实现一（只改变图片质量，不改变图片尺寸）：
/// <summary> /// 图片压缩(降低质量以减小文件的大小)，不用保存到某个路径 /// </summary> /// <param name="srcBitmap">传入的Bitmap对象</param> /// <param name="destStream">压缩后的Stream对象</param> /// <param name="level">压缩等级，0到100，0 最差质量，100 最佳</param> public static void Compress(Bitmap srcBitmap, Stream destStream, long level) { ImageCodecInfo myImageCodecInfo; Encoder myEncoder; EncoderParameter myEncoderParameter; EncoderParameters myEncoderParameters; myImageCodecInfo = GetEncoderInfo("image/jpeg"); //得到一个表示JPEG编码的 imagecodecinfo 对象image/jpeg myEncoder = Encoder.Quality; //根据质量参数类别的全局唯一标识符创建并初始化一个编码器对象 //创建encoderparameters对象。 //encoderparameters 对象包含一个encoderparameter对象数组。在本例中，数组中只有一个encoderparameter对象。 myEncoderParameters = new EncoderParameters(1); // Save the bitmap as a JPEG file with 给定的 quality level myEncoderParameter = new EncoderParameter(myEncoder, level); myEncoderParameters.Param[0] = myEncoderParameter; srcBitmap.Save(destStream, myImageCodecInfo, myEncoderParameters); } /// <summary> /// 图片压缩(降低质量以减小文件的大小)，保存在某个路径 /// </summary> /// <param name="srcBitMap">传入的Bitmap对象</param> /// <param name="destFile">压缩后的图片保存路径</param> /// <param name="level">压缩等级，0到100，0 最差质量，100 最佳</param> public static void Compress(Bitmap srcBitMap, string destFile, long level) { Stream s = new FileStream(destFile, FileMode.Create); Compress(srcBitMap, s, level); s.Close(); } /// <summary> /// 获取图片编码类型信息：返回 ImageCodecInfo 的 GetEncoderInfo 方法 /// </summary> /// <param name="mimeType">编码类型</param> /// <returns></returns> private static ImageCodecInfo GetEncoderInfo(String mimeType) { ImageCodecInfo[] encoders = ImageCodecInfo.GetImageEncoders(); foreach (ImageCodecInfo ici in encoders) { if (ici.MimeType.Equals(mimeType)) return ici; } return null; }
实现二（只改变图片质量，不改变图片尺寸）：
/// <summary> /// 压缩图片 /// </summary> /// <param name="filePath">要压缩的图片的路径</param> /// <param name="filePath_ystp">压缩后的图片的路径</param> public void ystp(string filePath, string filePath_ystp) { Bitmap bmp = null; //Bitmap ImageCodecInfo ici = null; //ImageCoderInfo Encoder ecd = null; //Encoder EncoderParameter ept = null; //EncoderParameter EncoderParameters eptS = null; //EncoderParameters try { bmp = new Bitmap(filePath); ici = this.getImageCoderInfo("image/jpeg"); //图片编码信息 ecd = Encoder.Quality; //根据质量参数类别的全局唯一标识符创建并初始化一个编码器对象 eptS = new EncoderParameters(1); ept = new EncoderParameter(ecd, 10L); eptS.Param[0] = ept; bmp.Save(filePath_ystp, ici, eptS); } catch (Exception ex) { throw new Exception(ex.Message); } finally { bmp.Dispose(); ept.Dispose(); eptS.Dispose(); } } /// <summary> /// 获取图片编码类型信息 /// </summary> /// <param name="coderType">编码类型</param> /// <returns>ImageCodecInfo</returns> private ImageCodecInfo getImageCoderInfo(string coderType) { ImageCodecInfo[] iciS = ImageCodecInfo.GetImageEncoders(); ImageCodecInfo retIci = null; foreach (ImageCodecInfo ici in iciS) { if (ici.MimeType.Equals(coderType)) retIci = ici; } return retIci; }
实现三（可同时实现质量压缩和尺寸按倍数收缩）：
#region getThumImage /**/ /// <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 { return false; } } #endregion getThumImage /**/ /// <summary> /// 获取图片编码信息 /// </summary> 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; }
实现四（可按指定尺寸进行压缩）：
