How can I view images at different sizes?

For example, if I want to see a gif in medium size to make it smaller. How can I do this?

@sammyliimex  
for gifs that have been uploaded to the site it’s a little tricky but it can be done like this. go to “vs” on the image and you’ll get a link like this:
 
https://derpicdn.net/img/view/2016/5/11/1151834.gif
 
then you have to rewrite it a little. erase “view” and the file extension:
 
https://derpicdn.net/img/2016/5/11/1151834
 
and then you can add  
/large.gif  
/medium.gif  
/small.gif  
/thumb.gif  
/thumb_small.gif  
/thumb_tiny.gif
 
to the end to get various sizes:  
 
 
 
 
 

 
it’s a little clunky, yes, but it’s at this point the only way to do it.

Thank you