gistfile1.m

-(void)scrollViewDidScroll:(UIScrollView *)scrollView
{
    UIImageView *img=(UIImageView *)[self.view viewWithTag:2];

    CGFloat y=-scrollView.contentOffset.y;
    if (y>0)
    {
        [img setFrame:CGRectMake(0, 0, CGRectGetWidth(self.view.frame)+y*CGRectGetWidth(self.view.frame)/330,y+330 )];
        [img setCenter:CGPointMake(self.view.center.x, img.center.y)];
    }
}