1. 程式人生 > >C#圖片處理3種高階應用(高縮圖清晰度、圖片剪裁、圖片水印)

C#圖片處理3種高階應用(高縮圖清晰度、圖片剪裁、圖片水印)

利用C#圖片處理的一些基本和高階應用,解決了顯示排版時想讓相片縮圖列表非常統一、整齊、和美觀,每張縮圖大小固定為120 x 90且不拉伸變形,使用者頭像讓縮圖比原圖更清晰,上傳的圖片下加一個半透明的LOGO水印等等要求。
高縮圖清晰度

之前一直認為縮圖不可能比原圖清晰,直到某天一位產品的同事給我看某網站的效果。於是開始尋找.NET下實現程式碼,仔細觀察縮圖確實比原圖更清晰了一些,但代價是縮圖檔案比原圖更大,所以如果你想讓一張佔滿顯示器螢幕的超大圖片更清晰,那麼圖片佔用空間和網路流量就必需考慮了,如果是網際網路應用,建議縮圖在200畫素以內的使用該方法。當然如果哪位有更好的程式碼即能讓圖片檔案大小變化不大又讓圖片更清晰還請分享。

圖片剪裁

演算法:以原圖中心作為裁剪中心,最大範圍的對原圖進行裁剪,然後對裁剪結果等比縮放。

圖片水印

 

詳細程式碼:

