It's not totally on your end... because of what you just described tells me that they have the PHP settings set to size lower than can handle a picture over 8 MB. And it also means (and probably for security and performance reasons) that they would not be willing to increase it. So, yes, on your end - you'll need to reduce the size of the files before uploading. But, I will say that some hosts will increase it for you and many even allow uploads up to 25 MB by default.