Hi ikas,
I do not know if what you want to do is possible. But why do you wish to upload a photo which only you can see? Easier to keep it private by not uploading it.
If you wish to share it with certain people then you could upload a dummy image which says something to the effect of “ask me if you want me to see this photo”
Maybe you could achieve what you want by having two trees online. One has no photos and is public and one with photos which is private but you can let others have access to it.
I have for some time had a wish that I could, on my Ancestry tree, share the notes which are included for most of the people - but only to selected people. That would let them see far more than the bare facts of bmd dates and places. However it seems that giving them a guest access will not do. For them to see my notes I have to give them full ownership rights which would let them edit anything on my tree or even delete it. Not a disaster if they did delete or corrupt it as it is just a copy of part of the main tree on my home computers. But I would be happier if they had Read Only access.