/// <summary> /// 压缩图片 /// </summary> /// <returns></returns> public string ResizePic() { #region 压缩图片开始 bool IsImgFile = true; //判断是否为图片文件 string filePathName = "123"; //文件存储的路径（文件夹名称） string fileName = "a.jpg"; //上传文件的原始名称 string fileSysName = DateTime.Now.ToString("yyyyMMddHHmmssfff") + "_" + fileName; //修改后的文件名称 string filePath = ""; //文件路径 string strImgPath = "/fileupload/"; //上传路径 if (IsImgFile) { int maxWidth = 600; //图片宽度最大限制 int maxHeight = 400; //图片高度最大限制 System.Drawing.Image imgPhoto = System.Drawing.Image.FromFile(Server.MapPath(strImgPath) + filePathName + "/" + fileSysName); int imgWidth = imgPhoto.Width; int imgHeight = imgPhoto.Height; if (imgWidth > imgHeight) //如果宽度超过高度以宽度为准来压缩 { if (imgWidth > maxWidth) //如果图片宽度超过限制 { float toImgWidth = maxWidth; //图片压缩后的宽度 float toImgHeight = imgHeight / (float)(imgWidth / toImgWidth); //图片压缩后的高度 System.Drawing.Bitmap img = new System.Drawing.Bitmap(imgPhoto, int.Parse(toImgWidth.ToString()), int.Parse(toImgHeight.ToString())); string strResizePicName = Server.MapPath(strImgPath) + filePathName + "/_small_" + fileSysName; img.Save(strResizePicName); //保存压缩后的图片 filePath = strImgPath + filePathName + "/_small_" + fileSysName; //返回压缩后的图片路径 } } else { if (imgHeight > maxHeight) { float toImgHeight1 = maxHeight; float toImgWidth1 = imgWidth / (float)(imgHeight / toImgHeight1); System.Drawing.Bitmap img = new System.Drawing.Bitmap(imgPhoto, int.Parse(toImgWidth1.ToString()), int.Parse(toImgHeight1.ToString())); string strResizePicName = Server.MapPath(strImgPath) + filePathName + "/_small_" + fileSysName; img.Save(strResizePicName); filePath = strImgPath + filePathName + "/_small_" + fileSysName; } } } return filePath; #endregion }
实现五（高质量压缩图）：
第一步为画布描绘时的质量设置，第二步为保存图片时JPEG压缩的设置。
private Size NewSize(int maxWidth, int maxHeight, int width, int height) { double w = 0.0; double h = 0.0; double sw = Convert.ToDouble(width); double sh = Convert.ToDouble(height); double mw = Convert.ToDouble(maxWidth); double mh = Convert.ToDouble(maxHeight); if ( sw < mw && sh < mh ) { w = sw; h = sh; } else if ( (sw/sh) > (mw/mh) ) { w = maxWidth; h = (w * sh)/sw; } else { h = maxHeight; w = (h * sw)/sh; } return new Size(Convert.ToInt32(w), Convert.ToInt32(h)); } private void SendSmallImage(string fileName, int maxWidth, int maxHeight) { System.Drawing.Image img = System.Drawing.Image.FromFile(Server.MapPath(fileName)); System.Drawing.Imaging.ImageFormat thisFormat = img.RawFormat; Size newSize = NewSize(maxWidth, maxHeight, img.Width, img.Height); Bitmap outBmp = new Bitmap(newSize.Width, newSize.Height); Graphics g = Graphics.FromImage(outBmp); // 设置画布的描绘质量 g.CompositingQuality = CompositingQuality.HighQuality; g.SmoothingMode = SmoothingMode.HighQuality; g.InterpolationMode = InterpolationMode.HighQualityBicubic; g.DrawImage(img, new Rectangle(0, 0, newSize.Width, newSize.Height), 0, 0, img.Width, img.Height, GraphicsUnit.Pixel); g.Dispose(); if (thisFormat.Equals(ImageFormat.Gif)) { Response.ContentType = "image/gif"; } else { Response.ContentType = "image/jpeg"; } // 以下代码为保存图片时，设置压缩质量 EncoderParameters encoderParams = new EncoderParameters(); long[] quality = new long[1]; quality[0] = 100; EncoderParameter encoderParam = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, quality); encoderParams.Param[0] = encoderParam; //获得包含有关内置图像编码解码器的信息的ImageCodecInfo 对象。 ImageCodecInfo[] arrayICI = ImageCodecInfo.GetImageEncoders(); ImageCodecInfo jpegICI = null; for (int x = 0; x < arrayICI.Length; x++) { if (arrayICI[x].FormatDescription.Equals("JPEG")) { jpegICI = arrayICI[x];//设置JPEG编码 break; } } if (jpegICI != null) { outBmp.Save(Response.OutputStream, jpegICI, encoderParams); } else { outBmp.Save(Response.OutputStream, thisFormat); } img.Dispose(); outBmp.Dispose(); }
