What is the difference between dot gain and TVI?

TVI is the abbreviation for Tone Value Increase. TVI is a more general measure of the difference in value between the value specified in the source file and the value of the printed piece. Dot gain and TVI are sometimes used interchangeably.

Instead of measuring an increase in dot size, TVI measures changes in tone. It is used when individual ink dots are not used in the printing process. A tone reproduction curve provides a relationship between tonal value increase and dot gain.