ILSWriter wrote :you modified the original, keeping the same reference number
How does this board get an image? I know how to point to it in my post. But if I point to an image on my website and then change that image on my site, will the image in my post here change? If so, that implies that every time somebody reads my post here somehow this board queries my web site and down loads the image again. Is that how it works? I don't really care I'm just curious.
Both of the images directly above link back to "/doctor/images/doctor_121a.jpg" on your site, they have not been copied across to the Forum host server. If you right click any of the images here you and "Inspect Element", "View Image Info", or similar, then you get to see where the image actually resides.
So yes, if you make a change to an image and preserve its name then the server presents your update always referring back to you.