基於時域DPCM之即時倒車影像壓縮編碼法

Real-time Backup Video Compression Base on Time-domain DPCM

呂竣維(Chun-Wei Lu)

指導教授 ： 張陽郎

國立臺北科技大學/電資學院/電機工程系所/碩士(2010年)

摘要

為了行車的倒車安全，許多汽車都安裝了有線視頻後視系統，當車子倒車時，有線視頻後視系統就會將位於車子後側的影像，透過攝影機傳送至汽車前座的螢幕上，便可避免因為駕駛的視覺死角而導致的事故；目前一般市面上安裝的有線視頻後視系統，需要於汽車結構內佈線，對於尚未安裝後視系統的汽車而言，無線視頻後視系統更方便安裝。
然而在無線視頻系統技術上面臨兩個關鍵考量，(1)系統即時性和(2)頻寬限制，若是太複雜的壓縮編碼，會使系統運算時間增加，故兩者的平衡會是倒車視頻壓縮最重要的考量重點。
倒車影像屬全景移動影像且連續影像間相似度高，針對上述的特性，本研究提出以一個時域取代空間型式的誤差脈衝編碼調變編碼法(Differential Pulse Code Modulation, DPCM)，去除連續影像間的重覆資訊，並利用人眼對亮度與彩度變化的敏感程度高低，調整影像縮放參數，以符合目前最小規格通用型無線頻寬的6Mbps傳輸率。經研究證明此方法可以即時輸出影像，且影像可以維持一定的品質。

關鍵字

誤差脈衝編碼調變 ； 雙線性內插法 ； 雙立方內插法 ； 影像壓縮

並列摘要

For security of back-up driving, there are cars equipped with Wired Back-up Camera System. The system will transmit the image behind the car to the camera in front of the driving seat, when the car is in back-up mode. It could reduce accidents cause by the sight which can’t be seen by the driver.
However there are two key concern points about the Wire-less Back-up Camera System: real-time and bandwidth. If the coding is too complicate, it will lead to more compute time.
In this paper it will propose a time-domain method of Differential Pulse Code Modulation(DPCM) instead of the spatial method. Removing the continuing image, adjusting the scale factor, and considering the sense of human visual about luminance and chrominance integrate to meet with the least general standard of wireless bandwidth bit rate of 6Mbps.After research proves this method can both do real-time transmission and keep the quality of image.

並列關鍵字

DPCM ； Bi-linear interpolation ； Bi-cubic interpolation ； Image compression

參考文獻

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