Question

我正在Android中寻找简单的app应用示例，它使用opencv将彩色图像转换为灰度。我正在尝试使用这些代码，但应用程序在此行Mat tmp = new Mat(bmp.getWidth(), bmp.getHeight(), CvType.CV_8U);之后崩溃。

@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。

SELECT substring(Code,1,6) as Code,
       SUM(Number) AS [Sum] -- Add this line

From Table

Group by substring(Code,1,6)

Order By Code

我刚试过，对我有用。

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

Answer 2

当您在onCreate()时，您的布局尚未布局，这就是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;
            }
    }
    };

}

Android与opencv - 图像到灰度

3 个答案: