Rewrite and encode url

Hello,

I try to make an url rewriting wich rewrite all jpg|gif|png to a script.
I write this :
rewrite ^(.*)\.(jp?g|gif|png)$ $scheme://$host/redirection_image/afficher$1 last;

It's work, but if I pass a directory, $1 = /directory/image and I need to use an encoded url like /directory%2Fimage.

How I can make this ?

Thanks :)