带有opencv的Android-图像到灰度

Question

我正在寻找Android中简单的应用示例，该示例使用opencv将彩色图像转换为灰度图像。 我正在尝试使用thic代码，但此行后应用程序崩溃Mat tmp = new Mat(bmp.getWidth(), bmp.getHeight(), CvType.CV_8U); 。

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    ImageView img=(ImageView)findViewById(R.id.imageView1);

    Bitmap bmp = BitmapFactory.decodeResource(getResources(),R.drawable.ic_launcher);

    Mat tmp = new Mat(bmp.getWidth(), bmp.getHeight(), CvType.CV_8U);

    Utils.bitmapToMat(bmp, tmp);

    Imgproc.cvtColor(tmp, tmp, Imgproc.COLOR_RGB2GRAY);
    Imgproc.cvtColor(tmp, tmp, Imgproc.COLOR_RGB2GRAY,4);

    Utils.matToBitmap(tmp, bmp);
    img.setImageBitmap(bmp);
}

Answer 1

真正快捷的方法。 没有opencv。

 private Button button;
 private ImageView image;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    button = (Button)findViewById(R.id.button1);
    image = (ImageView)findViewById(R.id.imageView1);


    button.setOnClickListener(new OnClickListener() {

        @Override
        public void onClick(View v) {

            ColorMatrix matrix = new ColorMatrix();
            matrix.setSaturation(0);

            ColorMatrixColorFilter filter = new ColorMatrixColorFilter(matrix);
            image.setColorFilter(filter);


        }
    });

我只是尝试过，为我工作。

编辑：在此处查看官方文档链接。 http://developer.android.com/reference/android/graphics/ColorMatrix.html#setSaturation(float）

Answer 2

当您处于onCreate() ，尚未布置您的布局，这就是为什么bmp.getWidth()和bmp.getHeight()返回0的原因。
一种方法是重写onWindowFocusChanged()

private ImageView img;
private boolean isFullyInitialized = false;

@Override
protected void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    img=(ImageView)findViewById(R.id.imageView1);
}


@Override
public void onWindowFocusChanged(boolean hasFocus)
{
    super.onWindowFocusChanged(hasFocus);
    if (hasFocus && !isFullyInitialized)
    {
        isFullyInitialized = true;
        openCvCode();
    }
}

private void openCvCode()
{
    Bitmap bmp = BitmapFactory.decodeResource(getResources(),R.drawable.ic_launcher);

    Mat tmp = new Mat(bmp.getWidth(), bmp.getHeight(), CvType.CV_8U);

    Utils.bitmapToMat(bmp, tmp);

    Imgproc.cvtColor(tmp, tmp, Imgproc.COLOR_RGB2GRAY);
    Imgproc.cvtColor(tmp, tmp, Imgproc.COLOR_RGB2GRAY,4);

    Utils.matToBitmap(tmp, bmp);
    img.setImageBitmap(bmp);
}

Answer 3

问题解决了：

public class MainActivity extends Activity {

ImageView img;
Bitmap bitmap;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    img=(ImageView)findViewById(R.id.imageView1);

    bitmap = BitmapFactory.decodeResource(this.getResources(), R.drawable.lena);

    if (!OpenCVLoader.initAsync(OpenCVLoader.OPENCV_VERSION_2_4_2, this, mOpenCVCallBack))
    {
        Log.e("TEST", "Cannot connect to OpenCV Manager");
    }


}

private BaseLoaderCallback  mOpenCVCallBack = new BaseLoaderCallback(this) {
    @Override
    public void onManagerConnected(int status) {
        switch (status) {
                case LoaderCallbackInterface.SUCCESS:
                {

                    Mat tmp = new Mat(bitmap.getWidth(), bitmap.getHeight(),CvType.CV_8UC1);
                     // Convert
                    Utils.bitmapToMat(bitmap, tmp);

                    Mat gray = new Mat(bitmap.getWidth(), bitmap.getHeight(),CvType.CV_8UC1);
                     // Conver the color
                    Imgproc.cvtColor(tmp, gray, Imgproc.COLOR_RGB2GRAY);
                     // Convert back to bitmap
                    Mat destination = new Mat(gray.rows(),gray.cols(),gray.type());

                    Imgproc.adaptiveThreshold(gray, destination, 255, Imgproc.ADAPTIVE_THRESH_MEAN_C, Imgproc.THRESH_BINARY_INV, 15, 4);

                    Utils.matToBitmap(destination, bitmap);
                    img.setImageBitmap(bitmap);

                } break;
                default:
                {
                    super.onManagerConnected(status);
                } break;
            }
    }
    };

}