封裝了幾個通用的方法,如發現有BUG或漏洞還請及時指正。

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 正方型裁剪並縮放 /// <summary> /// 正方型裁剪 /// 以圖片中心為軸心,擷取正方型,然後等比縮放 /// 用於頭像處理 /// </summary> /// <remarks>吳劍 2012-08-08</remarks> /// <param name="fromFile">原圖Stream物件</param> /// <param name="fileSaveUrl">縮圖存放地址</param>
/// <param name="side">指定的邊長(正方型)</param> /// <param name="quality">質量(範圍0-100)</param> public static void CutForSquare(System.IO.Stream fromFile, string fileSaveUrl, int side, int quality) { //建立目錄 string dir = Path.GetDirectoryName(fileSaveUrl); if (!Directory.Exists(dir)) Directory.CreateDirectory(dir); //原始圖片(獲取原始圖片建立物件,並使用流中嵌入的顏色管理資訊) System.Drawing.Image initImage = System.Drawing.Image.FromStream(fromFile, true); //原圖寬高均小於模版,不作處理,直接儲存 if (initImage.Width <= side && initImage.Height <= side) { initImage.Save(fileSaveUrl, System.Drawing.Imaging.ImageFormat.Jpeg); } else { //原始圖片的寬、高 int initWidth = initImage.Width; int initHeight = initImage.Height; //非正方型先裁剪為正方型 if (initWidth != initHeight) { //截圖物件 System.Drawing.Image pickedImage = null; System.Drawing.Graphics pickedG = null; //寬大於高的橫圖 if (initWidth > initHeight) { //物件例項化 pickedImage = new System.Drawing.Bitmap(initHeight, initHeight); pickedG = System.Drawing.Graphics.FromImage(pickedImage); //設定質量 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); //畫圖 pickedG.DrawImage(initImage, toR, fromR, System.Drawing.GraphicsUnit.Pixel); //重置寬 initWidth = initHeight; } //高大於寬的豎圖 else { //物件例項化 pickedImage = new System.Drawing.Bitmap(initWidth, initWidth); pickedG = System.Drawing.Graphics.FromImage(pickedImage); //設定質量 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); //畫圖 pickedG.DrawImage(initImage, toR, fromR, System.Drawing.GraphicsUnit.Pixel); //重置高 initHeight = initWidth; } //將截圖物件賦給原圖 initImage = (System.Drawing.Image)pickedImage.Clone(); //釋放截圖資源 pickedG.Dispose(); pickedImage.Dispose(); } //縮圖物件 System.Drawing.Image resultImage = new System.Drawing.Bitmap(side, side); System.Drawing.Graphics resultG = System.Drawing.Graphics.FromImage(resultImage); //設定質量 resultG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic; resultG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; //用指定背景色清空畫布 resultG.Clear(Color.White); //繪製縮圖 resultG.DrawImage(initImage, new System.Drawing.Rectangle(0, 0, side, side), new System.Drawing.Rectangle(0, 0, initWidth, initHeight), System.Drawing.GraphicsUnit.Pixel); //關鍵質量控制 //獲取系統編碼型別陣列,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); //儲存縮圖 resultImage.Save(fileSaveUrl, ici, ep); //釋放關鍵質量控制所用資源 ep.Dispose(); //釋放縮圖資源 resultG.Dispose(); resultImage.Dispose(); //釋放原始圖片資源 initImage.Dispose(); } } #endregion #region 自定義裁剪並縮放 /// <summary> /// 指定長寬裁剪 /// 按模版比例最大範圍的裁剪圖片並縮放至模版尺寸 /// </summary> /// <remarks>吳劍 2012-08-08</remarks> /// <param name="fromFile">原圖Stream物件</param> /// <param name="fileSaveUrl">儲存路徑</param> /// <param name="maxWidth">最大寬(單位:px)</param> /// <param name="maxHeight">最大高(單位:px)</param> /// <param name="quality">質量(範圍0-100)</param> public static void CutForCustom(System.IO.Stream fromFile, string fileSaveUrl, int maxWidth, int maxHeight, int quality) { //從檔案獲取原始圖片,並使用流中嵌入的顏色管理資訊 System.Drawing.Image initImage = System.Drawing.Image.FromStream(fromFile, true); //原圖寬高均小於模版,不作處理,直接儲存 if (initImage.Width <= maxWidth && initImage.Height <= maxHeight) { initImage.Save(fileSaveUrl, System.Drawing.Imaging.ImageFormat.Jpeg); } else { //模版的寬高比例 double templateRate = (double)maxWidth / maxHeight; //原圖片的寬高比例 double initRate = (double)initImage.Width / initImage.Height; //原圖與模版比例相等,直接縮放 if (templateRate == initRate) { //按模版大小生成最終圖片 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); } //原圖與模版比例不等,裁剪後縮放 else { //裁剪物件 System.Drawing.Image pickedImage = null; System.Drawing.Graphics pickedG = null; //定位 Rectangle fromR = new Rectangle(0, 0, 0, 0);//原圖裁剪定位 Rectangle toR = new Rectangle(0, 0, 0, 0);//目標定位 //寬為標準進行裁剪 if (templateRate > initRate) { //裁剪物件例項化 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); //裁剪目標定位 toR.X = 0; toR.Y = 0; toR.Width = initImage.Width; toR.Height = (int)System.Math.Floor(initImage.Width / templateRate); } //高為標準進行裁剪 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; } //設定質量 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); //按模版大小生成最終圖片 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); //關鍵質量控制 //獲取系統編碼型別陣列,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); //儲存縮圖 templateImage.Save(fileSaveUrl, ici, ep); //templateImage.Save(fileSaveUrl, System.Drawing.Imaging.ImageFormat.Jpeg); //釋放資源 templateG.Dispose(); templateImage.Dispose(); pickedG.Dispose(); pickedImage.Dispose(); } } //釋放資源 initImage.Dispose(); } #endregion #region 等比縮放 /// <summary> /// 圖片等比縮放 /// </summary> /// <remarks>吳劍 2012-08-08</remarks> /// <param name="fromFile">原圖Stream物件</param> /// <param name="savePath">縮圖存放地址</param> /// <param name="targetWidth">指定的最大寬度</param> /// <param name="targetHeight">指定的最大高度</param> /// <param name="watermarkText">水印文字(為""表示不使用水印)</param> /// <param name="watermarkImage">水印圖片路徑(為""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) { //建立目錄 string dir = Path.GetDirectoryName(savePath); if (!Directory.Exists(dir)) Directory.CreateDirectory(dir); //原始圖片(獲取原始圖片建立物件,並使用流中嵌入的顏色管理資訊) System.Drawing.Image initImage = System.Drawing.Image.FromStream(fromFile, true); //原圖寬高均小於模版,不作處理,直接儲存 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("黑體", 10); System.Drawing.Brush brushWater = new SolidBrush(Color.White); gWater.DrawString(watermarkText, fontWater, brushWater, 10, 10); gWater.Dispose(); } } //透明圖片水印 if (watermarkImage != "") { if (File.Exists(watermarkImage)) { //獲取水印圖片 using (System.Drawing.Image wrImage = System.Drawing.Image.FromFile(watermarkImage)) { //水印繪製條件:原始圖片寬高均大於或等於水印圖片 if (initImage.Width >= wrImage.Width && initImage.Height >= wrImage.Height) { Graphics gWater = Graphics.FromImage(initImage); //透明屬性 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(); } } } //儲存 initImage.Save(savePath, System.Drawing.Imaging.ImageFormat.Jpeg); } else { //縮圖寬、高計算 double newWidth = initImage.Width; double newHeight = initImage.Height; //寬大於高或寬等於高(橫圖或正方) if (initImage.Width > initImage.Height || initImage.Width == initImage.Height) { //如果寬大於模版 if (initImage.Width > targetWidth) { //寬按模版,高按比例縮放 newWidth = targetWidth; newHeight = initImage.Height * (targetWidth / initImage.Width); } } //高大於寬(豎圖) else { //如果高大於模版 if (initImage.Height > targetHeight) { //高按模版,寬按比例縮放 newHeight = targetHeight; newWidth = initImage.Width * (targetHeight / initImage.Height); } } //生成新圖 //新建一個bmp圖片 System.Drawing.Image newImage = new System.Drawing.Bitmap((int)newWidth, (int)newHeight); //新建一個畫板 System.Drawing.Graphics newG = System.Drawing.Graphics.FromImage(newImage); //設定質量 newG.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic; newG.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; //置背景色 newG.Clear(Color.White); //畫圖 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("宋體", 10); System.Drawing.Brush brushWater = new SolidBrush(Color.White); gWater.DrawString(watermarkText, fontWater, brushWater, 10, 10); gWater.Dispose(); } } //透明圖片水印 if (watermarkImage != "") { if (File.Exists(watermarkImage)) { //獲取水印圖片 using (System.Drawing.Image wrImage = System.Drawing.Image.FromFile(watermarkImage)) { //水印繪製條件:原始圖片寬高均大於或等於水印圖片 if (newImage.Width >= wrImage.Width && newImage.Height >= wrImage.Height) { Graphics gWater = Graphics.FromImage(newImage); //透明屬性 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(); } } } //儲存縮圖 newImage.Save(savePath, System.Drawing.Imaging.ImageFormat.Jpeg); //釋放資源 newG.Dispose(); newImage.Dispose(); initImage.Dispose(); } } #endregion #region 其它 /// <summary> /// 判斷檔案型別是否為WEB格式圖片 /// (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 }

 

以上就是C#圖片處理的高階應用,希望對大家的學習有所幫助。

 

***********轉載:https://m.jb51.net/article/73353.htm