Camera real time image processing - Android Q&A, Help & Troubleshooting

I need to do some image processing in real time on mobile. I am using camera2 library. I managed to put camera preview directly on surfaceView but when i redirect it to ImageReader to do something with frames before i preview them it goes really slow, and there is not even processing just taking Y value from YUV_420_888 and converting it to gray picture in ARGB_8888 format. Code is below. For that one for loop i need about 600ms. And for image processing i will need to go trough that image at least one more time. In Bits array i form ARGB_8888 format out of Y array which is Y value of YUV_420_888 format. I test it on phone with Quad Core 1ghz processor and 1gb ram. Is there any way to speed this code up so i can go lets say 2-3 times trough picture and have at least 7-10 fps? If i delete for loop and just measure fps its 8-12fps. Why is it so slow compering to 25fps when i put it directly on surfaceView?
Code:
private final CameraDevice.StateCallback mStateCallback = new CameraDevice.StateCallback() {
@Override
public void onOpened(@NonNull CameraDevice cameraDevice) {
// This method is called when the camera is opened. We start camera preview here.
mCameraOpenCloseLock.release();
mCameraDevice = cameraDevice;
createCameraPreviewSession();
mImageReader.setOnImageAvailableListener(new ImageReader.OnImageAvailableListener() {
@Override
public void onImageAvailable(ImageReader reader) {
Image image = reader.acquireLatestImage();
if(image != null) {
ByteBuffer buffer0 = image.getPlanes()[0].getBuffer();
byte[] Y = new byte[buffer0.remaining()];
buffer0.get(Y);
byte[] Bits = new byte[Y.length*4]; //That's where the RGBA array goes.
int Ylength = Y.length;
for (int i = 0; i < Ylength; i++) {
int i1 = i*4;
Bits[i1] =Y[i];
Bits[i1 + 1] =Y[i];
Bits[i1 + 2] = Y[i];
Bits[i1 + 3] = -1;//0xff, that's the alpha.
}
Bitmap bm = Bitmap.createBitmap(image.getWidth(), image.getHeight(), Bitmap.Config.ARGB_8888);
bm.copyPixelsFromBuffer(ByteBuffer.wrap(Bits));
Bitmap scaled = Bitmap.createScaledBitmap(bm, surfaceView.getWidth(), surfaceView.getHeight(), true);
Canvas c;
c = surfaceHolder.lockCanvas();
c.drawBitmap(scaled, 0, 0, null);
surfaceHolder.unlockCanvasAndPost(c);
image.close();
time2 = System.nanoTime();
Log.d("Vreme",Double.toString(1000000000/(time2-time1))+"fps");
time1 = System.nanoTime();
}
}
},mBackgroundHandler);
}
@Override
public void onDisconnected(@NonNull CameraDevice cameraDevice) {
mCameraOpenCloseLock.release();
cameraDevice.close();
mCameraDevice = null;
}
@Override
public void onError(@NonNull CameraDevice cameraDevice, int error) {
mCameraOpenCloseLock.release();
cameraDevice.close();
mCameraDevice = null;
}
};