今天小编给大家分享一下C#怎么实现无损压缩图片的相关知识点，内容详细，逻辑清晰，相信大部分人都还太了解这方面的知识，所以分享这篇文章给大家参考一下，希望大家阅读完这篇文章后有所收获，下面我们一起来了解一下吧。
一般在web应用中，对客户端提交上来的图片肯定需要进行压缩的。尤其是比较大的图片，如果不经过压缩会导致页面变的很大，打开速度比较慢，影响用户体验，所以一般会将图片进行压缩。
代码实现：
using System;using System.Collections.Generic;using System.ComponentModel;using System.Data;using System.Drawing;using System.Drawing.Imaging;using System.IO;using System.Linq;using System.Text;using System.Threading.Tasks;using System.Windows.Forms;namespace ImageCompress{ public partial class Form1 : Form { public Form1() { InitializeComponent(); } /// <summary> /// 无损压缩图片 /// </summary> /// <param name="sFile">原图片地址(包含图片名称)</param> /// <param name="dFile">压缩后保存图片地址(包含图片名称)</param> /// <param name="flag">压缩质量（数字越小压缩率越高）1-100</param> /// <param name="size">压缩后图片的最大大小</param> /// <param name="sfsc">是否是第一次调用</param> /// <returns></returns> public static bool CompressImage(string sFile, string dFile, int flag = 90, int size = 300, bool sfsc = true) { //如果是第一次调用，原始图像的大小小于要压缩的大小，则直接复制文件，并且返回true FileInfo firstFileInfo = new FileInfo(sFile); if (sfsc == true && firstFileInfo.Length < size * 1024) { firstFileInfo.CopyTo(dFile); return true; } Image iSource = Image.FromFile(sFile); ImageFormat tFormat = iSource.RawFormat; int dHeight = iSource.Height / 2; int dWidth = iSource.Width / 2; 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 = System.Drawing.Drawing2D.CompositingQuality.HighQuality; g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality; g.InterpolationMode = System.Drawing.Drawing2D.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 FileInfo fi = new FileInfo(dFile); if (fi.Length > 1024 * size) { flag = flag - 10; CompressImage(sFile, dFile, flag, size, false); } } else { ob.Save(dFile, tFormat); } return true; } catch { return false; } finally { iSource.Dispose(); ob.Dispose(); } } private void button1_Click(object sender, EventArgs e) { string sfile = @"C:\Users\Mingliang_wang\Pictures\Screenshots\s_test.jpg"; string dfile = @"C:\Users\Mingliang_wang\Pictures\Screenshots\d_test.jpg"; CompressImage(sfile,dfile); } }}以上就是“C#怎么实现无损压缩图片”这篇文章的所有内容，感谢各位的阅读！相信大家阅读完这篇文章都有很大的收获，小编每天都会为大家更新不同的知识，如果还想学习更多的知识，请关注编程网行业资讯频道。
