compare ImageView and a drawable picture a pointing to the same picture

Question

how can I test that img1 and R.drawable.picture_1 point to the same picture ?

I tried this but I am printing "NOT OK" instead of ok

    ImageView img1  = (ImageView)findViewById(R.id.imageView1);  
    img1.setImageResource(R.drawable.picture_1);      

    if(R.drawable.picture_1 ==img1.getId())  
    {  
    log.error("OK");  
    }else{  
    log.error("NOT OK");  
    }