在Android上使用带有OpenCV的Camera LED Flash

Question

I have an application using OpenCV for Android and was wondering if it was possible to enable the camera's LED.

Currently my camera is set up using the following code:

camera = new VideoCapture(Highgui.CV_CAP_ANDROID);

All examples I've seen which enable the LED Flash require Camera.Parameters which I don't have access to with this camera setup.

Is there any simple way to enable the LED without switching to using the basic Camera class for my videostream, as this tends to be much slower.

Thanks for any help in advance.

Answer 1

In OpenCV for Android 2.4, you can do this,

mCamera.set(
  Highgui.CV_CAP_PROP_ANDROID_FLASH_MODE,
  Highgui.CV_CAP_ANDROID_FLASH_MODE_ON
);

Other options are: CV_CAP_ANDROID_FLASH_MODE_AUTO , CV_CAP_ANDROID_FLASH_MODE_OFF , CV_CAP_ANDROID_FLASH_MODE_TORCH and CV_CAP_ANDROID_FLASH_MODE_REDEYE .

However, using this causes the application to automatically close on my tablet (Asus TF101). Hopefully it works on others.

Answer 2

You can use extends JavaCameraView

public class Tutorial2View extends JavaCameraView{

private static final String TAG = "Sample::Tutorial2View";

private Context myreference;
private static boolean isFlashLightON = false;
public Tutorial2View(Context context, AttributeSet attrs) {
    super(context, attrs);
    this.myreference = context;
}

public List<String> getEffectList() {
    return mCamera.getParameters().getSupportedColorEffects();
}

public boolean isEffectSupported() {
    return (mCamera.getParameters().getColorEffect() != null);
}

public String getEffect() {
    return mCamera.getParameters().getColorEffect();
}

public void setEffect(String effect) {
    Camera.Parameters params = mCamera.getParameters();
    params.setColorEffect(effect);
    mCamera.setParameters(params);
}

public List<Size> getResolutionList() {
    return mCamera.getParameters().getSupportedPreviewSizes();
}

public void setResolution(Size resolution) {
    disconnectCamera();
    mMaxHeight = resolution.height;
    mMaxWidth = resolution.width;
    connectCamera(getWidth(), getHeight());
}

public Size getResolution() {
    return mCamera.getParameters().getPreviewSize();
}

// Setup the camera
public void setupCameraFlashLight() {
    Camera  camera = mCamera;
    if (camera != null) {
        Parameters params = camera.getParameters();

        if (params != null) {
            if (isFlashLightON) {
                isFlashLightON = false;
                params.setFlashMode(Parameters.FLASH_MODE_OFF);
                camera.setParameters(params);
                camera.startPreview();
            } else {
                isFlashLightON = true;
                params.setFlashMode(Parameters.FLASH_MODE_TORCH);
                camera.setParameters(params);
                camera.startPreview();

            }
        }
    }

}

}

Call setupCameraFlashLight(); to ON OFF the LED light

Answer 3

If you use JavaCameraView you can simply add on the end two methods to your JavaCameraView.java class:

public void turnOffTheFlash() {
    Camera.Parameters params = mCamera.getParameters();
    params.setFlashMode(params.FLASH_MODE_OFF);
    mCamera.setParameters(params);
}

public void turnOnTheFlash() {
    Camera.Parameters params = mCamera.getParameters();
    params.setFlashMode(params.FLASH_MODE_TORCH);
    mCamera.setParameters(params);
}

You can run them in your activity as follow:

private JavaCameraView javaCameraView;

javaCameraView.turnOnTheFlash();

javaCameraView.turnOffTheFlash();

Mayby you should use FLASH_MODE_ON rather than FLASH_MODE_TORCH.

It works for my on OpenCV 2.4.9.

Answer 4

It seems there is no easy way to do this. The only option is to use the default Android Camera class and take the slight performance hit.