Images sending at the wrong size

I’m trying to send a background to someone and the image is a 3-zone background, 1920x1136. When I upload it to the forums, it sends at a smaller size, 960x568. I haven’t had this problem before, how can I get around it?

That’s strange but maybe use this? o.o

http://www.simpleimageresizer.com/

I tried that, but my original image is the right size already and using the website-resized image is still scaled down to 960x568. Thank you though!