After creating a sim and playing through the tutorial for the bonuses it confers, I'd like to change my sim's gallery image, but I can't figure out how to do so. Searching Google only gives me information on making custom images for the tray, but unfortunately that doesn't help me since my sim is already in play. Is there a way to change the sim's personal picture like how you can change the household picture by clicking the little camera icon beneath the picture?

This is the image in question I want to change, but I can't figure out how to do so, if it is possible at all.

I know you can change the household picture (top one) when saving the household. I don't think there's a way to change the individual pictures within the household.

Aside from the aforementioned custom tray stuff, no.

Try this: Sims 4 Tray Importer at luniversims.com

Though I've never had to use it personally, I believe their program has a means of changing gallery pics.

Please let me know if I'm wrong.