/// <param name="dWidth">要生成的宽度</param> /// <param name="dHeight">要生成的高度</param> /// <param name="flag">生成图片质量，1-100</param> /// <param name="inputStream">输入图片流</param> /// <param name="outStream">输出图片流</param> public static void CompressImgByte ( int dWidth , int dHeight , Stream inputStream , Stream outStream , int flag = 80 , string arg = null ) inputStream . Position = 0 ; System . Drawing . Image iSource = System . Drawing . Image . FromStream ( inputStream ) ; var prop = iSource . PropertyItems . FirstOrDefault ( x => x . Id == 274 ) ; if ( prop != null ) //读取旋转方向 byte [ ] buffed = prop . Value ; StringBuilder sbv = new StringBuilder ( ) ; foreach ( var byteValue in buffed ) sbv . Append ( byteValue . ToString ( "x2" ) ) ; string value2 = sbv . ToString ( ) ; //Console.WriteLine($"图片id {arg} 图片274里面的值>" + value2);//linux测试 //windows获取到旋转的值为0600，linux旋转值为0006 if ( value2 . Equals ( "0006" ) || value2 . Equals ( "0600" ) ) //未做任何操作，此缩略图会自动逆时针旋转90度 //下面操作纠正旋转，让其顺时针旋转90度，让图片回正 iSource . RotateFlip ( RotateFlipType . Rotate90FlipNone ) ; System . Drawing . Imaging . ImageFormat tFormat = iSource . RawFormat ; //按比例缩放 if ( dWidth > 0 && iSource . Width > dWidth && iSource . Width > iSource . Height ) dHeight = dWidth * iSource . Height / iSource . Width ; else if ( dWidth > 0 && dHeight == 0 && iSource . Width > dWidth ) dHeight = dWidth * iSource . Height / iSource . Width ; else if ( dWidth == 0 && dHeight > 0 && iSource . Width > iSource . Height ) dWidth = dHeight * iSource . Width / iSource . Height ; else if ( dHeight > iSource . Height || dWidth > iSource . Width ) dWidth = iSource . Width ; dHeight = iSource . Height ; else if ( dHeight > 0 && iSource . Width < iSource . Height ) dWidth = dHeight * iSource . Width / iSource . Height ; dWidth = iSource . Width ; dHeight = iSource . Height ; Bitmap ob = new Bitmap ( dWidth , dHeight ) ; //ob.SetResolution(72,72); Graphics g = Graphics . FromImage ( ob ) ; //清空画布并以透明背景色填充 g . Clear ( System . Drawing . Color . Transparent ) ; g . CompositingQuality = System . Drawing . Drawing2D . CompositingQuality . HighQuality ; g . SmoothingMode = System . Drawing . Drawing2D . SmoothingMode . HighQuality ; g . InterpolationMode = System . Drawing . Drawing2D . InterpolationMode . HighQualityBicubic ; g . DrawImage ( iSource , new Rectangle ( 0 , 0 , dWidth , dHeight ) , 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 System . Drawing . Imaging . EncoderParameters ep = new System . Drawing . Imaging . EncoderParameters ( ) ; long [ ] qy = new long [ 1 ] ; qy [ 0 ] = flag ; //设置压缩的比例1-100 System . Drawing . Imaging . EncoderParameter eParam = new System . Drawing . Imaging . EncoderParameter ( System . Drawing . Imaging . Encoder . Quality , qy ) ; ep . Param [ 0 ] = eParam ; System . Drawing . Imaging . ImageCodecInfo [ ] arrayICI = System . Drawing . Imaging . ImageCodecInfo . GetImageEncoders ( ) ; System . Drawing . Imaging . ImageCodecInfo jpegICIinfo = arrayICI . FirstOrDefault ( x => x . FormatDescription . Equals ( "JPEG" ) ) ; if ( jpegICIinfo != null ) //ob.Save("d://" + DateTime.Now.Ticks + ".jpg", jpegICIinfo, ep); ob . Save ( outStream , jpegICIinfo , ep ) ; //dFile是压缩后的新路径 ob . Save ( outStream , tFormat ) ; catch ( Exception ex ) string msg = ex . Message ; Console . WriteLine ( msg ) ; finally iSource . Dispose ( ) ; ob . Dispose ( ) ; /// <summary> /// (推荐)生成缩略图，图片流输入，输出图片流 /// </summary> /// <param name="dWidth">要生成的宽度</param> /// <param