Watermark image on camera view is offset

Question

I have created an overlay image to use as a watermark but the image gets offset. I have put the code below, which is based off this post by Ivan Karpan: Watermark image on real time on camera view in iphone

- (void)btCamera_TouchUpInside:(UIButton *)button
{
    // Create the image picker controller
    UIImagePickerController *imagePicker = [[UIImagePickerController alloc] init];
    imagePicker.sourceType =  UIImagePickerControllerSourceTypeCamera;
    imagePicker.cameraViewTransform = CGAffineTransformScale(imagePicker.cameraViewTransform, 1.24299, 1.24299);
    imagePicker.allowsImageEditing = NO;
    imagePicker.delegate = self;

    UIImageView * ivWatermark = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"Watermark.png"]];
    ivWatermark.alpha = WATERMARK_ALPHA;
    ivWatermark.contentMode = UIViewContentModeTopLeft;
    ivWatermark.frame = self.view.frame;
    imagePicker.cameraOverlayView = ivWatermark;
    [ivWatermark release];

    // Show the image picker
    [self presentModalViewController:imagePicker animated:YES]; 
}

- (void) imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info
{
    UIGraphicsBeginImageContext(CGSizeMake(320, 480));
    [(UIImage *)[info objectForKey:UIImagePickerControllerOriginalImage] drawInRect:CGRectMake(0, 0, 320, 480)];
    [[UIImage imageNamed:@"Watermark.png"] drawAtPoint:CGPointMake(0, 0) blendMode:kCGBlendModeNormal alpha:WATERMARK_ALPHA];
    UIImage * image = UIGraphicsGetImageFromCurrentImageContext();
    imageView.image = image;
    UIGraphicsEndImageContext();

    [picker dismissModalViewControllerAnimated:YES];
    UIImageWriteToSavedPhotosAlbum(image, self, @selector(image:didFinishSavingWithError:contextInfo:), nil);

    [picker release];
}

I first create the imagePicker, then I add the watermark to that camera image, but the image is offset. I have also fooled with the scaling as per another post found here: Using the camera on the iPad/iPhone with an overlay

Also, I have read other articles about adding an overlay image to a camera picture but they all seem to share the same issue.

Any help would be great?

Thanks