Definitions of solarize:

• verb:   overexpose to sunlight

  Example: "Be careful not to solarize the photographic film"

• verb:   become overepxosed

  Example: "The film solarized"

• verb:   reverse some of the tones of (a negative or print) and introduce pronounced outlines of highlights, by exposing it briefly to light, then washing and redeveloping it
• verb:   expose to the rays of the sun or affect by exposure to the sun