How to resize an Image C

Question

As Size  Width and Height are Get   properties of System Drawing Image  How can I resize an Image object at run-time in C    Right now  I am just creating a new Image using      objImage is the original Image Bitmap objBitmap   new Bitmap objImage  new Size 227  171

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You can use the Accord NET framework for this  It provides a few different methods of resizing    Bicubic Bilinear Nearest Neighbour

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This code is same as posted from one of above answers   but will convert transparent pixel to white instead of black     Thanks        public Image resizeImage int newWidth  int newHeight  string stPhotoPath                Image imgPhoto   Image FromFile stPhotoPath            int sourceWidth   imgPhoto Width          int sourceHeight   imgPhoto Height             Consider vertical pics         if  sourceWidth  lt  sourceHeight                        int buff   newWidth               newWidth   newHeight              newHeight   buff                     int sourceX   0  sourceY   0  destX   0  destY   0          float nPercent   0  nPercentW   0  nPercentH   0           nPercentW     float newWidth    float sourceWidth           nPercentH     float newHeight    float sourceHeight           if  nPercentH  lt  nPercentW                        nPercent   nPercentH              destX   System Convert ToInt16  newWidth -                        sourceWidth   nPercent     2                     else                       nPercent   nPercentW              destY   System Convert ToInt16  newHeight -                        sourceHeight   nPercent     2                      int destWidth    int  sourceWidth   nPercent           int destHeight    int  sourceHeight   nPercent             Bitmap bmPhoto   new Bitmap newWidth  newHeight                        PixelFormat Format24bppRgb            bmPhoto SetResolution imgPhoto HorizontalResolution                       imgPhoto VerticalResolution            Graphics grPhoto   Graphics FromImage bmPhoto           grPhoto Clear Color White           grPhoto InterpolationMode               System Drawing Drawing2D InterpolationMode HighQualityBicubic           grPhoto DrawImage imgPhoto              new Rectangle destX  destY  destWidth  destHeight               new Rectangle sourceX  sourceY  sourceWidth  sourceHeight               GraphicsUnit Pixel            grPhoto Dispose            imgPhoto Dispose             return bmPhoto

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Resize and save an image to fit under width and height like a canvas keeping image proportional  using System  using System Drawing  using System Drawing Drawing2D  using System Drawing Imaging  using System IO   namespace Infra Files       public static class GenerateThumb                    lt summary gt              Resize and save an image to fit under width and height like a canvas keeping things proportional              lt  summary gt               lt param name  originalImagePath  gt  lt  param gt               lt param name  thumbImagePath  gt  lt  param gt               lt param name  newWidth  gt  lt  param gt               lt param name  newHeight  gt  lt  param gt          public static void GenerateThumbImage string originalImagePath  string thumbImagePath  int newWidth  int newHeight                        Bitmap srcBmp   new Bitmap originalImagePath               float ratio   1              float minSize   Math Min newHeight  newHeight                if  srcBmp Width  gt  srcBmp Height                                ratio   minSize    float srcBmp Width                            else                               ratio   minSize    float srcBmp Height                             SizeF newSize   new SizeF srcBmp Width   ratio  srcBmp Height   ratio               Bitmap target   new Bitmap  int newSize Width   int newSize Height                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 thumbImagePath

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public static Image resizeImage Image image  int new height  int new width        Bitmap new image   new Bitmap new width  new height       Graphics g   Graphics FromImage  Image new image        g InterpolationMode   InterpolationMode High      g DrawImage image  0  0  new width  new height       return new image

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Not sure what is so difficult about this  do what you were doing  use the overloaded Bitmap constructor to create a re-sized image  the only thing you were missing was a cast back to the Image data type  public static Image resizeImage Image imgToResize  Size size        return  Image  new Bitmap imgToResize  size       yourImage   resizeImage yourImage  new Size 50 50

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public string CreateThumbnail int maxWidth  int maxHeight  string path         var image   System Drawing Image FromFile path       var ratioX    double maxWidth   image Width      var ratioY    double maxHeight   image Height      var ratio   Math Min ratioX  ratioY       var newWidth    int  image Width   ratio       var newHeight    int  image Height   ratio       var newImage   new Bitmap newWidth  newHeight       Graphics thumbGraph   Graphics FromImage newImage        thumbGraph CompositingQuality   CompositingQuality HighQuality      thumbGraph SmoothingMode   SmoothingMode HighQuality        thumbGraph InterpolationMode   InterpolationMode HighQualityBicubic       thumbGraph DrawImage image  0  0  newWidth  newHeight       image Dispose         string fileRelativePath    newsizeimages     maxWidth   Path GetFileName path       newImage Save Server MapPath fileRelativePath   newImage RawFormat       return fileRelativePath      Click here http   bhupendrasinghsaini blogspot in 2014 07 resize-image-in-c html

