Try This
public bool CheckImgSize(string ImgPath,string SelectWidth,string SelectedHeight)
{
Bitmap bp = new Bitmap(ImgPath);
Double Width=double.Parse(SelectWidth)*72;
Double Height=double.Parse(SelectedHeight)*72;
if ((bp.Width != Width) && (bp.Height != Height))
{
return false;
}
else
return true;
}