Android使用OpenCV CamShift实现目标追踪

CamShift算法基于色值，适用于追踪颜色和背景差异较大的目标。

效果图

以下调试代码，仅供参考：

源码

package com.kongqw;

import android.graphics.Bitmap;

import org.opencv.android.Utils;
import org.opencv.core.Core;
import org.opencv.core.CvType;
import org.opencv.core.Mat;
import org.opencv.core.MatOfFloat;
import org.opencv.core.MatOfInt;
import org.opencv.core.Rect;
import org.opencv.core.RotatedRect;
import org.opencv.core.Scalar;
import org.opencv.core.TermCriteria;
import org.opencv.imgproc.Imgproc;
import org.opencv.video.Video;

import java.util.Collections;
import java.util.List;
import java.util.Vector;

/**
 * Created by kongqingwei on 2017/4/26.
 * ObjectTracker
 */
public  abstract class ObjectTracker {
    private Mat hsv, hue, mask, prob;
    private Rect trackRect;
    private RotatedRect rotatedRect;
    private Mat hist;
    private List<Mat> hsvList, hueList;
    private Bitmap bitmap;
    private MatOfFloat ranges;

    public abstract void onCalcBackProject(Bitmap prob);

    public ObjectTracker(Mat rgba) {
        hist = new Mat();
        trackRect = new Rect();
        rotatedRect = new RotatedRect();
        hsvList = new Vector<>();
        hueList = new Vector<>();

        hsv = new Mat(rgba.size(), CvType.CV_8UC3);
        mask = new Mat(rgba.size(), CvType.CV_8UC1);
        hue = new Mat(rgba.size(), CvType.CV_8UC1);

        prob = new Mat(rgba.size(), CvType.CV_8UC1);
        bitmap = Bitmap.createBitmap(prob.width(), prob.height(), Bitmap.Config.ARGB_8888);

        ranges = new MatOfFloat(0f, 256f);
    }

    public Bitmap createTrackedObject(Mat mRgba, Rect region) {

        //将rgb摄像头帧转化成hsv空间的
        rgba2Hsv(mRgba);

        updateHueImage();

        Mat tempMask = mask.submat(region);

        // MatOfFloat ranges = new MatOfFloat(0f, 256f);
        MatOfInt histSize = new MatOfInt(25);

        List<Mat> images = Collections.singletonList(hueList.get(0).submat(region));
        Imgproc.calcHist(images, new MatOfInt(0), tempMask, hist, histSize, ranges);

        Bitmap bitmap = Bitmap.createBitmap(hue.width(), hue.height(), Bitmap.Config.ARGB_8888);
        Utils.matToBitmap(hue, bitmap);

        // 将hist矩阵进行数组范围归一化，都归一化到0~255
        Core.normalize(hist, hist, 0, 255, Core.NORM_MINMAX);
        trackRect = region;

        return bitmap;
    }

    private void rgba2Hsv(Mat rgba) {

        Imgproc.cvtColor(rgba, hsv, Imgproc.COLOR_RGB2HSV);

        //inRange函数的功能是检查输入数组每个元素大小是否在2个给定数值之间，可以有多通道,mask保存0通道的最小值，也就是h分量
        //这里利用了hsv的3个通道，比较h,0~180,s,smin~256,v,min(vmin,vmax),max(vmin,vmax)。如果3个通道都在对应的范围内，则
        //mask对应的那个点的值全为1(0xff)，否则为0(0x00).
        int vMin = 65, vMax = 256, sMin = 55;
        Core.inRange(
                hsv,
                new Scalar(0, sMin, Math.min(vMin, vMax)),
                new Scalar(180, 256, Math.max(vMin, vMax)),
                mask
        );
    }

    private void updateHueImage() {
        hsvList.clear();
        hsvList.add(hsv);

