C# 操作图片的部分方法,包含 图片加载、压缩、base64等

public static class ImageHelper
    {
 
        #region 图片
        public static EncoderParameters GetEncoderParas(long picquality)
        {
            EncoderParameters eps = new EncoderParameters(1);
            Encoder ec = Encoder.Quality;
            EncoderParameter ep = new EncoderParameter(ec, picquality);
            eps.Param[0] = ep;
 
            return eps;
        }
 
        public static ImageCodecInfo GetJpegCodecInfo()
        {
            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;
                }
            }
 
            return jpegICIinfo;
        }
 
        public static System.Drawing.Image GetImage(string path)
        {
            FileStream fs = new FileStream(path, FileMode.Open);
            Image result = Image.FromStream(fs);
 
            fs.Close();
 
            return result;
        }
 
        public static Bitmap GetImageFromBase64(string base64string)
        {
            byte[] b = Convert.FromBase64String(base64string);
            MemoryStream ms = new MemoryStream(b);
            Bitmap bitmap = new Bitmap(ms);
            return bitmap;
        }
 
        public static string GetBase64FromImage(string imagefile)
        {
            string strbaser64 = "";
            try
            {
                Bitmap bmp = new Bitmap(imagefile);
                MemoryStream ms = new MemoryStream();
                bmp.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
                byte[] arr = new byte[ms.Length];
                ms.Position = 0;
                ms.Read(arr, 0, (int)ms.Length);
                ms.Close();
                strbaser64 = Convert.ToBase64String(arr);
            }
            catch (Exception)
            {
                return "";
            }
            return strbaser64;
        }
 
        /// <summary>
        /// 按照比例缩小图片
        /// </summary>
        /// <param name="srcImage">要缩小的图片</param>
        /// <param name="percent">缩小比例</param>
        /// <returns>缩小后的结果</returns>
        public static Bitmap PercentImage(Image srcImage, double percent)
        {
            // 缩小后的高度
            int newH = int.Parse(Math.Round(srcImage.Height * percent).ToString());
            // 缩小后的宽度
            int newW = int.Parse(Math.Round(srcImage.Width * percent).ToString());
            try
            {
                // 要保存到的图片
                Bitmap b = new Bitmap(newW, newH);
                Graphics g = Graphics.FromImage(b);
                // 插值算法的质量
                g.InterpolationMode = InterpolationMode.Default;
                g.DrawImage(srcImage, new Rectangle(0, 0, newW, newH), new Rectangle(0, 0, srcImage.Width, srcImage.Height), GraphicsUnit.Pixel);
                g.Dispose();
                return b;
            }
            catch (Exception)
            {
                return null;
            }
        }
 
        /// <summary>
        /// 按照指定大小缩放图片
        /// </summary>
        /// <param name="srcImage"></param>
        /// <param name="iWidth"></param>
        /// <param name="iHeight"></param>
        /// <returns></returns>
        public static Bitmap SizeImage(Image srcImage, int iWidth, int iHeight)
        {
            try
            {
                // 要保存到的图片
                Bitmap b = new Bitmap(iWidth, iHeight);
                Graphics g = Graphics.FromImage(b);
                // 插值算法的质量
                g.InterpolationMode = InterpolationMode.HighQualityBicubic;
                g.DrawImage(srcImage, new Rectangle(0, 0, iWidth, iHeight), new Rectangle(0, 0, srcImage.Width, srcImage.Height), GraphicsUnit.Pixel);
                g.Dispose();
                return b;
            }
            catch (Exception ex)
            {
                return null;
            }
        }
 
        /// <summary>
        /// jpeg图片压缩
        /// </summary>
        /// <param name="sFile"></param>
        /// <param name="outPath"></param>
        /// <param name="flag"></param>
        /// <returns></returns>
        public static bool GetPicThumbnail(string sFile, string outPath, int flag)
        {
            if (File.Exists(outPath)) File.Delete(outPath);
 
            System.Drawing.Image iSource = System.Drawing.Image.FromFile(sFile);
            ImageFormat tFormat = iSource.RawFormat;
            //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)
                {
                    iSource.Save(outPath, jpegICIinfo, ep);//dFile是压缩后的新路径
                }
                else
                {
                    iSource.Save(outPath, tFormat);
                }
                return true;
            }
            catch (Exception ex)
            {
                return false;
            }
            finally
            {
                iSource.Dispose();
            }
        }
        #endregion
    }