实现六（无损高质量压缩图片）：
/// 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(); } }
实现七（由java代码该编，还没改完）：
//1、质量压缩方法 private Bitmap compressImage(Bitmap image) { MemoryStream stream = new MemoryStream(); image.Save(stream, ImageFormat.Jpeg); //将图片以某种格式保存到流中 Compress(image, stream, 100); //质量压缩，这里100表示不压缩，把压缩后的数据存放到 stream 中 int options = 100; while (stream.ToArray().Length / 1024 > 100) { //循环判断如果压缩后图片是否大于100kb,大于继续压缩 stream.//重置stream即清空stream image.compress(Bitmap.CompressFormat.JPEG, options, stream);//这里压缩options%，把压缩后的数据存放到stream中 options -= 10;//每次都减少10 } ByteArrayInputStream isBm = new ByteArrayInputStream(baos.toByteArray());//把压缩后的数据baos存放到ByteArrayInputStream中 Bitmap bitmap = BitmapFactory.decodeStream(isBm, null, null);//把ByteArrayInputStream数据生成图片 return bitmap; } //2、按比例压缩方法，先图片大小再图片质量压缩（根据路径获取图片并压缩） private Bitmap getimage(String srcPath) { BitmapFactory.Options newOpts = new BitmapFactory.Options(); //开始读入图片，此时把options.inJustDecodeBounds 设回true了 newOpts.inJustDecodeBounds = true; Bitmap bitmap = BitmapFactory.decodeFile(srcPath, newOpts);//此时返回bm为空 newOpts.inJustDecodeBounds = false; int w = newOpts.outWidth; int h = newOpts.outHeight; //现在主流手机比较多是800*480分辨率，所以高和宽我们设置为 float hh = 800f;//这里设置高度为800f float ww = 480f;//这里设置宽度为480f //缩放比。由于是固定比例缩放，只用高或者宽其中一个数据进行计算即可 int be = 1;//be=1表示不缩放 if (w > h && w > ww) {//如果宽度大的话根据宽度固定大小缩放 be = (int)(newOpts.outWidth / ww); } else if (w < h && h > hh) {//如果高度高的话根据宽度固定大小缩放 be = (int)(newOpts.outHeight / hh); } if (be <= 0) be = 1; newOpts.inSampleSize = be;//设置缩放比例 //重新读入图片，注意此时已经把options.inJustDecodeBounds 设回false了 bitmap = BitmapFactory.decodeFile(srcPath, newOpts); return compressImage(bitmap);//压缩好比例大小后再进行质量压缩 } //3、按比例压缩方法，先图片大小再图片质量压缩（根据路径获取图片并压缩） private Bitmap comp(Bitmap image) { ByteArrayOutputStream baos = new ByteArrayOutputStream(); image.compress(Bitmap.CompressFormat.JPEG, 100, baos); if (baos.toByteArray().length / 1024 > 1024) {//判断如果图片大于1M,进行压缩避免在生成图片（BitmapFactory.decodeStream）时溢出 baos.reset();//重置baos即清空baos image.compress(Bitmap.CompressFormat.JPEG, 50, baos);//这里压缩50%，把压缩后的数据存放到baos中 } ByteArrayInputStream isBm = new ByteArrayInputStream(baos.toByteArray()); BitmapFactory.Options newOpts = new BitmapFactory.Options(); //开始读入图片，此时把options.inJustDecodeBounds 设回true了 newOpts.inJustDecodeBounds = true; Bitmap bitmap = BitmapFactory.decodeStream(isBm, null, newOpts); newOpts.inJustDecodeBounds = false; int w = newOpts.outWidth; int h = newOpts.outHeight; //现在主流手机比较多是800*480分辨率，所以高和宽我们设置为 float hh = 800f;//这里设置高度为800f float ww = 480f;//这里设置宽度为480f //缩放比。由于是固定比例缩放，只用高或者宽其中一个数据进行计算即可 int be = 1;//be=1表示不缩放 if (w > h && w > ww) {//如果宽度大的话根据宽度固定大小缩放 be = (int)(newOpts.outWidth / ww); } else if (w < h && h > hh) {//如果高度高的话根据宽度固定大小缩放 be = (int)(newOpts.outHeight / hh); } if (be <= 0) be = 1; newOpts.inSampleSize = be;//设置缩放比例 //重新读入图片，注意此时已经把options.inJustDecodeBounds 设回false了 isBm = new ByteArrayInputStream(baos.toByteArray()); bitmap = BitmapFactory.decodeStream(isBm, null, newOpts); return compressImage(bitmap);//压缩好比例大小后再进行质量压缩 }