使用C#进行图片转换格式,缩放,自动旋转,保留exif（转载）

这几天心血来潮做了一个批量图片缩放,转换格式,并且可以根据exif的信息旋转图片,校正exif信息后保存的小程序.根据配置文件 指定需要的功能.

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211

using System; using System.IO; using System.Drawing.Imaging; using System.Drawing; using System.Drawing.Drawing2D; using System.Runtime.InteropServices; using System.Text;   namespace PhotoUtil {      class Program      {          [DllImport( "kernel32" )]          private static extern long GetPrivateProfileString( string section, string key,              string def, StringBuilder retVal, int size, string filePath);          private const String configFile = "Config.ini" ;            public static void Main( string [] args)          {              DirectoryInfo workingDir = new DirectoryInfo(ReadConfig( "General" , "WorkingDir" ,Environment.CurrentDirectory));              if (!workingDir.Exists)              {                  workingDir = new DirectoryInfo(Environment.CurrentDirectory);              }              int quality= int .Parse(ReadConfig( "General" , "Quality" , "85" ));              bool needResize = Boolean.Parse(ReadConfig( "ResizeImage" , "Enable" , "false" ));              int newWidth = int .Parse(ReadConfig( "ResizeImage" , "NewWidth" , "800" ));              int newHeight = int .Parse(ReadConfig( "ResizeImage" , "NewHeight" , "600" ));              bool padding = Boolean.Parse(ReadConfig( "ResizeImage" , "Padding" , "false" ));              bool needRotate = Boolean.Parse(ReadConfig( "RotateImage" , "Enable" , "true" ));              FileInfo[] files = workingDir.GetFiles();              DirectoryInfo output = workingDir.CreateSubdirectory(DateTime.Now.ToString( "yyyyMMdd" ) + "转换\r              foreach (FileInfo i in files)              {                  String type = i.Extension.ToLower();                  if (type.Contains( "jpg" ) || type.Contains( "jpeg" ) || (type.Contains( "png" )) || type.Contains( "tif" ) || type.Contains( "bmp" ))                  {                      Image img = Image.FromFile(i.FullName);                      if (needResize)                      {                          Console.WriteLine( "Resizing " + i.FullName);                          ResizeImage( ref img, newWidth, newHeight, padding);                      }                      if (needRotate)                      {                          Console.WriteLine( "Rotating " + i.FullName);                          RotateImage(img);                      }                      SaveAs(img, output.FullName+ "\\\\" +i.Name, quality);                  }              }              Console.ReadLine();          }            private static void SaveAs(Image img, string dest, long quality)          {              if (quality > 100 || quality < 1)              {                  quality = 85;              }              EncoderParameters para = new EncoderParameters();              para.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, quality);              String extension = new FileInfo(dest).Extension;              ImageCodecInfo info = GetImageCodecInfoByExtension(extension);              if (info != null )              {                  img.Save(dest, info, para);              }              else              {                  throw new Exception( "Unrecognized  format \\" " + extension + " \\"!\r              }          }            private static void ResizeImage( ref Image image, int expectDestWidth, int expectDestHeight, bool padding)          {              PropertyItem[] exif = image.PropertyItems;              int targetWidth = 0;              int targetHeight = 0;              double srcHWRate = ( double )image.Width / ( double )image.Height;              double expectHWRate = ( double )expectDestWidth / ( double )expectDestHeight;              if (srcHWRate > expectHWRate)              {                  targetWidth = expectDestWidth;                  targetHeight = System.Convert.ToInt32(Math.Round(expectDestWidth / srcHWRate, 0));              }              else              {                  targetHeight = expectDestHeight;                  targetWidth = System.Convert.ToInt32(Math.Round(expectDestHeight * srcHWRate, 0));              }                Image bitmap = null ;              if (!padding)              {                  bitmap = new Bitmap(targetWidth, targetHeight);              }              else              {                  bitmap = new Bitmap(expectDestWidth, expectDestHeight);              }              Graphics g = Graphics.FromImage(bitmap);              g.CompositingQuality = CompositingQuality.HighQuality;              g.InterpolationMode = InterpolationMode.HighQualityBicubic;              g.SmoothingMode = SmoothingMode.HighQuality;              g.DrawImage(image, new Rectangle(0, 0, bitmap.Width, bitmap.Height), new Rectangle(0, 0, image.Width, image.Height), GraphicsUnit.Pixel);              foreach (PropertyItem i in exif)              {                  if (i.Id == 40962)                  {                      i.Value = BitConverter.GetBytes(targetWidth);                  }                  else if (i.Id == 40963)                  {                      i.Value = BitConverter.GetBytes(targetHeight);                  }                  bitmap.SetPropertyItem(i);              }              g.Dispose();              image.Dispose();              image = bitmap;          }            private static string ReadConfig(String Section, String Key, String defaultValue)          {              if (File.Exists(configFile))              {                  StringBuilder temp = new StringBuilder(1024);                  GetPrivateProfileString(Section, Key, String.Empty, temp, 1024, new FileInfo(configFile).FullName);                  if (!String.IsNullOrEmpty(temp.ToString()))                  {                      return temp.ToString();                  }                  else                  {                      return defaultValue;                  }              }              else              {                  return defaultValue;              }          }            public static void RotateImage(Image img)          {              PropertyItem[] exif = img.PropertyItems;              byte orientation = 0;              foreach (PropertyItem i in exif)              {                  if (i.Id == 274)                  {                      orientation = i.Value[0];                      i.Value[0] = 1;                      img.SetPropertyItem(i);                  }              }                switch (orientation)              {                  case 2:                      img.RotateFlip(RotateFlipType.RotateNoneFlipX);                      break ;                  case 3:                      img.RotateFlip(RotateFlipType.Rotate180FlipNone);                      break ;                  case 4:                      img.RotateFlip(RotateFlipType.RotateNoneFlipY);                      break ;                  case 5:                      img.RotateFlip(RotateFlipType.Rotate90FlipX);                      break ;                  case 6:                      img.RotateFlip(RotateFlipType.Rotate90FlipNone);                      break ;                  case 7:                      img.RotateFlip(RotateFlipType.Rotate270FlipX);                      break ;                  case 8:                      img.RotateFlip(RotateFlipType.Rotate270FlipNone);                      break ;                  default :                      break ;              }              foreach (PropertyItem i in exif)              {                  if (i.Id == 40962)                  {                      i.Value = BitConverter.GetBytes(img.Width);                  }                  else if (i.Id == 40963)                  {                      i.Value = BitConverter.GetBytes(img.Height);                  }              }          }            private static ImageCodecInfo GetImageCodecInfoByExtension(String extension)          {              ImageCodecInfo[] list = ImageCodecInfo.GetImageEncoders();              foreach (ImageCodecInfo i in list)              {                  if (i.FilenameExtension.ToLower().Contains(extension.ToLower()))                  {                      return i;                  }              }              return null ;          }      } }

