it's so easy! you can head to https://cohost.org/rc/user/settings/#cohost-plus and then throw some monies at the people who make the website and then you can upload bigger, crisper jpegs and what have you.
something i really appreciate about cohost is that it is something that is not founded under unnerving constant growth philosophies of capitalist investment - no one's breathing down the founders' necks to turn a profit. I feel a lot better about kickin' them some money as a result, because I know they want the website to be better for the sake of making a better website, not to try to make an IPO or please investors. so give them some bux if you can! they're the best <3