Java image resize maintain aspect ratio

Question

I have an image which I resize  if  width    null      height    null         try             scale image on disk         BufferedImage originalImage   ImageIO read file           int type   originalImage getType      0  BufferedImage TYPE INT ARGB                                                  originalImage getType             BufferedImage resizeImageJpg   resizeImage originalImage  type  200  200           ImageIO write resizeImageJpg   quot jpg quot   file              catch IOException e               System out println e getMessage                 This is how I resize the image  private static BufferedImage resizeImage BufferedImage originalImage  int type                                           Integer img width  Integer img height        BufferedImage resizedImage   new BufferedImage img width  img height  type       Graphics2D g   resizedImage createGraphics        g drawImage originalImage  0  0  img width  img height  null       g dispose         return resizedImage     Now the problem is  I also need to maintain aspect ratio  That is  I need the new 200 200 image to contain the new image scaled  Something like this   I tried some things but they didn t work out as expected  Any help is appreciated  Thanks alot

User · Answer

Load image   BufferedImage bufferedImage   ImageIO read file        Resize it   private BufferedImage resizeAndCrop BufferedImage bufferedImage  Integer width  Integer height         Mode mode    double  width    double  height  gt    double  bufferedImage getWidth      double  bufferedImage getHeight     Scalr Mode FIT TO WIDTH               Scalr Mode FIT TO HEIGHT       bufferedImage   Scalr resize bufferedImage  Scalr Method ULTRA QUALITY  mode  width  height        int x   0      int y   0       if  mode    Scalr Mode FIT TO WIDTH            y    bufferedImage getHeight   - height    2        else if  mode    Scalr Mode FIT TO HEIGHT            x    bufferedImage getWidth   - width    2             bufferedImage   Scalr crop bufferedImage  x  y  width  height        return bufferedImage      Using Scalr library    lt dependency gt       lt groupId gt org imgscalr lt  groupId gt       lt artifactId gt imgscalr-lib lt  artifactId gt       lt version gt 4 2 lt  version gt   lt  dependency gt

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All other answers show how to calculate the new image height in function of the new image width or vice-versa and how to resize the image using Java Image API  For those people who are looking for a straightforward solution I recommend any java image processing framework that can do this in a single line    The exemple below uses Marvin Framework      300 is the new width  The height is calculated to maintain aspect  scale image clone    image  300     Necessary import   import static marvin MarvinPluginCollection

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Here s a small piece of code that I wrote  it resizes the image to fit the container while keeping the image s original aspect ratio  It takes in as parameters the container s width  height and the image  You can modify it to fit your needs  It s simple and works fine for my applications   private Image scaleimage int wid  int hei  BufferedImage img       Image im   img      double scale      double imw   img getWidth        double imh   img getHeight        if  wid  gt  imw  amp  amp  hei  gt  imh           im   img       else if wid imw  lt  hei imh           scale   wid imw          im   img getScaledInstance  int   scale imw    int   scale imh   Image SCALE SMOOTH        else if  wid imw  gt  hei imh           scale   hei imh          im   img getScaledInstance  int   scale imw    int   scale imh   Image SCALE SMOOTH        else if  wid imw    hei imh           scale   wid imw          im   img getScaledInstance  int   scale imw    int   scale imh   Image SCALE SMOOTH              return im

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I have found the selected answer to have problems with upscaling  and so I have made  yet  another version  which I have tested    public static Point scaleFit Point src  Point bounds      int newWidth   src x    int newHeight   src y    double boundsAspectRatio   bounds y    double  bounds x    double srcAspectRatio   src y    double  src x        first check if we need to scale width   if  boundsAspectRatio  lt  srcAspectRatio           scale width to fit     newWidth   bounds x        scale height to maintain aspect ratio     newHeight    newWidth   src y    src x      else         scale height to fit instead     newHeight   bounds y        scale width to maintain aspect ratio     newWidth    newHeight   src x    src y         return new Point newWidth  newHeight       Written in Android terminology  -   as for the tests    Test public void scaleFit   throws Exception     final Point displaySize   new Point 1080  1920     assertEquals displaySize  Util scaleFit displaySize  displaySize      assertEquals displaySize  Util scaleFit new Point displaySize x   2  displaySize y   2   displaySize      assertEquals displaySize  Util scaleFit new Point displaySize x   2  displaySize y   2   displaySize      assertEquals new Point displaySize x  displaySize y   2   Util scaleFit new Point displaySize x   2  displaySize y   displaySize      assertEquals new Point displaySize x   2  displaySize y   Util scaleFit new Point displaySize x  displaySize y   2   displaySize      assertEquals new Point displaySize x  displaySize y   3   2   Util scaleFit new Point displaySize x   3  displaySize y   2   displaySize

