C#无损高质量压缩图片代码

本文实例为大家分享了C#无损高质量压缩图片的具体代码，供大家参考，具体内容如下

/// 无损压缩图片
/// <param name="sFile">原图片</param>
/// <param name="dFile">压缩后保存位置</param>
/// <param name="dHeight">高度</param>
/// <param name="dWidth"></param>
/// <param name="flag">压缩质量(数字越小压缩率越高) 1-100</param>
/// <returns></returns>

public static bool GetPicThumbnail(string sFile, string dFile, int dHeight, int dWidth, int flag)
{
  System.Drawing.Image iSource = System.Drawing.Image.FromFile(sFile);
  ImageFormat tFormat = iSource.RawFormat;
  int sW = 0, sH = 0;

  //按比例缩放
  Size tem_size = new Size(iSource.Width, iSource.Height);

  if (tem_size.Width > dHeight || tem_size.Width > dWidth)
  {
    if ((tem_size.Width * dHeight) > (tem_size.Width * dWidth))
    {
      sW = dWidth;
      sH = (dWidth * tem_size.Height) / tem_size.Width;
    }
    else
    {
      sH = dHeight;
      sW = (tem_size.Width * dHeight) / tem_size.Height;
    }
  }
  else
  {
    sW = tem_size.Width;
    sH = tem_size.Height;
  }

  Bitmap ob = new Bitmap(dWidth, dHeight);
  Graphics g = Graphics.FromImage(ob);

  g.Clear(Color.WhiteSmoke);
  g.CompositingQuality = CompositingQuality.HighQuality;
  g.SmoothingMode = SmoothingMode.HighQuality;
  g.InterpolationMode = InterpolationMode.HighQualityBicubic;

  g.DrawImage(iSource, new Rectangle((dWidth - sW) / 2, (dHeight - sH) / 2, sW, sH), 0, 0, iSource.Width, iSource.Height, GraphicsUnit.Pixel);

  g.Dispose();
  //以下代码为保存图片时，设置压缩质量
  EncoderParameters ep = new EncoderParameters();
  long[] qy = new long[1];
  qy[0] = flag;//设置压缩的比例1-100
  EncoderParameter eParam = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, qy);
  ep.Param[0] = eParam;
  try
  {
    ImageCodecInfo[] arrayICI = ImageCodecInfo.GetImageEncoders();
    ImageCodecInfo jpegICIinfo = null;
    for (int x = 0; x < arrayICI.Length; x++)
    {
      if (arrayICI[x].FormatDescription.Equals("JPEG"))
      {
        jpegICIinfo = arrayICI[x];
        break;
      }
    }
    if (jpegICIinfo != null)
    {
      ob.Save(dFile, jpegICIinfo, ep);//dFile是压缩后的新路径
    }
    else
    {
      ob.Save(dFile, tFormat);
    }
    return true;
  }
  catch
  {
    return false;
  }
  finally
  {
    iSource.Dispose();
    ob.Dispose();
  }
} 

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持脚本之家。