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 

        /// <summary> 

        /// 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 

        /// </summary> 

        /// <remarks>吴剑 2012-08-08</remarks> 

        /// <param name="fromFile">原图Stream对象</param> 

        /// <param name="fileSaveUrl">缩略图存放地址</param> 

        /// <param name="side">指定的边长（正方型）</param> 

        /// <param name="quality">质量（范围0-100）</param> 

        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 

        /// <summary> 

        /// 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 

        /// </summary> 

        /// <remarks>吴剑 2012-08-08</remarks> 

        /// <param name="fromFile">原图Stream对象</param> 

        /// <param name="fileSaveUrl">保存路径</param> 

        /// <param name="maxWidth">最大宽(单位:px)</param> 

        /// <param name="maxHeight">最大高(单位:px)</param> 

        /// <param name="quality">质量（范围0-100）</param> 

        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 

        /// <summary> 

        /// 图片等比缩放 

        /// </summary> 

        /// <remarks>吴剑 2012-08-08</remarks> 

        /// <param name="fromFile">原图Stream对象</param> 

        /// <param name="savePath">缩略图存放地址</param> 

        /// <param name="targetWidth">指定的最大宽度</param> 

        /// <param name="targetHeight">指定的最大高度</param> 

        /// <param name="watermarkText">水印文字(为""表示不使用水印)</param> 

        /// <param name="watermarkImage">水印图片路径(为""表示不使用水印)</param> 

        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 

        /// <summary> 

        /// 判断文件类型是否为WEB格式图片 

        /// (注：JPG,GIF,BMP,PNG) 

        /// </summary> 

        /// <param name="contentType">HttpPostedFile.ContentType</param> 

        /// <returns></returns> 

        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 

}