Color Transient Improvement (CTI) is a technique for improving color television images in analog picture display. The CTI technique is used to improve abrupt color transitions and edge representation in television images from classic television standards.
The fact that colored edges in television pictures have a certain blurring is due to the difference in bandwidth with which the luminance signal (Y) and the chrominance signals (U, V or Cb and Cr) are represented. The bandwidth difference is about 5:1. The same applies to the rise time of luminance and chrominance transitions, where the rise time from the luminance signal is only about one fifth of that of the chrominance signals, resulting in the signals being displayed in a slurred manner.
These slurs are compensated for by electronic circuits that improve the slope of abrupt color transitions and at the same time compensate for the resulting time differences between luminance and chrominance signals so that the edges of the two signals correlate with each other.