When a movie is selected to premiere at a festival, it’s a time of celebration for the filmmakers. But it’s not an end to their labors.

Very often, there’s work left to be done on the movie before it’s unveiled to the world. While fans excitedly scroll through the latest showcase at an upcoming festival, some of the filmmakers might still be sweating over making their movies look and sound exactly as intended.

It’s all a normal part of the process when postproduction and festival calendars overlap, whether at the Venice Film Festival, which opens on Wednesday and runs through Sept. 7, or at Cannes or Sundance.

After Venice announced its latest lineup, many filmmakers were still polishing the sound mixing, color correction and visual effects of their movies. In late July, Dea Kulumbegashvili, the Georgian director of the competition title “April,” was still completing aspects of her film about an obstetrician who performs illegal abortions.

Reached at Studio Babelsberg in Potsdam, Germany, she said she was waiting on around 10 shots with visual effects that needed to be finalized. She described the nature of the effects somewhat enigmatically as “a character” in the film that required a careful eye across many long-sequence shots.