Create thumbnail image

Question

I want to display thumbnail image in a gridview from file location  How to generate that of  jpeg file  I am using C  language with asp net

User · Accepted Answer

You have to use GetThumbnailImage method in the Image class   https   msdn microsoft com en-us library 8t23aykb 28v vs 110 29 aspx  Here s a rough example that takes an image file and makes a thumbnail image from it  then saves it back to disk   Image image   Image FromFile fileName   Image thumb   image GetThumbnailImage 120  120      gt false  IntPtr Zero   thumb Save Path ChangeExtension fileName   thumb       It is in the System Drawing namespace  in System Drawing dll    Behavior       If the Image contains an embedded thumbnail image  this method   retrieves the embedded thumbnail and scales it to the requested size    If the Image does not contain an embedded thumbnail image  this method   creates a thumbnail image by scaling the main image      Important  the remarks section of the Microsoft link above warns of certain potential problems      The GetThumbnailImage method works well when the requested thumbnail   image has a size of about 120 x 120 pixels  If you request a large   thumbnail image  for example  300 x 300  from an Image that has an   embedded thumbnail  there could be a noticeable loss of quality in the   thumbnail image        It might be better to scale the main image  instead   of scaling the embedded thumbnail  by calling the DrawImage method

User · Answer

This is the code I m using  Also works for  NET Core  gt  2 0 using System Drawing Common NuGet  https   www nuget org packages System Drawing Common  using System  using System Drawing   class Program       static void Main                 const string input    quot C   background1 png quot           const string output    quot C   thumbnail png quot               Load image          Image image   Image FromFile input               Compute thumbnail size          Size thumbnailSize   GetThumbnailSize image               Get thumbnail          Image thumbnail   image GetThumbnailImage thumbnailSize Width              thumbnailSize Height  null  IntPtr Zero               Save thumbnail          thumbnail Save output              static Size GetThumbnailSize Image original                   Maximum size of any dimension          const int maxPixels   40              Width and height          int originalWidth   original Width          int originalHeight   original Height              Return original size if image is smaller than maxPixels         if  originalWidth  lt   maxPixels    originalHeight  lt   maxPixels                        return new Size originalWidth  originalHeight                            Compute best factor to scale entire image based on larger dimension          double factor          if  originalWidth  gt  originalHeight                        factor    double maxPixels   originalWidth                    else                       factor    double maxPixels   originalHeight                        Return thumbnail size          return new Size  int  originalWidth   factor    int  originalHeight   factor             Source  https   www dotnetperls com getthumbnailimage

User · Answer

Here is a complete example of how to create a smaller image  thumbnail   This snippet resizes the Image  rotates it when needed  if a phone was held vertically  and pads the image if you want to create square thumbs  This snippet creates a JPEG  but it can easily be modified for other file types  Even if the image would be smaller than the max allowed size the image will still be compressed and it s resolution altered to create images of the same dpi and compression level   using System  using System Drawing  using System Drawing Drawing2D  using System Drawing Imaging  using System IO     set the resolution  72 is usually good enough for displaying images on monitors float imageResolution   72     set the compression level  higher compression   better quality   bigger images long compressionLevel   80L    public Image resizeImage Image image  int maxWidth  int maxHeight  bool padImage        int newWidth      int newHeight         first we check if the image needs rotating  eg phone held vertical when taking a picture for example      foreach  var prop in image PropertyItems                if  prop Id    0x0112                        int orientationValue   image GetPropertyItem prop Id  Value 0               RotateFlipType rotateFlipType   getRotateFlipType orientationValue               image RotateFlip rotateFlipType               break                         apply the padding to make a square image     if  padImage    true                image   applyPaddingToImage image  Color Red                check if the with or height of the image exceeds the maximum specified  if so calculate the new dimensions     if  image Width  gt  maxWidth    image Height  gt  maxHeight                double ratioX    double maxWidth   image Width          double ratioY    double maxHeight   image Height          double ratio   Math Min ratioX  ratioY            newWidth    int  image Width   ratio           newHeight    int  image Height   ratio             else               newWidth   image Width          newHeight   image Height               start the resize with a new image     Bitmap newImage   new Bitmap newWidth  newHeight          set the new resolution     newImage SetResolution imageResolution  imageResolution          start the resizing     using  var graphics   Graphics FromImage newImage                   set some encoding specs         graphics CompositingMode   CompositingMode SourceCopy          graphics CompositingQuality   CompositingQuality HighQuality          graphics SmoothingMode   SmoothingMode HighQuality          graphics InterpolationMode   InterpolationMode HighQualityBicubic          graphics PixelOffsetMode   PixelOffsetMode HighQuality           graphics DrawImage image  0  0  newWidth  newHeight                save the image to a memorystream to apply the compression level     using  MemoryStream ms   new MemoryStream                  EncoderParameters encoderParameters   new EncoderParameters 1           encoderParameters Param 0    new EncoderParameter Encoder Quality  compressionLevel            newImage Save ms  getEncoderInfo  image jpeg    encoderParameters              save the image as byte array here if you want the return type to be a Byte Array instead of Image           byte   imageAsByteArray   ms ToArray                 return the image     return newImage            image padding public Image applyPaddingToImage Image image  Color backColor          get the maximum size of the image dimensions     int maxSize   Math Max image Height  image Width       Size squareSize   new Size maxSize  maxSize          create a new square image     Bitmap squareImage   new Bitmap squareSize Width  squareSize Height        using  Graphics graphics   Graphics FromImage squareImage                   fill the new square with a color         graphics FillRectangle new SolidBrush backColor   0  0  squareSize Width  squareSize Height              put the original image on top of the new square         graphics DrawImage image   squareSize Width   2  -  image Width   2    squareSize Height   2  -  image Height   2   image Width  image Height                return the image     return squareImage            get encoder info private ImageCodecInfo getEncoderInfo string mimeType        ImageCodecInfo   encoders   ImageCodecInfo GetImageEncoders         for  int j   0  j  lt  encoders Length    j                if  encoders j  MimeType ToLower      mimeType ToLower                          return encoders j                        return null            determine image rotation private RotateFlipType getRotateFlipType int rotateValue        RotateFlipType flipType   RotateFlipType RotateNoneFlipNone       switch  rotateValue                case 1              flipType   RotateFlipType RotateNoneFlipNone              break          case 2              flipType   RotateFlipType RotateNoneFlipX              break          case 3              flipType   RotateFlipType Rotate180FlipNone              break          case 4              flipType   RotateFlipType Rotate180FlipX              break          case 5              flipType   RotateFlipType Rotate90FlipX              break          case 6              flipType   RotateFlipType Rotate90FlipNone              break          case 7              flipType   RotateFlipType Rotate270FlipX              break          case 8              flipType   RotateFlipType Rotate270FlipNone              break          default              flipType   RotateFlipType RotateNoneFlipNone              break             return flipType           convert image to base64 public string convertImageToBase64 Image image        using  MemoryStream ms   new MemoryStream                    convert the image to byte array         image Save ms  ImageFormat Jpeg           byte   bin   ms ToArray               convert byte array to base64 string         return Convert ToBase64String bin             For the asp net users a little example of how to upload a file  resize it and display the result on the page        the button click method protected void Button1 Click object sender  EventArgs e          check if there is an actual file being uploaded     if  FileUpload1 HasFile    false                return             using  Bitmap bitmap   new Bitmap FileUpload1 PostedFile InputStream                 try                         start the resize             Image image   resizeImage bitmap  256  256  true                  to visualize the result  display as base64 image             Label1 Text     lt img src   data image jpg base64     convertImageToBase64 image        gt                   save your image to file sytem  database etc here                   catch  Exception ex                        Label1 Text    Oops  There was an error when resizing the Image  lt br gt Error      ex Message

