Defining color using C #

I am developing a winForm C # program for detecting smiles using a webcam using the EmguCV library. For this, I use the haarcascade_smile XML file. However, in some cases, a detection error occurs: sometimes the line of the shape of the oral cavity is erroneously identified as a mouth.

I have a new idea, which is to look for red in addition to the original xml file to improve mouth detection and try to reduce the error rate.

Does anyone know of a command or library that can be used to detect red?

Many thanks:)

var smiles = grayframe.DetectHaarCascade(_smiles, 
                                         ScaleIncreaseRate, 
                                         MinNeighbors, 
                                         HAAR_DETECTION_TYPE.DO_CANNY_PRUNING, 
                                         new Size(WindowsSize, WindowsSize))[0];
if (smiles.Length == 0)
{
    // Number of smile face detected is 0
}
else
{

}