Hand center detection

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I am detecting the hand, using Defects but i need only the palm without fingers, the center of the palm without fingers. I wrote this piece of code:

int ht, //height left 
    hb, //height right
    wl, //width top
    wr; //width botton
bool ok = true;
label1.Text = label1.Text + ",";
for(int i = 10; i < skin.Height - 10; i += 10)
    for(int j = 10; j < skin.Width - 10; j+=10)
    {
        wl = wr = j;
        ht = hb = i;
        if(skin[i, j].MCvScalar.v0 == 0)
            ok = true;
            while(ok)
            {
                wl--;
                wr++;
                ht--;
                hb++;
                if( (wl <= 0 || wr >=skin.Height || ht <= 0 || hb >=skin.Width) || 
                    ( skin[j, ht].MCvScalar.v0 != 0 || skin[j, hb].MCvScalar.v0 != 0 ||
                      skin[wl, j].MCvScalar.v0 != 0 || skin[wr, j].MCvScalar.v0 != 0) )
                {
                    if(maxCircleRadius < (wr - wl) / 2)
                    {
                        maxCircleRadius = (wr - wl) / 2;
                        palmCenter.X = (wr + wl) / 2;
                        palmCenter.Y = (ht + hb) / 2;
                        currentFrame.Draw(new CircleF(new PointF(palmCenter.X, palmCenter.Y), 3), new Bgr(200, 125, 75), 2);
                        label1.Text = maxCircleRadius.ToString();
                    }
                    ok = false;
                }
            }
    }

but it takes around 0.5 sec for each image to detect the palm wich is way too much for me. Is there any other solution to detect the palm without fingers?