如何设置Bitmap的保存质量

[STAThread]
static void Main()
{
    //取得屏幕的截屏,并从剪贴板取得bitmap
    SendKeys.SendWait("^{PRTSC}");
    Bitmap bmp = (Bitmap)Clipboard.GetImage();

    //查找JPEG这种编码
    ImageCodecInfo[] codecs = ImageCodecInfo.GetImageEncoders();
    ImageCodecInfo codec = null;
    foreach (ImageCodecInfo c in codecs)
    {
        if (c.FormatDescription == "JPEG")
            codec = c;
    }

    //设置100种压缩质量并且保存
    EncoderParameters param = new EncoderParameters();
    for (int i = 1; i <= 100; i++)
    {
        param.Param[0] = new EncoderParameter(Encoder.Quality, i);
        bmp.Save(string.Format("C://{0}.jpg", i), codec, param);
    }
}

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