Temporal Information (TI) is a standardized measure, defined in ITU-T P.910 section 7.8, of how much the picture changes from frame to frame. It is the spread (standard deviation) of the pixel-by-pixel difference between consecutive frames, so fast motion and scene cuts push TI up while a static shot keeps it low. It is the companion to Spatial Information (SI): plotting every source with TI on one axis and SI on the other shows content coverage at a glance. TI matters because motion drives how hard content is to compress - fast pans are murder for any encoder, and high-TI clips stress both encoders and the metrics meant to track them. A defensible source set spreads across the SI/TI plane, deliberately including the high-motion corner where systems struggle, not clustering in the convenient low-motion corner that reports a quality production will never see. With SI, TI converts the vague requirement that sources be varied into a measurable map, so the test exposes the system's weak spots instead of hiding them.