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in this question  you ll have some answers  including mine   public Image resizeImage int newWidth  int newHeight  string stPhotoPath          Image imgPhoto   Image FromFile stPhotoPath          int sourceWidth   imgPhoto Width       int sourceHeight   imgPhoto Height          Consider vertical pics     if  sourceWidth  lt  sourceHeight                int buff   newWidth           newWidth   newHeight          newHeight   buff             int sourceX   0  sourceY   0  destX   0  destY   0      float nPercent   0  nPercentW   0  nPercentH   0       nPercentW     float newWidth    float sourceWidth       nPercentH     float newHeight    float sourceHeight       if  nPercentH  lt  nPercentW                nPercent   nPercentH          destX   System Convert ToInt16  newWidth -                    sourceWidth   nPercent     2             else               nPercent   nPercentW          destY   System Convert ToInt16  newHeight -                    sourceHeight   nPercent     2              int destWidth    int  sourceWidth   nPercent       int destHeight    int  sourceHeight   nPercent         Bitmap bmPhoto   new Bitmap newWidth  newHeight                    PixelFormat Format24bppRgb        bmPhoto SetResolution imgPhoto HorizontalResolution                   imgPhoto VerticalResolution        Graphics grPhoto   Graphics FromImage bmPhoto       grPhoto Clear Color Black       grPhoto InterpolationMode           System Drawing Drawing2D InterpolationMode HighQualityBicubic       grPhoto DrawImage imgPhoto          new Rectangle destX  destY  destWidth  destHeight           new Rectangle sourceX  sourceY  sourceWidth  sourceHeight           GraphicsUnit Pixel        grPhoto Dispose        imgPhoto Dispose        return bmPhoto

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This will -   Resize width AND height without the need for a loop Doesn t exceed the images original dimensions                   private void ResizeImage Image img  double maxWidth  double maxHeight        double resizeWidth   img Source Width      double resizeHeight   img Source Height       double aspect   resizeWidth   resizeHeight       if  resizeWidth  gt  maxWidth                resizeWidth   maxWidth          resizeHeight   resizeWidth   aspect            if  resizeHeight  gt  maxHeight                aspect   resizeWidth   resizeHeight          resizeHeight   maxHeight          resizeWidth   resizeHeight   aspect             img Width   resizeWidth      img Height   resizeHeight

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Why not use the System Drawing Image GetThumbnailImage method   public Image GetThumbnailImage      int thumbWidth       int thumbHeight       Image GetThumbnailImageAbort callback       IntPtr callbackData    Example   Image originalImage   System Drawing Image FromStream inputStream  true  true   Image resizedImage   originalImage GetThumbnailImage newWidth   newWidth   originalImage Height    originalWidth  null  IntPtr Zero   resizedImage Save imagePath  ImageFormat Png     Source  http   msdn microsoft com en-us library system drawing image getthumbnailimage aspx

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Note  this will not work with ASP Net Core because WebImage depends on System Web  but on previous versions of ASP Net I used this snippet many times and was useful   String ThumbfullPath   Path GetFileNameWithoutExtension file FileName     80x80 jpg   var ThumbfullPath2   Path Combine ThumbfullPath  fileThumb   using  MemoryStream stream   new MemoryStream System IO File ReadAllBytes fullPath            var thumbnail   new WebImage stream  Resize 80  80         thumbnail Save ThumbfullPath2   jpg

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Use below function with below example for changing image size       Example    System Net Mime MediaTypeNames Image newImage   System Net Mime MediaTypeNames Image FromFile  SampImag jpg    System Net Mime MediaTypeNames Image temImag   FormatImage newImage  100  100      image size modification unction    public static System Net Mime MediaTypeNames Image FormatImage System Net Mime MediaTypeNames Image img  int outputWidth  int outputHeight         Bitmap outputImage   null      Graphics graphics   null      try                outputImage   new Bitmap outputWidth  outputHeight  System Drawing Imaging PixelFormat Format16bppRgb555            graphics   Graphics FromImage outputImage            graphics DrawImage img  new Rectangle 0  0  outputWidth  outputHeight            new Rectangle 0  0  img Width  img Height   GraphicsUnit Pixel             return outputImage              catch  Exception ex                    return img

