Your question, unfortunately, answers itself--legally, if your probation has a no drink clause, then if you are photographed drinking, you will have violated your probation. Factually, if there photos have been faked or modified, or if it is unclear who is in the photo or what they are drinking, it may be possible to avoid the violation, if your PO can be convinced that it was not you drinking; however, if the PO accepts the photographs as evidence of your drinking, then you would be in violation of your probation. You may wish to consider whether you would be better served by admitting to the violation and asking for a second chance (and help, as appropriate), rather than by waiting until the photos are sent to your PO. Good luck.