For the first time, a major Hollywood film will hit the $20 threshold at the box office, as movie-theater owners test the public's ability to absorb ever higher ticket prices.

Several theaters will charge $20 per adult ticket to IMAX showings of the animated 3-D family film "Shrek Forever After," the fourth "Shrek" installment from DreamWorks Animation. The theaters include the AMC theater in Manhattan's Kips Bay neighborhood, AMC Loews 34, AMC Loews Lincoln Square and AMC Empire 42nd Street.

The...