        // hue初始化为与hsv大小深度一样的矩阵，色调的度量是用角度表示的，红绿蓝之间相差120度，反色相差180度
        hue.create(hsv.size(), hsv.depth());

        hueList.clear();
        hueList.add(hue);
        MatOfInt from_to = new MatOfInt(0, 0);

        // 将hsv第一个通道(也就是色调)的数复制到hue中，0索引数组
        Core.mixChannels(hsvList, hueList, from_to);
    }

    public RotatedRect objectTracking(Mat mRgba) {

        rgba2Hsv(mRgba);

        updateHueImage();
        // 计算直方图的反投影。
        // Imgproc.calcBackProject(hueList, new MatOfInt(0), hist, prob, ranges, 255);
        Imgproc.calcBackProject(hueList, new MatOfInt(0), hist, prob, ranges, 1.0);

        // 计算两个数组的按位连接（dst = src1 & src2）计算两个数组或数组和标量的每个元素的逐位连接。
        Core.bitwise_and(prob, mask, prob, new Mat());

        // 追踪目标
        rotatedRect = Video.CamShift(prob, trackRect, new TermCriteria(TermCriteria.EPS, 10, 1));

        // 将本次最终到的目标作为下次追踪的对象
        trackRect = rotatedRect.boundingRect();

        rotatedRect.angle = -rotatedRect.angle;

        Imgproc.rectangle(prob, trackRect.tl(), trackRect.br(), new Scalar(255, 255, 0, 255), 6);

        Utils.matToBitmap(prob, bitmap);

        onCalcBackProject(bitmap);

         return rotatedRect;
    }
}

使用部分

public Mat onCameraFrame(CvCameraViewFrame inputFrame) {

    mRgba = inputFrame.rgba();
    mGray = inputFrame.gray();

    if (null == objectTracker) {
        objectTracker = new ObjectTracker(mRgba) {
            @Override
            public void onCalcBackProject(final Bitmap prob) {
                MainActivity.this.runOnUiThread(new Runnable() {
                    @Override
                    public void run() {
                        imageView.setImageBitmap(prob);
                    }
                });
            }
        };
    }

    if (null != mTrackWindow) {

        Log.i(TAG, "onCameraFrame: objectTracker = " + objectTracker + "  mTrackWindow = " + mTrackWindow);
        RotatedRect rotatedRect = objectTracker.objectTracking(mRgba);
        Imgproc.ellipse(mRgba, rotatedRect, FACE_RECT_COLOR, 6);

        Rect rect = rotatedRect.boundingRect();
        Imgproc.rectangle(mRgba, rect.tl(), rect.br(), FACE_RECT_COLOR, 3);
    }

    // System.gc();

    return mRgba;
}

int xDown;
int yDown;

@Override
public boolean onTouch(View v, MotionEvent event) {
    int cols = mRgba.cols();
    int rows = mRgba.rows();
    int xOffset = (mOpenCvCameraView.getWidth() - cols) / 2;
    int yOffset = (mOpenCvCameraView.getHeight() - rows) / 2;

    switch (event.getAction()) {
        case MotionEvent.ACTION_DOWN:
            xDown = (int) event.getX() - xOffset;
            yDown = (int) event.getY() - yOffset;
            break;
        case MotionEvent.ACTION_UP:
            int xUp = (int) event.getX() - xOffset;
            int yUp = (int) event.getY() - yOffset;

            // 获取跟踪目标
            mTrackWindow = new Rect(Math.min(xDown, xUp), Math.min(yDown, yUp), Math.abs(xUp - xDown), Math.abs(yUp - yDown));

            // 创建跟踪目标
            Bitmap bitmap = objectTracker.createTrackedObject(mRgba, mTrackWindow);
            imageView.setImageBitmap(bitmap);

            Toast.makeText(getApplicationContext(), "已经选中跟踪目标！", Toast.LENGTH_SHORT).show();
            break;
        default:
            break;
    }
    return true;
}

参考

• 【计算机视觉】人脸实时跟踪1——利用CamShift来跟踪人脸

• 目标跟踪–CamShift