java - 相机预览叠加到Android应用程序中的灰度效果

Question

我想将相机预览更改为灰度效果。如何做到这一点？我正在尝试，但无法从以下代码中获得任何输出：

protected void onActivityResult(int requestCode, int resultCode, Intent imageReturnedIntent) {
        super.onActivityResult(requestCode, resultCode, imageReturnedIntent);

        if (resultCode == RESULT_OK) {
            Uri selectedImage = imageReturnedIntent.getData();
            basefile = preview.file;
            getRealPathFromURI(selectedImage);
            try {
                loadBaseImage(getBitmapFromURI(selectedImage));
            } catch (FileNotFoundException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }
        }
        try {
            preview.startCamera();
        } catch (Exception e) {
            toast("Ops!" + e.getMessage());
            e.printStackTrace();
        }
    }

    private void loadBaseImage(Bitmap bmp ) {
        try {
            photoBase.setBitmap(bmp);
            photoBase.selectedPicture();
        } catch (Exception e) {
            toast("Ops!" + e.getMessage());
            e.printStackTrace();
        }
    }

    public Bitmap getBitmapFromString(String src)
            throws FileNotFoundException {
        Uri uri = Uri.fromFile(new File(src));
        return getBitmapFromURI(uri);
    }
        public Bitmap getBitmapFromURI(Uri uri )
        throws FileNotFoundException {
        InputStream imageStream = getContentResolver().openInputStream(uri);
        Bitmap bmp = BitmapFactory.decodeStream(imageStream);
        return bmp;
    }

    public Toast getToast(String dados, int duration) {
        return Toast.makeText(this, dados, duration);
    }

    public void toast(String dados) {
        final Toast t = getToast(dados, Toast.LENGTH_LONG);
        t.setGravity(Gravity.CENTER, 0, 0);
        t.show();
    }
    private void setFullBrightness() {  
        WindowManager.LayoutParams layout = getWindow().getAttributes();
        layout.screenBrightness = 1F;
        getWindow().setAttributes(layout);
    }


    private String getSdcardCameraOverlay() {
        return PreferenceManager.getDefaultSharedPreferences(getApplicationContext()).getString("camera_overlay_directory", "/sdcard/CameraOverlay/");
    }
}