photo of the chart under a standard illuminant. The second step is to take a photo of the chart under an estimated illuminant, and the camera′s inherent RGB values are converted to the standard sRGB values and further converted to CIEXYZ of the chart. Based on measured CIEXYZ and known spectral reflectance of the chart, the spectral power distribution (SPD) of the illuminant is estimated using the Wiener estimation and smoothing estimation. To evaluate the performance of the method quantitatively, the goodnessfitting coefficient (GFC) was used to measure the spectral match and the CIELAB color difference metric was used to evaluate the color match between color patches under the estimated and actual SPDs. The simulated experiment was carried to estimate CIE standard illuminant D50 and C using X-rite ColorChecker 24-color chart, the actual experiment was carried to estimate daylight and illuminant A using two consumergrade cameras and the chart, and the experiment results verified feasible of the investigated method.
KEYWORDS: Image quality, Gaussian filters, Video, Digital filtering, Detection and tracking algorithms, 3D image processing, Diamond, Image filtering, Signal to noise ratio, Televisions
Depth Image Based Rendering (DIBR) technology is one of effective methods to generate stereoscopic image pairs in 3D image warping, however, the holes would be produced when using this method. Hole-filling algorithms are essential for improving image quality of stereoscopic image pairs. In this paper, a new hole-filling algorithm based on pixel labeling is proposed. Firstly, holes in stereoscopic image pairs produced by DIBR are marked as 0, whereas marked as 1. Then traversing the image pairs only once to fill pixel values of each hole according to the situation of hole’s eight neighborhood pixels, the hole would be filled by the average of no-hole pixel values when the number of no-holes greater than threshold, otherwise the hole is filled by the cross diamond search algorithm from every direction to find the closest no-holes until the number of no-holes greater than threshold. The proposed method is evaluated by existing objective assessment methods, such as PSNR and SSIM. Experiment results show that the proposed hole-filling algorithm provides an improvement in both of subjective and objective assessment by compared with the conventional hole-filling algorithm under the same source images. The proposed algorithm is not only simple, but also can effectively eliminate the holes generated by using the DIBR method.
KEYWORDS: Visualization, Video, 3D displays, 3D vision, Stereoscopic displays, 3D visualizations, 3D metrology, Nickel, Color vision, Display technology
It is well known that some viewers experience visual discomfort when looking at stereoscopic displays. The disparity is
one of the key factors that affect visual comfort in 3D contents, and there is a comfortable disparity range for a person. In
this paper, we explore the comfort disparity, which correlates with the optimal viewing distance, as a function of the
maximum disparity for an individual. Firstly, the individual maximum disparities of 14 subjects were measured. Then
the subjects were asked to rate the comfort scores for a 3D video sequence with different disparity, to evaluate the
individual comfort disparity. The results show that as the individual maximum disparity increased, the corresponding
comfort disparity increased, and we found a correlation coefficient of r=0.946. The average ratio between the comfort
disparity and the maximum disparity was approximately 0.72, and this ratio can be used for one to determine the optimal
3D viewing distance by a rapid method.
KEYWORDS: 3D displays, Visualization, Cones, 3D image processing, Color vision, Stereo holograms, CIE 1931 color space, Colorimetry, LCDs, Optical engineering
The contribution of color information to stereopsis is controversial, and whether the stereoscopic depth perception varies with chromaticity is ambiguous. This study examined the changes in depth perception caused by hue variations. Based on the fact that a greater disparity range indicates more efficient stereoscopic perception, the effect of hue variations on depth perception was evaluated through the disparity range with random-dot stereogram stimuli. The disparity range was obtained by constant-stimulus method for eight chromaticity points sampled from the CIE 1931 chromaticity diagram. Eight sample points include four main color hues: red, yellow, green, and blue at two levels of chroma. The results show that the disparity range for the yellow hue is greater than the red hue, the latter being greater than the blue hue and the disparity range for green hue is smallest. We conclude that the perceived depth is not the same for different hues for a given size of disparity. We suggest that the stereoscopic depth perception can vary with chromaticity.
This paper provides a review of 3D display technology and a design of Near-Eye 3D Display (NE3D). In present, image
quality and visual comfort are the main problems of 3D display. We designed a NE3D with using the latest 0.5 inch
OLED microdisplay chips, and it contains dual-OLED and two freeform lenses, which provides the left- and right-eye
image of a side-by-side displayed stereo pair to the appropriate eye. It is a "free view" 3D display technology, and
interocular crosstalk was eliminated completely by using direction multiplex. Crosstalk is one of the largest contributing
factors to cause visual discomfort. The paper detailed the OLED microdisplay, and gave the parameters of optical
system for a compact head-mounted display. Some future works were also referred.
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