Piper takes two significant photographs during her story, and each one marks a transformation point for her. The first is her passport photo, which she takes after she purposefully "loses" it while abroad with a broad (Nora). Piper says:
[Nora] costumed me in glasses, pearls, and a pair of ugly loafers. […] I was told to get a conservative haircut. (1.62)
This is the scene that closes the first chapter. Piper's like the reverse version of Bond girl, glamming down to avoid detection, and in this moment, Piper entirely loses her identity and becomes Nora's drug mule. Goodbye bucolic Smith days, hello international crime.
Piper has to take another photo when she gets to jail, and the prison ID photo might be the only photo less glamorous than your driver's license pic. Piper says, "Everyone looks either thuggish and murderous or terrified and miserable in their prison ID photo" (3.53). When the shutter snaps on that picture, Piper has officially completed her admittance process, and as such, her transition from free woman to prisoner.
Both photos symbolize shifts in Piper's life away from the path she's "supposed" to be on as an educated and professional white woman. If the first photo—the plain Jane passport pic—represents Piper's descent, though, then arguably her prison ID photo represents the beginning of her rise. After all, it's through going to prison that Piper is actually able to put her past behind her. Once her sentence is served, the crime chapter of Piper's life is closed.