Patent ID: 7405748

Claim:
An apparatus for monitoring a video signal, comprising: means for inputting a Y/color difference component signal (Y, Pr, Pb); means for setting upper limit values S and lower limit values T corresponding to all components of an RGB component signal (R, G, B); means for determination as to the existence of a gamut error, said determination means making determination as to whether at least one of a first condition Y>S+α×Pb+β×Pr (where each of α and β is a predetermined coefficient) indicating that at least one of R, G and B components is larger than the upper limit value S and a second condition Y<T+γ×Pb+δ×Pr (where each of γ and δ is a predetermined coefficient) indicating that at least one of the R, G and B components is smaller than the lower limit value T is satisfied; and means for making a gamut error state visually recognizable when the first condition or the second condition is satisfied.