When you copy any image link to the image section in posting, you need to make sure the image is full size on your screen before copying the link, as the link can incude a image size too.
I use both gallery and Dropbox to post pics. With Drop box in particular, I can free resize the image before copying the link, this allows me to size either smaller or even larger then original size. This can be useful for certain images.
If there is not an obvious link for image, you can right click on image, then select 'properties' from drop down menu, in there you will see link for image, you can then highlight and copy the link.
Hope this helps you a bit.
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