1) Did you take the image with your own property?
`If yes, proceed to 2.
`If no, proceed to 5
2) Did you consensually share the image with anyone else?
`If yes, proceed to 3
`If no, proceed to 4
3) The image is owned by you and whoever you consensually shared it with. Mature adults would generally assume that further consent has to be received before it can be shared more.
4) You, and you alone, own the image, unless you, of your own free will, decide to share ownership of the image.
5) Did you give any form of consent for the photograph to be taken?
`If yes, proceed to 6
`If no, proceed to 7
6) The image is owned by the photographer and whoever he or she decides to share that image with. Generally, mature adults would do this sharing with some form of consent from the person who was photographed: e.g. "Hey stranger, can I share this photograph of you on Facebook?"
7) Your image is owned by the photographer and whoever he or she decides to consensually share that image with. This can be done without the consent of the person(s) who is/are the subject of the image and (in multiple occurrences) people/companies have been brought to court for publishing images of subjects who did not request being photographed.
`Note 1: all of the above assumes you are a living person. If you are neither alive nor a person then you can't own images, except maybe in the case of a non-human who took a selfie.
`Note 2: all of the above assumes that you treat your ownership of your images, and the hypothetical/real ownership of other peoples' images, in the same way. If you are instead okay with violating peoples' consent then I don't know what else needs to be stated.
EDITED TO ADD: Turns out that patriarchy actually undermines our fitness as a species.