UMat umat = new UMat();
byte mostCommonValue;

fixed (byte* buffer = umat.Bytes)
{
    byte* end = buffer + umat.Bytes.Length;

    int[] counters = new int[256];

    for (byte* pointer = buffer; pointer != end; pointer++)
    {
        counters[*pointer]++;
    }

    mostCommonValue = (byte)Array.IndexOf(counters, counters.Max());
}

Given a UMat we sometimes need to find the most common value in that UMat. This code does it the unsafe (fast) way.

EMGU Finding the most common value in a UMat

C#