Best thing to do in a vBulletin/phpBB forum: use the BB code. It has a bit of the look and feel of HTML, but today most photo-hosting services (flickr, picasa, photobucket and a tousand others) allow you to grab the BB code for different sizes of each photo and simply copy it into any forum message you are working on.
The code looks like this
Code:
[url=https://flic.kr/p/6bQWMp][img]https://c2.staticflickr.com/4/3589/3404498465_d14e1bfdef_o.jpg[/img][/url][url=https://flic.kr/p/6bQWMp]hobie_cat[/url] by [url=https://www.flickr.com/photos/stefanschmitz/]Stefan Schmitz[/url], auf Flickr
and does that
hobie_cat by Stefan Schmitz, auf Flickr
now you MIGHT not want to publish the entire URL, the what- and whereabouts, so you CAN shorten the code and cut the description off. Therefor you just suppress the commenting part in the BB Code until only the important part is left (open and close of the first two brackets)
Code:
[url=https://flic.kr/p/6bQWMp][img]https://c2.staticflickr.com/4/3589/3404498465_d14e1bfdef_o.jpg[/img][/url]
finally the picture now looks like this
Way better without the footnote, isn't it?
If you ask yourself, what that "auf" may be and stuff ... I'm German, working on a Linux-System in German language here in France, where I live for the last 20 years...