c# 图片格式转换

ImageConvert(@"E:\素材\xx.png", @"E:\素材\xx.ico");

public static void ImageConvert(string imagePath,string outPath)
 {
     Image img = Image.FromFile(imagePath);
     var width = 32;
     var height = 32;
     Size size;
     if ((width == 1) && (height == 1))
     {
         size = new Size(img.Width, img.Height);
     }
     else
     {
         size = new Size((int)width, (int)height);
     }
     Bitmap bitmap = new Bitmap(img, size);

     ImageFormat format = ImageFormat.Icon;

     using (FileStream fs = new FileStream(outPath, FileMode.Create))
     {
         if (format == ImageFormat.Icon)
         {
             IntPtr hwd = bitmap.GetHicon();
             Icon icon = Icon.FromHandle(hwd);
             icon.Save(fs);
         }
         else
         {
             bitmap.Save(fs, format);
         }
     }
 }