User · Answer

Here is an example to convert high res image into thumbnail size-  protected void Button1 Click object sender  EventArgs e          ----------        Getting the Image File     System Drawing Image img   System Drawing Image FromFile Server MapPath    profile Avatar jpg            ----------        Getting Size of Original Image     double imgHeight   img Size Height      double imgWidth   img Size Width         ----------        Getting Decreased Size     double x   imgWidth   200      int newWidth   Convert ToInt32 imgWidth   x       int newHeight   Convert ToInt32 imgHeight   x          ----------        Creating Small Image     System Drawing Image GetThumbnailImageAbort myCallback   new System Drawing Image GetThumbnailImageAbort ThumbnailCallback       System Drawing Image myThumbnail   img GetThumbnailImage newWidth  newHeight  myCallback  IntPtr Zero          ----------        Saving Image     myThumbnail Save Server MapPath    profile NewImage jpg       public bool ThumbnailCallback         return false      Source- http   iknowledgeboy blogspot in 2014 03 c-creating-thumbnail-of-large-image-by html

User · Answer

The following code will write an image in proportional to the response  you can modify the code for your purpose   public void WriteImage string path  int width  int height        Bitmap srcBmp   new Bitmap path       float ratio   srcBmp Width   srcBmp Height      SizeF newSize   new SizeF width  height   ratio       Bitmap target   new Bitmap  int  newSize Width  int  newSize Height       HttpContext Response Clear        HttpContext Response ContentType    image jpeg       using  Graphics graphics   Graphics FromImage target                 graphics CompositingQuality   CompositingQuality HighSpeed          graphics InterpolationMode   InterpolationMode HighQualityBicubic          graphics CompositingMode   CompositingMode SourceCopy          graphics DrawImage srcBmp  0  0  newSize Width  newSize Height           using  MemoryStream memoryStream   new MemoryStream                           target Save memoryStream  ImageFormat Jpeg               memoryStream WriteTo HttpContext Response OutputStream                       Response End

User · Answer

Here is a version based on the accepted answer   It fixes two problems     Improper disposing of the images  Maintaining the aspect ratio of the image   I found this tool to be fast and effective for both JPG and PNG files  private static FileInfo CreateThumbnailImage string imageFileName  string thumbnailFileName        const int thumbnailSize   150      using  var image   Image FromFile imageFileName                 var imageHeight   image Height          var imageWidth   image Width          if  imageHeight  gt  imageWidth                        imageWidth    int     float  imageWidth    float  imageHeight    thumbnailSize               imageHeight   thumbnailSize                    else                       imageHeight    int     float  imageHeight    float  imageWidth    thumbnailSize               imageWidth   thumbnailSize                     using  var thumb   image GetThumbnailImage imageWidth  imageHeight       gt  false  IntPtr Zero                 Save off the new thumbnail             thumb Save thumbnailFileName              return new FileInfo thumbnailFileName

[c#] Create thumbnail image

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