When you sell the cel to someone else, you also 
sell them the right to display it. Generally, 
most people don't care if you keep the image in 
the sold cels section of you site, but nce you 
sell it, once the money is in your hands, you no 
longer have the right to display it with your 
other cels as if it were yours ^^

As for the hanken image, no, you don't have a 
right to tell people to stop using the image. You 
do have a right to tell people not to use your 
scan.

You lose the right to display it as part of your 
collection when you sell it.

-Misha