There is a very simple way of copying images to a forum post depending on what browser you use (Chrome, Firefox, Opera, Safari or that horrible thing that comes with Windows). With Chrome you can simply right click the image and 'Copy image URL' or 'Open Image In New Tab', you then put the image's URL in [IMG] [ /IMG] tags in your post. Personally I open each image I will add to the post in their own tabs, I then copy and paste X amount of image tags into my post, then copy image URLs in from there.
That works for almost all websites but some require you to go into 'Inspect Element'. Firefox is similar, I've never used Opera and I don't use Macs. But it is easy enough to find the information you need for the browser you use.
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