| UAV(unmanned aerial vehicle)have become a priority in every modern society.Many countries attached the importance to the development of UAVs that is due principally to the broad range of their use,for both military and civilian purposes.One of most important use of the UAV is to achieve aerial surveillance and battlefield monitor.The information should be transmitted to the receive ground station in real time via a way of wireless transmission.the digital signal transmission have many advantages such us high quality,strong ability of keeping secret and strong anti-jamming ability,But the wireless channel,in general,exists certain problems,such as the great data quantity and limited bandwidth.In order to improve the efficiency of transmission and ensure the quality of image data received,the image data is needed to be deal with effective compression before wireless transmission.Because the UAV image has weak local correlation and the relativity between the pixels in the frame is little so the ordinary compress methods have some limit in some degree.Basing on the existing image and video coding standards,much research has been done in this paper.We adopted MATLAB to programme this thesis.For still image compression,an embedded-coding image compression algorithm based on wavelet transform is implemented.This image coding algorithm is achieve better compression than JPEG compression standard and is comparable to the JPEG2000 standard in the coding efficiency.In image sequence compression,based on the still image coding algorithm,a new UAV image sequence compression scheme is proposed in this paper.In the scheme by utilizing the characteristics of UAV image sequence,a motion estimation algorithm is introduced,it can deeply reduce the computational complexity,and greatly save the bit rate.The experiments show that this scheme has the low complexity coding and comparable with the H.264 standard in the compression performance. |
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