【发布时间】：2016-02-12 01:47:00
【问题描述】：
好的，所以我做了我的研究，这里有很多关于线程同步的问题，但没有一个真正切中要害。我目前在 Opencv 中工作，我从包含车辆的摄像头中获取一个帧，移除背景并跟踪车辆，但在此之前，我会进行一些预处理和后处理，例如通过模糊去除噪声，所有这些都运行一个线程，它工作得很好，但出现了一个问题，我现在想读取车牌，为此我需要一个更高分辨率的帧，否则对于每一帧我都不会检测到单个车牌，但是一旦我增加我的帧大小我的性能受到影响，我的线程速度变慢，以至于我的程序不再符合实时系统的条件。
所以我想在我的场景中添加更多线程，每个线程都专注于一项任务 这是我的任务列表
//recieves fame from Camera
1. preprocess
//recieves a Frame from preprocess and removes the background
2. remove background
//recieves a Frame from backgroundremover and tracks the vehicles
3. postprocess
如果我一个接一个地运行线程，我认为它仍然会很慢，而不是我认为或同时运行线程，但是它们使用相同对象的问题，声明它们volatile 将意味着线程等待带锁的线程完成它以使用该对象，这将再次意味着系统缓慢，所以我的问题是如何同时运行这些线程而不必等待其他线程？
我在Java 中查看了十几个multithreading 技术，但发现很难想出一种方法来实现这项工作。
到目前为止，我已经看过了
1. Thread synchronization using the keyword volatile
2. Thread synchronization using the keyword synchronized
3. Multiple thread locks using a lock object
4. Using threadpools
5. Using the Countdown Latch
6. Wait and motify
7. Using Semaphores(which seemed like a good idea).
这是我想分解成这些线程的代码
public void VideoProcessor()
{
videProcessorThread = new Thread(new Runnable()
{
@Override
public void run()
{
try{
int i = 0;
while (isPlaying() && isMainScreenONOFF()) {
camera.read(frame);
//set default and max frame speed
camera.set(Videoio.CAP_PROP_FPS, 25);
//get frame speed just incase it did not set
fps = camera.get(Videoio.CAP_PROP_FPS);
//if(frame.height() > imgHeight || frame.width() > imgWidth)
Imgproc.resize(frame, frame, frameSize);
//check if to convert or not
if(getblackAndWhite())
Imgproc.cvtColor(frame, frame, Imgproc.COLOR_RGB2GRAY);
imag = frame.clone();
if(rOI){
//incase user adjusted the lines we try calculate there new sizes
adjustLinesPositionAndSize(xAxisSlider.getValue(), yAxisSlider.getValue());
//then we continue and draw the lines
if(!roadIdentified)
roadTypeIdentifier(getPointA1(), getPointA2());
}
viewClass.updateCarCounter(tracker.getCountAB(), tracker.getCountBA());
if (i == 0) {
// jFrame.setSize(FRAME_WIDTH, FRAME_HEIGHT);
diffFrame = new Mat(outbox.size(), CvType.CV_8UC1);
diffFrame = outbox.clone();
}
if (i == 1) {
diffFrame = new Mat(frame.size(), CvType.CV_8UC1);
removeBackground(frame, diffFrame, mBGSub, thresHold.getValue(), learningRate.getValue());
frame = diffFrame.clone();
array = detectionContours(diffFrame, maximumBlob.getValue(), minimumBlob.getValue());
Vector<VehicleTrack> detections = new Vector<>();
Iterator<Rect> it = array.iterator();
while (it.hasNext()) {
Rect obj = it.next();
int ObjectCenterX = (int) ((obj.tl().x + obj.br().x) / 2);
int ObjectCenterY = (int) ((obj.tl().y + obj.br().y) / 2);
//try counter
//add centroid and bounding rectangle
Point pt = new Point(ObjectCenterX, ObjectCenterY);
VehicleTrack track = new VehicleTrack(frame, pt, obj);
detections.add(track);
}
if (array.size() > 0) {
tracker.update(array, detections, imag);
Iterator<Rect> it3 = array.iterator();
while (it3.hasNext()) {
Rect obj = it3.next();
int ObjectCenterX = (int) ((obj.tl().x + obj.br().x) / 2);
int ObjectCenterY = (int) ((obj.tl().y + obj.br().y) / 2);
Point pt = null;
pt = new Point(ObjectCenterX, ObjectCenterY);
Imgproc.rectangle(imag, obj.br(), obj.tl(), new Scalar(0, 255, 0), 2);
Imgproc.circle(imag, pt, 1, new Scalar(0, 0, 255), 2);
//count and eleminate counted
tracker.removeCounted(tracker.tracks);
}
} else if (array.size() == 0) {
tracker.updateKalman(imag, detections);
}
}
i = 1;
//Convert Image and display to View
displayVideo();
}
//if error occur or video finishes
Image image = new Image("/assets/eyeMain.png");
viewClass.updateMainImageView(image);
}catch(Exception e)
{
e.printStackTrace();
System.out.println("Video Stopped Unexpectedly");
}
//thread is done
}
});videProcessorThread.start();
}
【问题讨论】：
标签： java multithreading opencv