One way to do this is to use the email function of your smart phone. A member could send an email with an image attached to a specific email address and the server runs a script, when that email is received at the server a new post is created with the image attached. This function would require custom coding.
I marked it as implemented as it appeared as though you were suggesting a way to upload via Mobile which you can do. Your suggestion was too vague at that point to realise it meant anything else.
I have to say, I still don't fully understand what you want to do...
I think you mentioned in the thread at my site that you want to do it without being in the browser.
In that case, for you to be doing something similar with Facebook or Google+ then you must be using the Facebook or Google+ apps. These are native apps. There's nothing you can do on the server and nothing to "figure out".
A native app would need to be developed (at a considerable cost), deployed to an app store/market place and then downloaded to your phone. And in the context of a Gallery add-on or even core forum software, it's way beyond the usual scope of what a forum can afford.
I want to go to my smartphone gallery and be able to upload my images from there... we are starting to arrive on the same page now... using my smartphone I did log onto my site and add new media to my xenmediagallery.. was prompted to select from :