Patent ID: 7365798

Claim:
A video signal identification device that determines whether a signal format of an input video signal is an RGB signal or a Y/color difference signal, the video signal identification device comprising: a clamp circuit that clamps the input video signal to adjust a pedestal level of the input video signal to a predetermined signal level and outputs the clamped video signal; an AD conversion circuit that receives the video signal output from the clamp circuit; a video signal-relating information acquisition module that acquires a preset piece of video signal-relating information, in response to an output video signal from the AD conversion circuit; and a video signal identification module that obtains an RGB probability, which represents a possibility that the signal format of the input video signal is the RGB signal, and a color difference probability, which represents a possibility that the signal format of the input video signal is the Y/color difference signal, based on the preset piece of video signal-relating information acquired by the video signal-relating information acquisition module, and compares the RGB probability with the color difference probability to determine whether the signal format of the input video signal is the RGB signal or the Y/color difference signal, wherein the video signal identification module sets the predetermined signal level in the clamp circuit to a substantially minimum level in a dynamic range of the AD conversion circuit on the assumption that the signal format of the input video signal is the RGB signal, causes the video signal-relating information acquisition module to acquire a maximum RB value, which is a largest value of an R signal component and a B signal component output from the AD conversion circuit, as the preset piece of video signal-relating information, and obtains the RGB probability corresponding to a degree of largeness of the acquired maximum RB value, the video signal identification module setting the predetermined signal level of a color difference signal component in the clamp circuit to a substantially center level in the dynamic range of the AD conversion circuit on the assumption that the signal format of the input video signal is the Y/color difference signal, causing the video signal-relating information acquisition module to acquire a minimum color difference value, which is a smallest value of the color difference signal component output from the AD conversion circuit, as the preset piece of video signal-relating information, and obtaining the color difference probability corresponding to a degree of smallness of the acquired minimum color difference value.