name="dHeight">要生成的高度</param> /// <param name="filePath">输入文件路径</param> /// <param name="outFilePath">输出保存文件路径</param> /// <param name="flag">生成的图片质量，0-100，默认80</param> public static void CompressImgFile ( int dWidth , int dHeight , string filePath , string outFilePath , int flag = 80 ) System . Drawing . Image iSource = System . Drawing . Image . FromFile ( filePath ) ; //检测图片是否有旋转 foreach ( var item in iSource . PropertyItems ) //System.Diagnostics.Debug.WriteLine(item.Id); if ( item . Id == 274 ) //读取旋转方向 byte [ ] buffed = item . Value ; StringBuilder sbv = new StringBuilder ( ) ; foreach ( var byteValue in buffed ) sbv . Append ( byteValue . ToString ( "x2" ) ) ; //string value2 = string.Join("", buffed); string value2 = sbv . ToString ( ) ; System . Diagnostics . Debug . WriteLine ( "方向=" + value2 ) ; //windows获取到旋转的值为0600，linux旋转值为0006 if ( value2 . Equals ( "0006" ) || value2 . Equals ( "0600" ) ) //未做任何操作，此缩略图会自动逆时针旋转90度 //下面操作纠正旋转，让其顺时针旋转90度，让图片回正 iSource . RotateFlip ( RotateFlipType . Rotate90FlipNone ) ; break ; System . Drawing . Imaging . ImageFormat tFormat = iSource . RawFormat ; //按比例缩放 if ( dWidth > 0 && iSource . Width > dWidth && iSource . Width > iSource . Height ) dHeight = dWidth * iSource . Height / iSource . Width ; else if ( dWidth > 0 && dHeight == 0 && iSource . Width > dWidth ) dHeight = dWidth * iSource . Height / iSource . Width ; else if ( dWidth == 0 && dHeight > 0 && iSource . Width > iSource . Height ) dWidth = dHeight * iSource . Width / iSource . Height ; else if ( dHeight > iSource . Height || dWidth > iSource . Width ) dWidth = iSource . Width ; dHeight = iSource . Height ; else if ( dHeight > 0 && iSource . Width < iSource . Height ) dWidth = dHeight * iSource . Width / iSource . Height ; dWidth = iSource . Width ; dHeight = iSource . Height ; Bitmap ob = new Bitmap ( dWidth , dHeight ) ; //ob.SetResolution(72,72); Graphics g = Graphics . FromImage ( ob ) ; //清空画布并以透明背景色填充 g . Clear ( System . Drawing . Color . Transparent ) ; g . CompositingQuality = System . Drawing . Drawing2D . CompositingQuality . HighQuality ; g . SmoothingMode = System . Drawing . Drawing2D . SmoothingMode . HighQuality ; g . InterpolationMode = System . Drawing . Drawing2D . InterpolationMode . HighQualityBicubic ; g . DrawImage ( iSource , new Rectangle ( 0 , 0 , dWidth , dHeight ) , 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 System . Drawing . Imaging . EncoderParameters ep = new System . Drawing . Imaging . EncoderParameters ( ) ; long [ ] qy = new long [ 1 ] ; qy [ 0 ] = flag ; //设置压缩的比例1-100 System . Drawing . Imaging . EncoderParameter eParam = new System . Drawing . Imaging . EncoderParameter ( System . Drawing . Imaging . Encoder . Quality , qy ) ; ep . Param [ 0 ] = eParam ; System . Drawing . Imaging . ImageCodecInfo [ ] arrayICI = System . Drawing . Imaging . ImageCodecInfo . GetImageEncoders ( ) ; System . Drawing . Imaging . ImageCodecInfo jpegICIinfo = null ; // string imgExtend = tFormat.ToString().ToUpper(); string imgExtend = "JPEG" ; for ( int x = 0 ; x < arrayICI . Length ; x ++ ) if ( arrayICI [ x ] . FormatDescription . Equals ( imgExtend ) ) jpegICIinfo = arrayICI [ x ] ; break ; if ( jpegICIinfo != null ) ob . Save ( outFilePath , jpegICIinfo , ep ) ; //dFile是压缩后的新路径 ob . Save ( outFilePath , tFormat ) ; catch ( Exception ex ) string msg = ex . Message ; Console . WriteLine ( msg ) ; finally iSource . Dispose ( ) ; ob . Dispose ( ) ;

