[翻译]Asp.net生成高质量缩略图

原文：http://www.thebrainparasite.com/post/Creating-great-thumbnails-in-ASPNET.aspx

使用ASP.NET内置的功能创建缩略图是非常方便和容易实现的。

int width = 190;

int height = 190;

Bitmap source = new Bitmap("c:\someimage.gif");

System.Drawing.Image thumb = source.GetThumbnailImage(width,height,null,IntPtr.Zero);

public static Bitmap CreateThumbnail(Bitmap source, int thumbWi, int thumbHi, bool maintainAspect)

using (Graphics g = Graphics.FromImage(ret))

//Configure JPEG Compression Engine

System.Drawing.Imaging.EncoderParameters encoderParams = new System.Drawing.Imaging.EncoderParameters();

long[] quality = new long[1];

quality[0] = 75;

System.Drawing.Imaging.EncoderParameter encoderParam = new System.Drawing.Imaging.EncoderParameter(System.Drawing.Imaging.Encoder.Quality, quality);

encoderParams.Param[0] = encoderParam;

System.Drawing.Imaging.ImageCodecInfo[] arrayICI = System.Drawing.Imaging.ImageCodecInfo.GetImageEncoders();

System.Drawing.Imaging.ImageCodecInfo jpegICI = null;

for (int x = 0; x < arrayICI.Length; x++)

System.Drawing.Image myThumbnail = CreateThumbnail(myBitmap,Width,Height,false);

//Configure JPEG Compression Engine

System.Drawing.Imaging.EncoderParameters encoderParams = new System.Drawing.Imaging.EncoderParameters();

long[] quality = new long[1];

quality[0] = 75;

System.Drawing.Imaging.EncoderParameter encoderParam = new System.Drawing.Imaging.EncoderParameter(System.Drawing.Imaging.Encoder.Quality, quality);

encoderParams.Param[0] = encoderParam;

System.Drawing.Imaging.ImageCodecInfo[] arrayICI = System.Drawing.Imaging.ImageCodecInfo.GetImageEncoders();

System.Drawing.Imaging.ImageCodecInfo jpegICI = null;

for (int x = 0; x < arrayICI.Length; x++)

myThumbnail.Save(Path.Combine(SavePathThumb, fileName), jpegICI, encoderParams);

myThumbnail.Dispose();



(2.39k)

2.39K 大小 看起来依然很棒

结论和最后比较

这是最后三张缩略图从文件大小最大到最小的效果对比









最大 = 31.7k

未压缩重绘 = 10.5k (67% smaller)

压缩重绘 = 2.39k (92% smaller)

难以舍弃的结果啊，缩略图生成函数和JPEG压缩的源代码 在下边 ：

ThumbnailGenerator.cs (1.97 kb)

JPEGCompressionConfig.cs (969.00 bytes)