///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 = @"D\XX.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