C# image processing examples (cropping, scaling, clarity, watermark)

using System; using System.Collections.Generic; using System.Text; using System.IO; using System.Drawing; using System.Drawing.Drawing2D; using System.Drawing.Imaging; namespace WuJian.Common { public class Image { #region 正方型裁剪并缩放 /// 
 /// 正方型裁剪 /// 以图片中心为轴心，截取正方型，然后等比缩放 /// 用于头像处理 /// 
 /// 吴剑 2012-08-08 /// 原图Stream对象 /// 缩略图存放地址 /// 指定的边长（正方型） /// 质量（范围0-100） public static void CutForSquare(System.IO.Stream fromFile, string fileSaveUrl, int side, int quality) { //创建目录 string dir = Path.GetDirectoryName(fileSaveUrl); if (!Directory.Exists(dir)) Directory.CreateDirectory(dir); //原始图片（获取原始图片创建对象，并使用流中嵌入的颜色管理信息） System.Drawing.Image initImage = System.Drawing.Image.FromStream(fromFile, true); //原图宽高均小于模版，不作处理，直接保存 if (initImage.Width <= side && initImage.Height <= side) { initImage.Save(fileSaveUrl, System.Drawing.Imaging.ImageFormat.Jpeg); } else { //原始图片的宽、高 int initWidth = initImage.Width; int initHeight = initImage.Height; //非正方型先裁剪为正方型 if (initWidth != initHeight) { //截图对象 System.Drawing.Image pickedImage = null; System.Drawing.Graphics pickedG = null; //宽大于高的横图 if (initWidth > initHeight) { //对象实例化 pickedImage = new System.Drawing.Bitmap(initHeight, initHeight); pickedG = System.Drawing.Graphics.FromImage(pickedImage); //设置质量 pickedG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic; pickedG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; //定位 Rectangle fromR = new Rectangle((initWidth - initHeight) / 2, 0, initHeight, initHeight); Rectangle toR = new Rectangle(0, 0, initHeight, initHeight); //画图 pickedG.DrawImage(initImage, toR, fromR, System.Drawing.GraphicsUnit.Pixel); //重置宽 initWidth = initHeight; } //高大于宽的竖图 else { //对象实例化 pickedImage = new System.Drawing.Bitmap(initWidth, initWidth); pickedG = System.Drawing.Graphics.FromImage(pickedImage); //设置质量 pickedG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic; pickedG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; //定位 Rectangle fromR = new Rectangle(0, (initHeight - initWidth) / 2, initWidth, initWidth); Rectangle toR = new Rectangle(0, 0, initWidth, initWidth); //画图 pickedG.DrawImage(initImage, toR, fromR, System.Drawing.GraphicsUnit.Pixel); //重置高 initHeight = initWidth; } //将截图对象赋给原图 initImage = (System.Drawing.Image)pickedImage.Clone(); //释放截图资源 pickedG.Dispose(); pickedImage.Dispose(); } //缩略图对象 System.Drawing.Image resultImage = new System.Drawing.Bitmap(side, side); System.Drawing.Graphics resultG = System.Drawing.Graphics.FromImage(resultImage); //设置质量 resultG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic; resultG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; //用指定背景色清空画布 resultG.Clear(Color.White); //绘制缩略图 resultG.DrawImage(initImage, new System.Drawing.Rectangle(0, 0, side, side), new System.Drawing.Rectangle(0, 0, initWidth, initHeight), System.Drawing.GraphicsUnit.Pixel); //关键质量控制 //获取系统编码类型数组,包含了jpeg,bmp,png,gif,tiff ImageCodecInfo[] icis = ImageCodecInfo.GetImageEncoders(); ImageCodecInfo ici = null; foreach (ImageCodecInfo i in icis) { if (i.MimeType == "image/jpeg" || i.MimeType == "image/bmp" || i.MimeType == "image/png" || i.MimeType == "image/gif") { ici = i; } } EncoderParameters ep = new EncoderParameters(1); ep.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, (long)quality); //保存缩略图 resultImage.Save(fileSaveUrl, ici, ep); //释放关键质量控制所用资源 ep.Dispose(); //释放缩略图资源 resultG.Dispose(); resultImage.Dispose(); //释放原始图片资源 initImage.Dispose(); } } #endregion #region 自定义裁剪并缩放 /// 