配置文件名称:Config.ini,放在和程序同目录下,格式如下:
[General]
#工作目录
WorkingDir=.
#输出质量，1-100范围内的整数
Quality=80

[ResizeImage]
#是否启用
Enable=true
#新的宽值和高值
NewWidth=1024
NewHeight=768
#是否对超出原来比例的部分进行填充
Padding=false

#是否使用Exif中的旋转信息对图片进行旋转
[RotateImage]
Enable=true

1.保留exif信息的技巧是获取原始的Image.PropertyItems,对新图片添加即可.
2.关于Exif Orientation标志的定义 http://sylvana.net/jpegcrop/exif_orientation.html
3.变更jpeg输出质量的方法:
EncoderParameters para = new EncoderParameters();
para.Param[0] = new EncoderParameter(System.Drawing.Imaging.Encoder.Quality, quality);
//这里的quality是从1-100的long值,一开始想当然的以为1-100的值就用了byte,结果出错了.
最后调用Image.Save(String, ImageCodecInfo, EncoderParameters)来进行输出.
4.进行缩放/旋转后需要调整原始的exif信息,id查文档可知.列出一些
id=40962,width
id=40963,height
id=274,orientation type
对PropertyItem信息设置完了别忘了Image.SetPropertyItem(PropertyItem)添加到image中,我出一个很 傻的bug,就是在修改了orientation type=1之后没有SetPropertyItem,于是导致图片实际被旋转至正确角度了,但是用ACDSee打开后可以看到exif的旋转信息依旧是 原来的值.