Why CameraX image distorted when saved in Android phone Redmi 9T?

I am using the new device Redmi 9T. Following the basic setup from this post, i manage to up and run an app using CameraX. Everything works fine until i want to save the frame to the local, in the setAnalyzer function

private void bindImageAnalysis(@NonNull ProcessCameraProvider cameraProvider) {
    ImageAnalysis imageAnalysis =
            new ImageAnalysis.Builder().setTargetResolution(new Size(720, 1280))
                    .setBackpressureStrategy(ImageAnalysis.STRATEGY_KEEP_ONLY_LATEST).build();

    imageAnalysis.setAnalyzer(ContextCompat.getMainExecutor(this), new ImageAnalysis.Analyzer() {
        @Override
        public void analyze(@NonNull ImageProxy imageProxy) {
            @SuppressLint("UnsafeExperimentalUsageError") Image image = imageProxy.getImage();
            Bitmap finalBitmap = getFinalScaledRotatedBitmap(image,270); //rotate it properly (portrait)
            saveBitmap(finalBitmap, "test"); //save with a dummy name
            imageProxy.close();
        }
    });
    OrientationEventListener orientationEventListener = new OrientationEventListener(this) {
        @Override
        public void onOrientationChanged(int orientation) {
            textView.setText(Integer.toString(orientation));
        }
    };
    orientationEventListener.enable();
    Preview preview = new Preview.Builder().build();
    CameraSelector cameraSelector = new CameraSelector.Builder()
            .requireLensFacing(CameraSelector.LENS_FACING_FRONT).build();
    preview.setSurfaceProvider(previewView.createSurfaceProvider());
    cameraProvider.bindToLifecycle((LifecycleOwner)this, cameraSelector,
            imageAnalysis, preview);
}

 /*
 *  Rotate the image with a rotation degree
 */
 private Bitmap getFinalScaledRotatedBitmap(Image imageData, int viewRotation){
    Bitmap originalBitmap = toBitmap(imageData);
    Matrix matrix = new Matrix();
    matrix.postRotate(viewRotation);
    matrix.postScale(-1.0f, 1.0f);
    Bitmap scaledBitmap = Bitmap.createScaledBitmap(originalBitmap, originalBitmap.getWidth(), originalBitmap.getHeight(), true);
    Bitmap finalRotatedBitmap = Bitmap.createBitmap(scaledBitmap, 0, 0, scaledBitmap.getWidth(), scaledBitmap.getHeight(), matrix, true);
    return finalRotatedBitmap;
}

/*
*  Convert Image format to Bitmap
*/
private Bitmap toBitmap(Image image) {
    Image.Plane[] planes = image.getPlanes();
    ByteBuffer yBuffer = planes[0].getBuffer();
    ByteBuffer uBuffer = planes[1].getBuffer();
    ByteBuffer vBuffer = planes[2].getBuffer();

    int ySize = yBuffer.remaining();
    int uSize = uBuffer.remaining();
    int vSize = vBuffer.remaining();

    byte[] nv21 = new byte[ySize + uSize + vSize];
    //U and V are swapped
    yBuffer.get(nv21, 0, ySize);
    vBuffer.get(nv21, ySize, vSize);
    uBuffer.get(nv21, ySize + vSize, uSize);

    YuvImage yuvImage = new YuvImage(nv21, ImageFormat.NV21, image.getWidth(), image.getHeight(), null);
    ByteArrayOutputStream out = new ByteArrayOutputStream();
    yuvImage.compressToJpeg(new Rect(0, 0, yuvImage.getWidth(), yuvImage.getHeight()), 100, out);

    byte[] imageBytes = out.toByteArray();
    return BitmapFactory.decodeByteArray(imageBytes, 0, imageBytes.length);
}

/*
*  Save Bitmap to local
*/
public void saveBitmap(Bitmap bitmap, String personName) {
    String ROOT =
            Environment.getExternalStorageDirectory().getAbsolutePath() + File.separator + "cameraX";

    File myDir = new File(ROOT + File.separator + personName);
    if (!myDir.mkdirs()) {
        Log.e("FileUtil", "save dir fails");
    }

    String fileName = (new SimpleDateFormat("yyyyMMdd_HHmmss_SSS")).format(Calendar.getInstance().getTime()) + ".jpeg";
    File file = new File(myDir, fileName);
    if (file.exists()) {
        file.delete();
    }

    try {
        FileOutputStream out = new FileOutputStream(file);
        bitmap.compress(Bitmap.CompressFormat.JPEG, 100, out);

        out.flush();
        out.close();
    } catch (Exception var6) {
        Log.e("fileUtil", var6.getMessage());
    }

}

Output? (regardless of Lens front or back)

The thing is, it works fine in other device like honor 8x, or realme. So, what could possibly go wrong?

The issue might be with your conversion method toBitmpa(), it assumes the image's format is NV21, but unfortunately not every YUV_888_420 buffer is NV21 format. it can also be NV12, YU12 or YV12 format.

The official CameraX documentation already provides a way to convert YUV images to RGB bitmaps which you should use, it's at the bottom of this section from the documentation.

For sample code that shows how to convert a Media.Image object from YUV_420_888 format to an RGB Bitmap object, see YuvToRgbConverter.kt.