 /// 指定长宽裁剪 /// 按模版比例最大范围的裁剪图片并缩放至模版尺寸 /// 
 /// 吴剑 2012-08-08 /// 原图Stream对象 /// 保存路径 /// 最大宽(单位:px) /// 最大高(单位:px) /// 质量（范围0-100） public static void CutForCustom(System.IO.Stream fromFile, string fileSaveUrl, int maxWidth, int maxHeight, int quality) { //从文件获取原始图片，并使用流中嵌入的颜色管理信息 System.Drawing.Image initImage = System.Drawing.Image.FromStream(fromFile, true); //原图宽高均小于模版，不作处理，直接保存 if (initImage.Width <= maxWidth && initImage.Height <= maxHeight) { initImage.Save(fileSaveUrl, System.Drawing.Imaging.ImageFormat.Jpeg); } else { //模版的宽高比例 double templateRate = (double)maxWidth / maxHeight; //原图片的宽高比例 double initRate = (double)initImage.Width / initImage.Height; //原图与模版比例相等，直接缩放 if (templateRate == initRate) { //按模版大小生成最终图片 System.Drawing.Image templateImage = new System.Drawing.Bitmap(maxWidth, maxHeight); System.Drawing.Graphics templateG = System.Drawing.Graphics.FromImage(templateImage); templateG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High; templateG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; templateG.Clear(Color.White); templateG.DrawImage(initImage, new System.Drawing.Rectangle(0, 0, maxWidth, maxHeight), new System.Drawing.Rectangle(0, 0, initImage.Width, initImage.Height), System.Drawing.GraphicsUnit.Pixel); templateImage.Save(fileSaveUrl, System.Drawing.Imaging.ImageFormat.Jpeg); } //原图与模版比例不等，裁剪后缩放 else { //裁剪对象 System.Drawing.Image pickedImage = null; System.Drawing.Graphics pickedG = null; //定位 Rectangle fromR = new Rectangle(0, 0, 0, 0);//原图裁剪定位 Rectangle toR = new Rectangle(0, 0, 0, 0);//目标定位 //宽为标准进行裁剪 if (templateRate > initRate) { //裁剪对象实例化 pickedImage = new System.Drawing.Bitmap(initImage.Width, (int)System.Math.Floor(initImage.Width / templateRate)); pickedG = System.Drawing.Graphics.FromImage(pickedImage); //裁剪源定位 fromR.X = 0; fromR.Y = (int)System.Math.Floor((initImage.Height - initImage.Width / templateRate) / 2); fromR.Width = initImage.Width; fromR.Height = (int)System.Math.Floor(initImage.Width / templateRate); //裁剪目标定位 toR.X = 0; toR.Y = 0; toR.Width = initImage.Width; toR.Height = (int)System.Math.Floor(initImage.Width / templateRate); } //高为标准进行裁剪 else { pickedImage = new System.Drawing.Bitmap((int)System.Math.Floor(initImage.Height * templateRate), initImage.Height); pickedG = System.Drawing.Graphics.FromImage(pickedImage); fromR.X = (int)System.Math.Floor((initImage.Width - initImage.Height * templateRate) / 2); fromR.Y = 0; fromR.Width = (int)System.Math.Floor(initImage.Height * templateRate); fromR.Height = initImage.Height; toR.X = 0; toR.Y = 0; toR.Width = (int)System.Math.Floor(initImage.Height * templateRate); toR.Height = initImage.Height; } //设置质量 pickedG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic; pickedG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; //裁剪 pickedG.DrawImage(initImage, toR, fromR, System.Drawing.GraphicsUnit.Pixel); //按模版大小生成最终图片 System.Drawing.Image templateImage = new System.Drawing.Bitmap(maxWidth, maxHeight); System.Drawing.Graphics templateG = System.Drawing.Graphics.FromImage(templateImage); templateG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High; templateG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; templateG.Clear(Color.White); templateG.DrawImage(pickedImage, new System.Drawing.Rectangle(0, 0, maxWidth, maxHeight), new System.Drawing.Rectangle(0, 0, pickedImage.Width, pickedImage.Height), System.Drawing.GraphicsUnit.Pixel); //关键质量控制 //获取系统编码类型数组,包含了jpeg,bmp,png,gif,tiff ImageCodecInfo[] icis = ImageCodecInfo.GetImageEncoders(); ImageCodecInfo ici = null; foreach (ImageCodecInfo i in icis) { if (i.MimeType == "image/jpeg" || i.MimeType == "image/bmp" || i.MimeType == "image/png" || i.MimeType == "image/gif") { ici = i; } } EncoderParameters ep = new EncoderParameters(1); ep.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, (long)quality); //保存缩略图 templateImage.Save(fileSaveUrl, ici, ep); //templateImage.Save(fileSaveUrl, System.Drawing.Imaging.ImageFormat.Jpeg); //释放资源 templateG.Dispose(); templateImage.Dispose(); pickedG.Dispose(); pickedImage.Dispose(); } } //释放资源 initImage.Dispose(); } #endregion #region 等比缩放 /// 
 /// 图片等比缩放 /// 
 /// 吴剑 2012-08-08 /// 原图Stream对象 /// 缩略图存放地址 /// 指定的最大宽度 /// 指定的最大高度 /// 水印文字(为""表示不使用水印) /// 水印图片路径(为""表示不使用水印) public static void ZoomAuto(System.IO.Stream fromFile, string savePath, System.Double targetWidth, System.Double targetHeight, string watermarkText, string watermarkImage) { //创建目录 string dir = Path.GetDirectoryName(savePath); if (!Directory.Exists(dir)) Directory.CreateDirectory(dir); //原始图片（获取原始图片创建对象，并使用流中嵌入的颜色管理信息） System.Drawing.Image initImage = System.Drawing.Image.FromStream(fromFile, true); //原图宽高均小于模版，不作处理，直接保存 if (initImage.Width <= targetWidth && initImage.Height <= targetHeight) { //文字水印 if (watermarkText != "") { using (System.Drawing.Graphics gWater = System.Drawing.Graphics.FromImage(initImage)) { System.Drawing.Font fontWater = new Font("黑体", 10); System.Drawing.Brush brushWater = new SolidBrush(Color.White); gWater.DrawString(watermarkText, fontWater, brushWater, 10, 10); gWater.Dispose(); } } //透明图片水印 if (watermarkImage != "") { if (File.Exists(watermarkImage)) { //获取水印图片 using (System.Drawing.Image wrImage = System.Drawing.Image.FromFile(watermarkImage)) { //水印绘制条件：原始图片宽高均大于或等于水印图片 if (initImage.Width >= wrImage.Width && initImage.Height >= wrImage.Height) { Graphics gWater = Graphics.FromImage(initImage); //透明属性 ImageAttributes imgAttributes = new ImageAttributes(); ColorMap colorMap = new ColorMap(); colorMap.OldColor = Color.FromArgb(255, 0, 255, 0); colorMap.NewColor = Color.FromArgb(0, 0, 0, 0); ColorMap[] remapTable = { colorMap }; imgAttributes.SetRemapTable(remapTable, ColorAdjustType.Bitmap); float[][] colorMatrixElements = { new float[] {1.0f, 0.0f, 0.0f, 0.0f, 0.0f}, new float[] {0.0f, 1.0f, 0.0f, 0.0f, 0.0f}, new float[] {0.0f, 0.0f, 1.0f, 0.0f, 0.0f}, new float[] {0.0f, 0.0f, 0.0f, 0.5f, 0.0f},//透明度:0.5 new float[] {0.0f, 0.0f, 0.0f, 0.0f, 1.0f} }; ColorMatrix wmColorMatrix = new ColorMatrix(colorMatrixElements); imgAttributes.SetColorMatrix(wmColorMatrix, ColorMatrixFlag.Default, ColorAdjustType.Bitmap); gWater.DrawImage(wrImage, new Rectangle(initImage.Width - wrImage.Width, initImage.Height - wrImage.Height, wrImage.Width, wrImage.Height), 0, 0, wrImage.Width, wrImage.Height, GraphicsUnit.Pixel, imgAttributes); gWater.Dispose(); } wrImage.Dispose(); } } } //保存 