如何使用在OpenCV的类VideoCapture时旋转摄像头？ （样本人脸检测在Android）。 我旋转画布：

How to rotate the camera when using class VideoCapture on OpenCV? (Sample Face Detection on Android). I'm rotating the canvas with:

if (getResources().getConfiguration().orientation == Configuration.ORIENTATION_PORTRAIT)
{
    Matrix matrix = new Matrix();
    matrix.preTranslate(
    (canvas.getWidth() - bmp.getWidth()) / 2,
    (canvas.getHeight() - bmp.getHeight()) / 2);
    matrix.postRotate(270f, (canvas.getWidth()) / 2,
    (canvas.getHeight()) / 2);
    canvas.drawBitmap(bmp, matrix, null);
}

但是从相机图像不旋转：面部优先不工作

but image from Camera doesn't rotate: Face Detect dont work.

照相机从以下接收流：

protected Bitmap processFrame(VideoCapture capture) {

    capture.retrieve(mRgba, Highgui.CV_CAP_ANDROID_COLOR_FRAME_RGBA);

    capture.retrieve(mGray,
    Highgui.CV_CAP_ANDROID_GREY_FRAME);

更新 我做了以下内容：

UPDATE I did the following:

@Override
    protected Bitmap processFrame(VideoCapture capture) {

    if (getResources().getConfiguration().orientation == Configuration.ORIENTATION_PORTRAIT) {
        Core.flip(mRgba.t(), mRgba, 0);
    }

    else {
    }
    capture.retrieve(mRgba, Highgui.CV_CAP_ANDROID_COLOR_FRAME_RGBA);
    capture.retrieve(mDetect_thread.mGray,
            Highgui.CV_CAP_ANDROID_GREY_FRAME);

但就是不工作。当我运行在portret定位程序（在Android设备） - 程序不启动，当我运行的rogram横向 - PROGRAMM的工作，但是当我转动一圈，设备，程序的工作，但图像显示不旋转

But is dont work. When I run the program in portret orientation(on android device)- program don't start When i run the rogram in landscape orientation - programm work, but when i rotation the device, program work, but image on display dont rotation

推荐答案

您的问题主要是一个duplicate这的，除非你正在寻找Android版本。这是很相似，但在这里它是， 90°旋转，可以通过转，然后翻转图像获得的：

Your question is mostly a duplicate of this, except that you are looking for the Android version. It is quite similar but here it is, 90º rotation can be obtained by transposing and then flipping the image:

# rotate 90º counter-clockwise
Core.flip(mRgba.t(), mRgba, 0); //mRgba.t() is the transpose

# rotate 90º clockwise
Core.flip(mRgba.t(), mRgba, 1);

有关其他的旋转，你可以使用 warpAffine ：

For other rotations you can use warpAffine:

Point center = new Point(x,y);
double angle = 90;
double scale = 1.0;

Mat mapMatrix = Imgproc.getRotationMatrix2D(center, angle, scale);
Imgproc.warpAffine(srcMat, dstMat, mapMatrix, Imgproc.INTER_LINEAR);

修改 - 更完整的例子如下：

    /** 
     * Image is first resized-to-fit the dst Mat and then rotated. 
     * mRgba is the source image, mIntermediateMat should have the same type.
     */
    private void rotationTutorial(){
        double ratio =  mRgba.height() / (double) mRgba.width();

        int rotatedHeight = mRgba.height();     
        int rotatedWidth  = (int) Math.round(mRgba.height() * ratio);

        Imgproc.resize(mRgba, mIntermediateMat, new Size(rotatedHeight, rotatedWidth));

        Core.flip(mIntermediateMat.t(), mIntermediateMat, 0);

        Mat ROI = mRgba.submat(0, mIntermediateMat.rows(), 0, mIntermediateMat.cols());

        mIntermediateMat.copyTo(ROI);       
    }


    /** 
     * Image is rotated - cropped-to-fit dst Mat.
     * 
     */
    private void rotationAffineTutorial(){
        // assuming source image's with and height are a pair value:
        int centerX = Math.round(mRgba.width()/2);
        int centerY = Math.round(mRgba.height()/2);

        Point center = new Point(centerY,centerX);
        double angle = 90;
        double scale = 1.0;

        double ratio =  mRgba.height() / (double) mRgba.width();

        int rotatedHeight = (int) Math.round(mRgba.height());       
        int rotatedWidth  = (int) Math.round(mRgba.height() * ratio);

        Mat mapMatrix = Imgproc.getRotationMatrix2D(center, angle, scale);

        Size rotatedSize = new Size(rotatedWidth, rotatedHeight);
        mIntermediateMat = new Mat(rotatedSize, mRgba.type());

        Imgproc.warpAffine(mRgba, mIntermediateMat, mapMatrix, mIntermediateMat.size(), Imgproc.INTER_LINEAR);

        Mat ROI = mRgba.submat(0, mIntermediateMat.rows(), 0, mIntermediateMat.cols());

        mIntermediateMat.copyTo(ROI);
    }

请注意：