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I use ImageProcessorCore  mostly because it works  Net Core   And it have more option such as converting types  cropping images and more     http   imageprocessor org imageprocessor

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In the application I made it was necessary to create a function with multiple options  It s quite large  but it resizes the image  can keep the aspect ratio and can cut of the edges to return only the center of the image        lt summary gt          Resize image with a directory as source          lt  summary gt           lt param name  OriginalFileLocation  gt Image location lt  param gt           lt param name  heigth  gt new height lt  param gt           lt param name  width  gt new width lt  param gt           lt param name  keepAspectRatio  gt keep the aspect ratio lt  param gt           lt param name  getCenter  gt return the center bit of the image lt  param gt           lt returns gt image with new dimentions lt  returns gt      public Image resizeImageFromFile String OriginalFileLocation  int heigth  int width  Boolean keepAspectRatio  Boolean getCenter                int newheigth   heigth          System Drawing Image FullsizeImage   System Drawing Image FromFile OriginalFileLocation               Prevent using images internal thumbnail         FullsizeImage RotateFlip System Drawing RotateFlipType Rotate180FlipNone           FullsizeImage RotateFlip System Drawing RotateFlipType Rotate180FlipNone            if  keepAspectRatio    getCenter                        int bmpY   0              double resize    double FullsizeImage Width    double width   get the resize vector             if  getCenter                                bmpY    int   FullsizeImage Height -  heigth   resize     2     gives the Y value of the part that will be cut off  to show only the part in the center                 Rectangle section   new Rectangle new Point 0  bmpY   new Size FullsizeImage Width   int  heigth   resize       create the section to cut of the original image                   System Console WriteLine  the section that will be cut off      section Size ToString       the Y value is minimized by      bmpY                   Bitmap orImg   new Bitmap  Bitmap FullsizeImage    for the correct effect convert image to bitmap                  FullsizeImage Dispose     clear the original image                 using  Bitmap tempImg   new Bitmap section Width  section Height                                         Graphics cutImg   Graphics FromImage tempImg                  set the file to save the new image to                      cutImg DrawImage orImg  0  0  section  GraphicsUnit Pixel     cut the image and save it to tempImg                     FullsizeImage   tempImg   save the tempImg as FullsizeImage for resizing later                     orImg Dispose                        cutImg Dispose                        return FullsizeImage GetThumbnailImage width  heigth  null  IntPtr Zero                                               else newheigth    int  FullsizeImage Height   resize      set the new heigth of the current image            return the image resized to the given heigth and width         return FullsizeImage GetThumbnailImage width  newheigth  null  IntPtr Zero           To make it easier to acces the function it s possible to add some overloaded functions        lt summary gt          Resize image with a directory as source          lt  summary gt           lt param name  OriginalFileLocation  gt Image location lt  param gt           lt param name  heigth  gt new height lt  param gt           lt param name  width  gt new width lt  param gt           lt returns gt image with new dimentions lt  returns gt      public Image resizeImageFromFile String OriginalFileLocation  int heigth  int width                return resizeImageFromFile OriginalFileLocation  heigth  width  false  false                   lt summary gt          Resize image with a directory as source          lt  summary gt           lt param name  OriginalFileLocation  gt Image location lt  param gt           lt param name  heigth  gt new height lt  param gt           lt param name  width  gt new width lt  param gt           lt param name  keepAspectRatio  gt keep the aspect ratio lt  param gt           lt returns gt image with new dimentions lt  returns gt      public Image resizeImageFromFile String OriginalFileLocation  int heigth  int width  Boolean keepAspectRatio                return resizeImageFromFile OriginalFileLocation  heigth  width  keepAspectRatio  false           Now are the last two booleans optional to set  Call the function like this   System Drawing Image ResizedImage   resizeImageFromFile imageLocation  800  400  true  true

