They occur because movies are filmed at different frame sizes, or aspect ratios. "Lady Bird", shot in widescreen should appear differently than "Star Wars", which was shot in Cinemascope.

All 23 of Tom and Jerry's shorts produced using the CinemaScope process are collected together for the first time on Blu-ray. Also includes two stand-alone Spike & Tyke cartoons, Give & Tyke and ...

What made VistaVision special compared to rival formats like CinemaScope was its larger negative ... both minimalist and maximalist in the same movie. "We use it not only for capturing aspects ...