 string fileInput = "E:\\测试图片\\2023_11_07_155548.3179.jpg";
 string outFile = "E:\\测试图片\\2023_11_07_155548.3179_c2222.jpg";
 //ImageHandle.CompressImgFile(1300, 1300, fileInput, outFile);
 var fileByter= File.ReadAllBytes(fileInput);
 System.IO.Stream inStream = new System.IO.MemoryStream();
 inStream.Write(fileByter, 0, fileByter.Length);
 System.IO.Stream outStream = new System.IO.MemoryStream();
 //执行压缩图片
 ImageHandle.CompressImgByte(1300, 1300, inStream, outStream);
 outStream.Position = 0;
 //压缩后的图片
 byte[] fileYaSuoByte = new byte[outStream.Length];
 outStream.Read(fileYaSuoByte, 0, (int)outStream.Length);
 File.WriteAllBytes(outFile,fileYaSuoByte);
				
说明：该类也来源于网上，只不过我对其进行了一些改动。原类生成的缩略图的问题在于：高或者宽可能会大于需求值。比如，我需要的图片宽为150，高为120，当原图
 * 高为150，宽为150或差距不大时，生成的图片不会有变化，即也是高150，宽150，这样，当把这些图片显示到网页上的高为150，高为120的规格里的时候，高方向就会
 * 被撑破 。
 * 修改后：当出现这种情况后，图片会按最小边进行缩略，即如果原图高为150，宽为150，要求宽150，高120，那生成的图片就是120*120。总之，就是不会出现网页被
 * 撑破的或变形的情况。
 * 使用方法：
 * zoomImage.MakeZoomImage(原文件名, 缩略图文件名, 缩略图宽,缩略图高 , 模式);
 * 如：zoomImage.MakeZoomImage(Server.MapPath("~/uploads/")  + bigFilename, Server.MapPath("~/uploads/")  + smallFileName1, 150, 120, "HW");




    

//将图片保存在内存中
Emgu.CV.Util.VectorOfByte buf = new Emgu.CV.Util.VectorOfByte();
CvInvoke.Imencode(".png", mat, buf);
byte[] vs = buf.ToArray
				
根据一个Image的Url链接可以在浏览器中显示一个图片，如果要通过代码将图片保存在本地磁盘可以通过以下方式：
1、首先获取图片的二进制数组。
static public byte[] GetBytesFromUrl(string url)
byte[] b; 
HttpWebRequest myReq = (HttpWebRequest)WebReques...
        public void ProcessRequest(HttpContext context)
            context.Response.ContentType = "text/plain";
            //接受用户上传
				
在asp.net中，上传图片功能或者是常用的，生成缩略图也是常用的。baidu或者google，c#的方法也是很多的，但是一用却发现缩略图不清晰啊，缩略图片太大之类的事情，下面是我在处理图片上的代码，效果不错，所以拿出来分享，(效果能达到一些绘图软件的效果)
代码如下：
using System;using System.Drawing;
using System.Drawing.Drawi
参数解答：
1 源图路径：是指你那张图的物理路径，如：@"E:\2001\1.jpg";
2 缩略图路径： 是指图片已生成缩略图后应放的路径，如：@"E:2002\1_min.jpg";
3 缩略图宽度：是指想要生成的缩略图的宽度，...
				
背景：在地图瓦片的请求过程中，可能存在瓦片遗失的情况，这时候需要在地图上展示默认的瓦片图片，之前在前端相关地图包中去实现，现在在后台实现当请求瓦片失败时，返回默认的瓦片图片，且支持默认图片配置。
1.创建.net 5 Web项目
2.引入Microsoft.Extensions.Configuration，用于读取appsettings.json
3.新建中间件类DefaultImageMiddleware
   public class DefaultImageMiddleware
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