A remote sensing image fusion method based on the matting model is presented. The matting model refers to each band of the hyperspectral (HS) image that can be decomposed into three components, i.e., alpha channel, spectral foreground, and spectral background. First, the panchromatic (PAN) is sharpened to enhance the spatial details and the intensity component of the HS image is obtained by the nonlinear synthesis method. Different from the traditional matting model-based method in which the PAN image serves as the alpha channel, we subsequently transform the sharpened PAN image and the intensity component to the principal components analysis domain to obtain the first principal components channel. The first principal components channel is selected as the alpha channel of the HS image. The selected alpha channel contains most of the spatial information of both the PAN and HS images. Finally, the HS foreground and HS background are estimated by the alpha channel, and the fused HS image can be reconstructed perfectly. Experimental results reveal that the proposed method is superior to the existing state-of-the-art methods.
Optical fiber tweezers based on a graded-index multimode fiber (GIMMF) tip is proposed. Light propagation characteristics and gradient force distribution near the GIMMF tip are numerically investigated, which are further compared with that of optical fiber tips based on conventional single mode fibers. The simulated results indicated that by selecting optimal GIMMF length, the gradient force of the GIMMF tip tweezers is about 4 times higher than that of the SMF tip tweezers with a same shape. To prove the feasibility of such a new concept, optical trapping of yeast cells with a diameter of ~5 μm using the chemically-etched GIMMF tip is experimentally demonstrated and the trapping force is also calculated.
Novel fiber Bragg gratings (FBG) based settlement sensors are developed and the sensing performance is evaluated in
both the lab and field environments. The settlement is determined by precisely measuring the pressure of the water level
difference. The experimental results indicated that the sensor has good linearity, good repeatability and high accuracy in
the settlement measurements. The influence of temperature fluctuations on the sensor's performance is eliminated and
long-term test results proved the good stability of better than ±0.1% of the sensor. Such a FBG sensing system has been
applied to monitor the settlement of high-speed railways in practice.
Nowadays, throughputs, average path utilization and transmission efficiency are still the important factors which affect the
quality of satellite communication. Recently, MORE (MAC-independence Opportunistic Routing) protocol was put forward
to improve the throughput and transmission efficiency in ground wireless network. However, MORE is not appropriate for
satellites network because satellites available do not have the monitor ability which is necessary in MORE and it is also too
expensive to monitor in satellites. In this paper, an improved MORE protocol was proposed to apply to satellites, which is
called path scalable network coding (PSNC) protocol. The theoretical analysis reveals the feasibility and effectiveness of the
proposed algorithm. The simulation results show that the algorithm can effectively increase the average path utilization and
the innovative packet ratio over satellite networks.
Recently, providing reliable transmission over satellite networks is still a challenging problem due to the dynamic changes of the satellite topology, the large delay and the high error rate of the satellites’ links. The benefits of network coding are well understood to solve those problems above for a large class of wireless networks. In this paper, a new coding-aware routing algorithm is proposed to decrease the large delay and improve the transmission efficiency by performing network coding opportunistically instead of using network coding always or using the shortest path routing only. The theoretical analysis and simulation results show the correctness and effectiveness of the proposed algorithm.
Satellite communications have been rapidly developed due to its advantageous of wide coverage and large capacity.
However, an efficient and robust transmission scheme still needs carefully designed due to the time-varying and
unreliable nature of links of the satellite networks. In this paper, we consider cooperative communications by selecting
relays dynamically via setting an appropriate threshold according to the real-time channel conditions to avoid error
propagation and then apply opportunistic network coding (ONC) to further enhance network throughput. Considering the
sparse representation of natural images, block based compressive sensing (BCS) and the proposed ONC are combined in
a novel way forming an energy-efficient image processing system which is easy to be implemented. Simulation results
show that the scheme we proposed can gain better performances compared with traditional cooperative and network
coding methods.
In EDCA-based wireless networks, all video packets are identically mapped without differentiation into one of four
access categories to be transmitted so that the delivery performance is restricted. Even though some researches remapped
video packets by differentiating their significance according to packets types, they refrained from more gains since they
adopted a type of fixed significance model and mapping scheme. In this paper, a new model for video packet
significance is built and then a dynamically mapping algorithm based on the packet significance model is proposed to
improve the performance of video delivery over EDCA-based wireless networks. The proposed algorithm detects
periodically the available resources of each AC and makes full use of the all ACs to transmit video packets. Simulation
results demonstrate that the proposed algorithm improves performance of video delivery and increases the image quality.
Nowadays, providing reliable broadcast and multicast transmission over wireless networks is still a challenging problem,
due to the erratic and time-varying nature of a wireless channel. An efficient retransmission strategy is very important to
the reliability of transmission and the bandwidth utility of the wireless network. In this paper, an opportunistic network
coding retransmission algorithm based on packet loss pattern is proposed to improve the transmission efficiency of
broadcast and multicast over wireless networks. The theoretical analysis reveals the feasibility and effectiveness of the
proposed algorithm. The simulation results show that the algorithm can effectively reduce the retransmission times and
increase the transmission efficiency over wireless networks.
In order to improve the reconstructed quality of video sequence, a Random Linear Network Coding (RLNC) based video
transmission scheme for Scalable Video Coding (SVC) is proposed in wireless broadcast scenario. A packetization
model for SVC streaming is introduced to transmit the scalable bit streams conveniently, on the basis of which the
RLNC based Unequal Error Protection (RUEP) method is proposed to improve the efficiency of video transmission. The
RUEP's advantage lies in the fact that the redundancy protection of UEP can be efficiently determine by the capacity of
broadcast channel. Simulation results show that RUEP can improve the reconstructed quality of video sequence
compared with the traditional Store and Forward (SF) based transmission schemes.
KEYWORDS: Video, Scalable video coding, Video surveillance, Spatial resolution, Temporal resolution, Signal to noise ratio, 3D video streaming, Forward error correction, Receivers, Video coding
Nowadays, it is still a challenge to offer high quality and reliable real-time video services over wireless network. In this
paper, we studies a new practical scalable video coding (SVC) multicast scheme based on unequal error protection
(UEP) framework with priority transmission. Firstly, we propose a 3D layer-based priority ordering method to determine
the importance of scalable video bit stream. Then we present an adaptive packetization algorithm to allocate the source
and channel code bit rate for ordered layers and guarantee the layers with highest importance could be recovered first.
Simulation results show that the proposed scheme offer better performance than existing methods in preserving video
quality for different kinds of sequences under various channel conditions.
KEYWORDS: Video, Video coding, Video processing, Forward error correction, Computer programming, Motion estimation, Video compression, Computing systems, Telecommunications, Signal attenuation
A new multple description selection/separation method for transmission of video bit stream over wireless channel is proposed in this paper. The method inserts transition frames according to the relative motion between two neighboring frames, and then divided the video sequence into two descriptions with independent prediction loops. The experimental resulst show that the method can help the decorder more quickly recovered from single loss or burst loss compared with previous method, and provides more stable and better quality for the reconstruction of video sequence.
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