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This is my solution      Change dimension of Image    public static Image resizeImage Image image  int scaledWidth  int scaledHeight  boolean preserveRatio           if  preserveRatio             double imageHeight   image getHeight            double imageWidth   image getWidth             if  imageHeight scaledHeight  gt  imageWidth scaledWidth                scaledWidth    int   scaledHeight   imageWidth   imageHeight             else               scaledHeight    int   scaledWidth   imageHeight   imageWidth                                                  BufferedImage inputBufImage   SwingFXUtils fromFXImage image  null               creates output image     BufferedImage outputBufImage   new BufferedImage scaledWidth  scaledHeight  inputBufImage getType                   scales the input image to the output image     Graphics2D g2d   outputBufImage createGraphics        g2d drawImage inputBufImage  0  0  scaledWidth  scaledHeight  null       g2d dispose              return SwingFXUtils toFXImage outputBufImage  null

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You will want to check out Image getScaledInstance    and more in this answer  How to improve the performance of g drawImage   method for resizing images

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try this  float rateX     float jpDisplayImagen getWidth    float img getWidth    float rateY    float jpDisplayImagen getHeight    float img getHeight    if  rateX gt rateY       int W  int  img getWidth   rateY       int H  int  img getHeight   rateY       jpDisplayImagen getGraphics   drawImage img  0  0 W H  null     else      int W  int  img getWidth   rateX       int H  int  img getHeight   rateX       jpDisplayImagen getGraphics   drawImage img  0  0 W H  null

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public class ImageTransformation    public static final String PNG    png    public static byte   resize FileItem fileItem  int width  int height         try           ResampleOp resampleOp   new ResampleOp width  height           BufferedImage scaledImage   resampleOp filter ImageIO read fileItem getInputStream     null            ByteArrayOutputStream baos   new ByteArrayOutputStream            ImageIO write scaledImage  PNG  baos            return baos toByteArray          catch  Exception ex            throw new MapsException  An error occured during image resizing    ex             public static byte   resizeAdjustMax FileItem fileItem  int maxWidth  int maxHeight         try           BufferedInputStream bis   new BufferedInputStream fileItem getInputStream               BufferedImage bufimg   ImageIO read bis                 check size of image          int img width   bufimg getWidth            int img height   bufimg getHeight            if img width  gt  maxWidth    img height  gt  maxHeight                float factx    float  img width   maxWidth              float facty    float  img height   maxHeight              float fact    factx gt facty    factx   facty              img width    int    int  img width   fact               img height    int    int  img height   fact                      return resize fileItem img width  img height          catch  Exception ex            throw new MapsException  An error occured during image resizing    ex

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Just add one more block to Ozzy s code so the thing looks like this   public static Dimension getScaledDimension Dimension imgSize Dimension boundary         int original width   imgSize width      int original height   imgSize height      int bound width   boundary width      int bound height   boundary height      int new width   original width      int new height   original height          first check if we need to scale width     if  original width  gt  bound width              scale width to fit         new width   bound width            scale height to maintain aspect ratio         new height    new width   original height    original width                then check if we need to scale even with the new height     if  new height  gt  bound height              scale height to fit instead         new height   bound height            scale width to maintain aspect ratio         new width    new height   original width    original height               upscale if original is smaller     if  original width  lt  bound width              scale width to fit         new width   bound width            scale height to maintain aspect ratio         new height    new width   original height    original width             return new Dimension new width  new height

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Here we go  Dimension imgSize   new Dimension 500  100   Dimension boundary   new Dimension 200  200    Function to return the new size depending on the boundary  public static Dimension getScaledDimension Dimension imgSize  Dimension boundary         int original width   imgSize width      int original height   imgSize height      int bound width   boundary width      int bound height   boundary height      int new width   original width      int new height   original height          first check if we need to scale width     if  original width  gt  bound width              scale width to fit         new width   bound width            scale height to maintain aspect ratio         new height    new width   original height    original width                then check if we need to scale even with the new height     if  new height  gt  bound height              scale height to fit instead         new height   bound height            scale width to maintain aspect ratio         new width    new height   original width    original height             return new Dimension new width  new height      In case anyone also needs the image resizing code  here is a decent solution  If you re unsure about the above solution  there are different ways to achieve the same result

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Translated from here   Dimension getScaledDimension Dimension imageSize  Dimension boundary         double widthRatio   boundary getWidth     imageSize getWidth        double heightRatio   boundary getHeight     imageSize getHeight        double ratio   Math min widthRatio  heightRatio        return new Dimension  int   imageSize width    ratio                             int   imageSize height   ratio        You can also use imgscalr to resize images while maintaining aspect ratio   BufferedImage resizeMe   ImageIO read new File  orig jpg     Dimension newMaxSize   new Dimension 255  255   BufferedImage resizedImg   Scalr resize resizeMe  Method QUALITY                                          newMaxSize width  newMaxSize height

[java] Java image resize, maintain aspect ratio

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