private int rotateColor(int color, float rad)
{
float deg = rad * 180 / (float)Math.PI;
int r = Color.GetRedComponent(color);
int g = Color.GetGreenComponent(color);
int b = Color.GetBlueComponent(color);
ColorMatrix cm = new ColorMatrix();
ColorMatrix tmp = new ColorMatrix();
cm.SetRGB2YUV();
tmp.SetRotate(0, deg);
cm.PostConcat(tmp);
tmp.SetYUV2RGB();
cm.PostConcat(tmp);
float[] a = cm.GetArray();
int ir = floatToByte(a[0] * r + a[1] * g + a[2] * b);
int ig = floatToByte(a[5] * r + a[6] * g + a[7] * b);
int ib = floatToByte(a[10] * r + a[11] * g + a[12] * b);
return(Color.Argb(Color.GetAlphaComponent(color), pinToByte(ir), pinToByte(ig), pinToByte(ib)));
}