Do I have to have "pictures" to file for adultery?

Filing for adultery and proving adultery in court are two different things.  Filing for adultery gets your foot in the door, so to speak.  It allows you to open up a divorce case.  To file for adultery, your complaint for divorce must allege at least one specific instance of adultery (e.g., location, time and the identity of the paramour).  

To prove adultery in court, you need to take that a step further and provide evidence that your spouse had the opportunity and inclination to commit the alleged adultery.  It can sometimes be useful to scan social media or even hire a private investigator to gather such evidence.

That said, it is rare for a court to grant a divorce on adultery grounds.  Generally, Judges prefer to grant no-fault divorces over fault-based divorces, if given the option.  Not coincidentally, Courts almost always set divorce trial dates at least 12 months after the parties' separation, thereby ensuring the Judge has the option of granting a no-fault divorce.