c#图片压缩

///调用事例

private void button5_Click(object sender, EventArgs e)
{
string pathPerc = @"E:XX.jpg";//保存图片地址,名称和格式
string source = @"DXX.jpg";//图片源文件路径
getThumImage(source, 50, 2, pathPerc);//quality,multiple越小压缩图片越大

}

/**/
/// <summary>
/// 生成缩略图
/// </summary>
/// <param name="sourceFile">原始图片文件</param>
/// <param name="quality">质量压缩比</param>
/// <param name="multiple">收缩倍数</param>
/// <param name="outputFile">输出文件名</param>
/// <returns>成功返回true,失败则返回false</returns>
public static bool getThumImage(String sourceFile, long quality, int multiple, String outputFile)
{
try
{
long imageQuality = quality;
Bitmap sourceImage = new Bitmap(sourceFile);
ImageCodecInfo myImageCodecInfo = GetEncoderInfo("image/jpeg");
System.Drawing.Imaging.Encoder myEncoder = System.Drawing.Imaging.Encoder.Quality;
EncoderParameters myEncoderParameters = new EncoderParameters(1);
EncoderParameter myEncoderParameter = new EncoderParameter(myEncoder, imageQuality);
myEncoderParameters.Param[0] = myEncoderParameter;
float xWidth = sourceImage.Width;
float yWidth = sourceImage.Height;
Bitmap newImage = new Bitmap((int)(xWidth / multiple), (int)(yWidth / multiple));
Graphics g = Graphics.FromImage(newImage);

g.DrawImage(sourceImage, 0, 0, xWidth / multiple, yWidth / multiple);
g.Dispose();
newImage.Save(outputFile, myImageCodecInfo, myEncoderParameters);
return true;
}
catch (Exception ex)
{
return false;
}
}

private static ImageCodecInfo GetEncoderInfo(String mimeType)
{
int j;
ImageCodecInfo[] encoders;
encoders = ImageCodecInfo.GetImageEncoders();
for (j = 0; j < encoders.Length; ++j)
{
if (encoders[j].MimeType == mimeType)
return encoders[j];
}
return null;
}

原文来至:http://blog.csdn.net/szstephenzhou/article/details/38900345