Visible light communication based intelligent transportation systems (ITS-VLC) show great potential for future urban mobility. This study presents a performance evaluation of range estimation between ...vehicles and infrastructures in an ITS-VLC system. In the proposed ITS-VLC system, it is easy to simultaneously conduct communication and ranging using stereo cameras. However, the stereo camera calibration becomes a problem during simultaneous communication and ranging due to vehicle vibration. Using the data from LED transmitters and stereo cameras, it can obtain multiple measurements of distance. The monocular-stereo fusion algorithm is applied to visible light ranging in the proposed scheme using particle swarm optimization. We employed real data from the field trial experiment and achieved a ranging accuracy of 60 ± 1.0 m.
Neighboring views must be highly correlated in multiview video systems. We should therefore use various neighboring views to efficiently compress videos. There are many approaches to doing this. ...However, most of these treat pictures of other views in the same way as they treat pictures of the current view, i.e., pictures of other views are used as reference pictures (inter-view prediction). We introduce two approaches to improving compression efficiency in this paper. The first is by synthesizing pictures at a given time and a given position by using view interpolation and using them as reference pictures (view-interpolation prediction). In other words, we tried to compensate for geometry to obtain precise predictions. The second approach is to correct the luminance and chrominance of other views by using lookup tables to compensate for photoelectric variations in individual cameras. We implemented these ideas in H.264/AVC with inter-view prediction and confirmed that they worked well. The experimental results revealed that these ideas can reduce the number of generated bits by approximately 15% without loss of PSNR.
This paper aims to the improve the data rate for the visible light communication system using LED array and high-speed camera. Previously, we have proposed the decoding algorithm using inverted ...signals for driving situation. However, using this method the data rate become a half, because we transmit original signals and inverted signals alternately for LED array tracking. In this paper, we propose the data rate improving method for overlay coding which is coding method that overlay two data which are called as the long range data and the short range data. In the proposed method, for the long range data, we transmit original signals and inverted signals alternately. On the other hand, for the short range data, we transmit only original signals while we transmit inverted signals of long range data. We confirm that we can improve data rate as compared with the previous method.
Multiple-camera systems are emerging gradually.In order to let audiences feel comfortable when cameras are switched or when a free viewpoint video generated is shown,colour correction between cameras ...is necessary.Colour correction has usually two steps; the first step is to adjust camera parameters such as gain,brightness and aperture before capturing,and the second step is to modify captured videos by image processing.This paper deals with the latter step,which does not need a colour pattern board to be prepared,uses SIFT(Scale Invariant Feature Transform) to detect correspondences for occlusion handling,treats RGB channels independently,and transforms the distorted videos with a non-linear function.Our experimental results show that there was a better correlation between the corrected videos than that between captured ones.
In-vehicle cameras can be used as receivers for visible light communication in addition to their primary functions: for viewing assistance and object recognition. Most studies with this design ...perform tests via a single high-speed camera that is used as the receiver, but this study employs a receiver that uses a high- speed stereo camera. The reception method developed in this paper effectively utilizes left and right stereo images to improve communication performance. Although the selective diversity reception method proposed in previous work improved communication performance, it cannot deal with cases wherein both the left and right cameras introduce errors. To further improve the communication performance of this system, maximal ratio combining (MRC) diversity is applied to the high-speed stereo camera in this study. Communication performance is then evaluated comparing to the selective diversity reception and conventional single-camera reception by experimental tests conducted under static and driving conditions.
The present paper proposes a novel multiple-LED-arrays acquisition for an infrastructure-to-vehicle visible light communication (I2V-VLC) using LED arrays (transmitter) and an in-vehicle high-speed ...image sensor (receiver). In order to achieve a robust detection of LED arrays, we employ the block matching algorithm, which is a way of finding a corresponding position between two successive frames. The proposed method divides a captured image into a number of small domains (blocks) and determines if the LED array is present or absent using the block matching. We perform I2V-VLC experiments with multiple-LED arrays and evaluate the acquisition capability of the proposed method.
Visible light communication (VLC) is a wireless communication technology that employs visible light as a communication medium. Image-sensor-based VLC is suitable for multi-channel communication ...because multiple transmitters can be captured concurrently. In this paper, we propose a communication method for image-sensor-based VLC using multiple frames, which are intended to aid the simultaneous measurement of a multi-channel biological signal. The proposed method estimates the phase difference between the transmitter and the receiver using multiple frames shot at different timings compared to LED blinking, and communication is established through phase shift keying. Moreover, the proposed method is resistant to phase differences between the transmitter and the receiver, which is unavoidable in asynchronous communication. Through experiments, we confirmed that communication is possible using our proposed method.
In this paper, we discuss on a decoding algorithm for visible light communication systems in the driving situation using an LED array transmitter and a high-speed camera receiver. We propose an LED ...array detection method using M-sequence and an LED array tracking method using inverted signals. We confirm that we can distinguish LED array candidates correctly with M-sequence. We also confirm that we can suppress the flicker of the LED and improve the data rate as compared with the previous method.
Light-emitting diodes (LEDs) can add visible light communication (VLC) by high-speed blinking to their original lighting function. VLC using image sensors as receivers is referred to as image sensor ...communication (ISC). ISC eliminates noise and interference and enables multiple and simultaneous communication; hence it is suitable for outdoor mobile environments such as intelligent transport systems (ITSs). On the other hand, since the communication rate depends on the frame rate, it is difficult to increase. Therefore, the purpose of this study is to increase the communication rate by multilevel pulse width modulation (PWM). When the modulation level is increased, demodulation becomes difficult due to the bit per pixel (bpp) limitation of the image sensor. First, in order to perform efficient luminance extraction in limited bpp, we compare the maximum luminance extraction and the average luminance extraction. Then, we propose improving the nonlinearity between the transmitter and receiver, which is a problem in average luminance extraction suitable for a mobile environment, by applying precoded PWM. Finally, we evaluate effectiveness of precoded PWM experimentally.
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