private static Rectangle GetCropZone(Image<Bgra, Byte> myImg)
{
int top = 0;
int left = 0;
int bottom = myImg.Rows - 1;
int right = myImg.Cols - 1;
top = FindTopTransparent(myImg);
left = FindLeftTransparent(myImg);
bottom = FindBottomTransparent(myImg);
right = FindRightTransparent(myImg);
return new Rectangle(left, top, (right - left), (bottom - top));
}