As for your posy/salt, can you try resizing your original high-res picture by cropping off most of the background and then making the longest dimension about 700 pixels. The file size should be about right and should enlarge for us. You have 125 kb per picture, up to four pictures per post and the board makes the thumbnails.
We particularly need a base shot for this one too (even if there's nothing on it) and dimensions.