Properties for this one is 600 x 392 with 240 dpi for resolution.
I downloaded my own image which I size at 1100 on the longest (or tallest) side with a resolution of 240 dpi. I downloaded my own and checked its file size. The forum downsized it to 1024 x 819 with a resolution of 240 dpi.
Something is going wrong with how your images are being uploaded, Skwaz.