initImage.Save(savePath, System.Drawing.Imaging.ImageFormat.Jpeg); } else { //缩略图宽、高计算 double newWidth = initImage.Width; double newHeight = initImage.Height; //宽大于高或宽等于高（横图或正方） if (initImage.Width > initImage.Height || initImage.Width == initImage.Height) { //如果宽大于模版 if (initImage.Width > targetWidth) { //宽按模版，高按比例缩放 newWidth = targetWidth; newHeight = initImage.Height * (targetWidth / initImage.Width); } } //高大于宽（竖图） else { //如果高大于模版 if (initImage.Height > targetHeight) { //高按模版，宽按比例缩放 newHeight = targetHeight; newWidth = initImage.Width * (targetHeight / initImage.Height); } } //生成新图 //新建一个bmp图片 System.Drawing.Image newImage = new System.Drawing.Bitmap((int)newWidth, (int)newHeight); //新建一个画板 System.Drawing.Graphics newG = System.Drawing.Graphics.FromImage(newImage); //设置质量 newG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic; newG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; //置背景色 newG.Clear(Color.White); //画图 newG.DrawImage(initImage, new System.Drawing.Rectangle(0, 0, newImage.Width, newImage.Height), new System.Drawing.Rectangle(0, 0, initImage.Width, initImage.Height), System.Drawing.GraphicsUnit.Pixel); //文字水印 if (watermarkText != "") { using (System.Drawing.Graphics gWater = System.Drawing.Graphics.FromImage(newImage)) { System.Drawing.Font fontWater = new Font("宋体", 10); System.Drawing.Brush brushWater = new SolidBrush(Color.White); gWater.DrawString(watermarkText, fontWater, brushWater, 10, 10); gWater.Dispose(); } } //透明图片水印 if (watermarkImage != "") { if (File.Exists(watermarkImage)) { //获取水印图片 using (System.Drawing.Image wrImage = System.Drawing.Image.FromFile(watermarkImage)) { //水印绘制条件：原始图片宽高均大于或等于水印图片 if (newImage.Width >= wrImage.Width && newImage.Height >= wrImage.Height) { Graphics gWater = Graphics.FromImage(newImage); //透明属性 ImageAttributes imgAttributes = new ImageAttributes(); ColorMap colorMap = new ColorMap(); colorMap.OldColor = Color.FromArgb(255, 0, 255, 0); colorMap.NewColor = Color.FromArgb(0, 0, 0, 0); ColorMap[] remapTable = { colorMap }; imgAttributes.SetRemapTable(remapTable, ColorAdjustType.Bitmap); float[][] colorMatrixElements = { new float[] {1.0f, 0.0f, 0.0f, 0.0f, 0.0f}, new float[] {0.0f, 1.0f, 0.0f, 0.0f, 0.0f}, new float[] {0.0f, 0.0f, 1.0f, 0.0f, 0.0f}, new float[] {0.0f, 0.0f, 0.0f, 0.5f, 0.0f},//透明度:0.5 new float[] {0.0f, 0.0f, 0.0f, 0.0f, 1.0f} }; ColorMatrix wmColorMatrix = new ColorMatrix(colorMatrixElements); imgAttributes.SetColorMatrix(wmColorMatrix, ColorMatrixFlag.Default, ColorAdjustType.Bitmap); gWater.DrawImage(wrImage, new Rectangle(newImage.Width - wrImage.Width, newImage.Height - wrImage.Height, wrImage.Width, wrImage.Height), 0, 0, wrImage.Width, wrImage.Height, GraphicsUnit.Pixel, imgAttributes); gWater.Dispose(); } wrImage.Dispose(); } } } //保存缩略图 newImage.Save(savePath, System.Drawing.Imaging.ImageFormat.Jpeg); //释放资源 newG.Dispose(); newImage.Dispose(); initImage.Dispose(); } } #endregion #region 其它 /// 
 /// 判断文件类型是否为WEB格式图片 /// (注：JPG,GIF,BMP,PNG) /// 
 /// HttpPostedFile.ContentType ///  public static bool IsWebImage(string contentType) { if (contentType == "image/pjpeg" || contentType == "image/jpeg" || contentType == "image/gif" || contentType == "image/bmp" || contentType == "image/png") { return true; } else { return false; } } #endregion }//end class }