c# 无损高质量压缩图片代码

r囧r小猫 2022-11-21 04:25 179阅读 0赞

最近，项目上涉及到了图像压缩，发现原有的图像压缩功能，虽然保证了图像的大小300K以内，但是压缩后的图像看的不在清晰，并且，限定了图片的Height或者是Width。

在CSDN上看到了一个压缩算法：[http://blog.csdn.net/qq\_16542775/article/details/51792149][http_blog.csdn.net_qq_16542775_article_details_51792149]

进过测试这个算法，发现，将原始图像的大小进行对半处理，然后迭代跳转压缩质量参数，可以得到不错的效果。

修改后的算法如下：

/// <summary>
    /// 无损压缩图片
    /// </summary>
    /// <param name="sFile">原图片地址</param>
    /// <param name="dFile">压缩后保存图片地址</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();
        }
    }

效果图如下：

第一张的大小是2.82M，尺寸是3680\*4640。[![1500593c857c34c7e49cc77a2cab6da7.png][]][1500593c857c34c7e49cc77a2cab6da7.png 1]

第二张的大小是274KB，尺寸是1740\*2320，清晰度方面还是不错的。

[![77a37eb52a8faba299d65c08bb8aa928.png][]][77a37eb52a8faba299d65c08bb8aa928.png 1]

作者：衆尋

出处：[https://www.cnblogs.com/ZXdeveloper/p/6841878.html][https_www.cnblogs.com_ZXdeveloper_p_6841878.html]

版权：本文采用「[署名 4.0 国际][4.0]」知识共享许可协议进行许可。

[http_blog.csdn.net_qq_16542775_article_details_51792149]: http://blog.csdn.net/qq_16542775/article/details/51792149
[1500593c857c34c7e49cc77a2cab6da7.png]: /images/20221120/92d9c3f488954db9862b539609a9626a.png
[1500593c857c34c7e49cc77a2cab6da7.png 1]: https://images2015.cnblogs.com/blog/609679/201705/609679-20170511172526254-243229213.jpg
[77a37eb52a8faba299d65c08bb8aa928.png]: /images/20221120/88f88775f83242288a5accbe1ea293f3.png
[77a37eb52a8faba299d65c08bb8aa928.png 1]: https://images2015.cnblogs.com/blog/609679/201705/609679-20170511172556222-519557790.jpg
[https_www.cnblogs.com_ZXdeveloper_p_6841878.html]: https://www.cnblogs.com/ZXdeveloper/p/6841878.html
[4.0]: https://creativecommons.org/licenses/by/4.0