Android with opencv - 图像到灰度

Question

我正在寻找Android中应用程序的简单示例，该应用程序使用opencv将彩色图像转换为灰度。我正在尝试使用代码，但是在此行Mat tmp = new Mat(bmp.getWidth(), bmp.getHeight(), CvType.CV_8U); 后应用程序崩溃。

@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

真正快速的方法。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

刚刚尝试过，对我有用。

编辑：查看此处的链接以获取官方文档。http://developer.android.com/reference/android/graphics/ColorMatrix.html#setSaturation（浮子）

Answer 2

您的布局尚未布局，而您处于onCreate()，这就是为什么bmp.getWidth()和bmp.getHeight()返回 0 的原因。
一种方法是覆盖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

问题已解决：

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;
            }
    }
    };

}