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This is the code that I worked out for a specific requirement ie  the destination is always in landscape ratio  It should give you a good start   public Image ResizeImage Image source  RectangleF destinationBounds        RectangleF sourceBounds   new RectangleF 0 0f 0 0f  float source Width   float source Height       RectangleF scaleBounds   new RectangleF         Image destinationImage   new Bitmap  int destinationBounds Width   int destinationBounds Height       Graphics graph   Graphics FromImage destinationImage       graph InterpolationMode           System Drawing Drawing2D InterpolationMode HighQualityBicubic          Fill with background color     graph FillRectangle new SolidBrush System Drawing Color White   destinationBounds        float resizeRatio  sourceRatio      float scaleWidth  scaleHeight       sourceRatio    float source Width    float source Height       if  sourceRatio  gt   1 0f                  landscape         resizeRatio   destinationBounds Width   sourceBounds Width          scaleWidth   destinationBounds Width          scaleHeight   sourceBounds Height   resizeRatio          float trimValue   destinationBounds Height - scaleHeight          graph DrawImage source  0   trimValue   2   destinationBounds Width  scaleHeight             else                 portrait         resizeRatio   destinationBounds Height sourceBounds Height          scaleWidth   sourceBounds Width   resizeRatio          scaleHeight   destinationBounds Height          float trimValue   destinationBounds Width - scaleWidth          graph DrawImage source   trimValue   2   0  scaleWidth  destinationBounds Height              return destinationImage

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If you re working with a BitmapSource   var resizedBitmap   new TransformedBitmap      bitmapSource      new ScaleTransform scaleX  scaleY      If you want finer control over quality  run this first   RenderOptions SetBitmapScalingMode      bitmapSource      BitmapScalingMode HighQuality      Default is BitmapScalingMode Linear which is equivalent to BitmapScalingMode LowQuality

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This will perform a high quality resize        lt summary gt      Resize the image to the specified width and height       lt  summary gt       lt param name  image  gt The image to resize  lt  param gt       lt param name  width  gt The width to resize to  lt  param gt       lt param name  height  gt The height to resize to  lt  param gt       lt returns gt The resized image  lt  returns gt  public static Bitmap ResizeImage Image image  int width  int height        var destRect   new Rectangle 0  0  width  height       var destImage   new Bitmap width  height        destImage SetResolution image HorizontalResolution  image VerticalResolution        using  var graphics   Graphics FromImage destImage                 graphics CompositingMode   CompositingMode SourceCopy          graphics CompositingQuality   CompositingQuality HighQuality          graphics InterpolationMode   InterpolationMode HighQualityBicubic          graphics SmoothingMode   SmoothingMode HighQuality          graphics PixelOffsetMode   PixelOffsetMode HighQuality           using  var wrapMode   new ImageAttributes                          wrapMode SetWrapMode WrapMode TileFlipXY               graphics DrawImage image  destRect  0  0  image Width image Height  GraphicsUnit Pixel  wrapMode                        return destImage       wrapMode SetWrapMode WrapMode TileFlipXY  prevents ghosting around the image borders -- na  ve resizing will sample transparent pixels beyond the image boundaries  but by mirroring the image we can get a better sample  this setting is very noticeable  destImage SetResolution maintains DPI regardless of physical size -- may increase quality when reducing image dimensions or when printing Compositing controls how pixels are blended with the background -- might not be needed since we re only drawing one thing    graphics CompositingMode determines whether pixels from a source image overwrite or are combined with background pixels  SourceCopy specifies that when a color is rendered  it overwrites the background color  graphics CompositingQuality  determines the rendering quality level of layered images   graphics InterpolationMode  determines how intermediate values between two endpoints are calculated graphics SmoothingMode specifies whether lines  curves  and the edges of filled areas use smoothing  also called antialiasing  -- probably only works on vectors graphics PixelOffsetMode affects rendering quality when drawing the new image   Maintaining aspect ratio is left as an exercise for the reader  actually  I just don t think it s this function s job to do that for you    Also  this is a good article describing some of the pitfalls with image resizing  The above function will cover most of them  but you still have to worry about saving

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You could try net-vips  the C  binding for libvips  It s a lazy  streaming  demand-driven image processing library  so it can do operations like this without needing to load the whole image   For example  it comes with a handy image thumbnailer   Image image   Image Thumbnail  image jpg   300  300   image WriteToFile  my-thumbnail jpg      It also supports smart crop  a way of intelligently determining the most important part of the image and keeping it in focus while cropping the image  For example   Image image   Image Thumbnail  owl jpg   128  crop   attention    image WriteToFile  tn owl jpg      Where owl jpg is an off-centre composition     Gives this result     First it shrinks the image to get the vertical axis to 128 pixels  then crops down to 128 pixels across using the attention strategy  This one searches the image for features which might catch a human eye  see Smartcrop   for details

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