Resize a large bitmap file to scaled output file on Android

Question

I have a large bitmap  say 3888x2592  in a file  Now  I want to resize that bitmap to 800x533 and save it to another file  I normally would scale the bitmap by calling Bitmap createBitmap method but it needs a source bitmap as the first argument  which I can t provide because loading the original image into a Bitmap object would of course exceed the memory  see here  for example    I also can t read the bitmap with  for example  BitmapFactory decodeFile file  options   providing a BitmapFactory Options inSampleSize  because I want to resize it to an exact width and height  Using inSampleSize would resize the bitmap to 972x648  if I use inSampleSize 4  or to 778x518  if I use inSampleSize 5  which isn t even a power of 2    I would also like to avoid reading the image using inSampleSize with  for example  972x648 in a first step and then resizing it to exactly 800x533 in a second step  because the quality would be poor compared to a direct resizing of the original image   To sum up my question  Is there a way to read a large image file with 10MP or more and save it to a new image file  resized to a specific new width and height  without getting an OutOfMemory exception   I also tried BitmapFactory decodeFile file  options  and setting the Options outHeight and Options outWidth values manually to 800 and 533  but it doesn t work that way

User · Answer

I used code like this     String filePath Environment getExternalStorageDirectory     test image jpg     BitmapFactory Options options new BitmapFactory Options      InputStream is new FileInputStream filePath     BitmapFactory decodeStream is  null  options     is close      is new FileInputStream filePath        here w and h are the desired width and height   options inSampleSize Math max options outWidth 460  options outHeight 288     Max 460 x 288 is my desired         bmp is the resized bitmap   Bitmap bmp BitmapFactory decodeStream is  null  options     is close      Log d Constants TAG   Scaled bitmap bytes    bmp getRowBytes      width   bmp getWidth      height   bmp getHeight       I tried original image is 1230 x 1230  and got bitmap says is 330 x 330  And if tried 2590 x 3849  I ll got OutOfMemoryError   I traced it  it still throw OutOfMemoryError on line  BitmapFactory decodeStream is  null  options     if original bitmap too large

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This is  Mojo Risin s and  Ofir s solutions  combined   This will give you a proportionally resized image with the boundaries of max width and max height    It only reads meta data to get the original size  options inJustDecodeBounds  It uses a rought resize to save memory  itmap createScaledBitmap  It uses a precisely resized image based on the rough Bitamp created earlier    For me it has been performing fine on 5 MegaPixel images an below   try       int inWidth   0      int inHeight   0       InputStream in   new FileInputStream pathOfInputImage           decode image size  decode metadata only  not the whole image      BitmapFactory Options options   new BitmapFactory Options        options inJustDecodeBounds   true      BitmapFactory decodeStream in  null  options       in close        in   null          save width and height     inWidth   options outWidth      inHeight   options outHeight          decode full image pre-resized     in   new FileInputStream pathOfInputImage       options   new BitmapFactory Options           calc rought re-size  this is no exact resize      options inSampleSize   Math max inWidth dstWidth  inHeight dstHeight          decode full image     Bitmap roughBitmap   BitmapFactory decodeStream in  null  options           calc exact destination size     Matrix m   new Matrix        RectF inRect   new RectF 0  0  roughBitmap getWidth    roughBitmap getHeight         RectF outRect   new RectF 0  0  dstWidth  dstHeight       m setRectToRect inRect  outRect  Matrix ScaleToFit CENTER       float   values   new float 9       m getValues values           resize bitmap     Bitmap resizedBitmap   Bitmap createScaledBitmap roughBitmap   int   roughBitmap getWidth     values 0     int   roughBitmap getHeight     values 4    true           save image     try               FileOutputStream out   new FileOutputStream pathOfOutputImage           resizedBitmap compress Bitmap CompressFormat JPEG  80  out             catch  Exception e                Log e  Image   e getMessage    e           catch  IOException e        Log e  Image   e getMessage    e

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I use Integer numberOfLeadingZeros to calculate the best sample size  better performance   Full code in kotlin    Throws IOException  class  fun File decodeBitmap options  BitmapFactory Options   Bitmap        return inputStream   use           BitmapFactory decodeStream it  null  options            Throws IOException  class  fun File decodeBitmapAtLeast           androidx annotation IntRange from   1  width  Int           androidx annotation IntRange from   1  height  Int    Bitmap        val options   BitmapFactory Options        options inJustDecodeBounds   true     decodeBitmap options       val ow   options outWidth     val oh   options outHeight      if  ow    -1    oh    -1  return null      val w   ow   width     val h   oh   height      if  w  gt  1  amp  amp  h  gt  1            val p   31 - maxOf Integer numberOfLeadingZeros w   Integer numberOfLeadingZeros h           options inSampleSize   1 shl maxOf 0  p            options inJustDecodeBounds   false     return decodeBitmap options

User · Answer

No   I d love for someone to correct me  but I accepted the load resize approach you tried as a compromise   Here are the steps for anyone browsing    Calculate the maximum possible inSampleSize that still yields an image larger than your target  Load the image using BitmapFactory decodeFile file  options   passing inSampleSize as an option  Resize to the desired dimensions using Bitmap createScaledBitmap

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Bitmap yourBitmap   Bitmap resized   Bitmap createScaledBitmap yourBitmap  newWidth  newHeight  true     or    resized   Bitmap createScaledBitmap yourBitmap  int  yourBitmap getWidth   0 8    int  yourBitmap getHeight   0 8   true

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Here is an article that takes a different approach to resizing  It will attempt to load the largest possible bitmap into memory based on available memory in the process and then perform the transforms   http   bricolsoftconsulting com 2012 12 07 handling-large-images-on-android

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When i have large bitmaps and i want to decode them resized i use the following  BitmapFactory Options options   new BitmapFactory Options    InputStream is   null  is   new FileInputStream path to file   BitmapFactory decodeStream is null options   is close    is   new FileInputStream path to file      here w and h are the desired width and height options inSampleSize   Math max options outWidth w  options outHeight h      bitmap is the resized bitmap Bitmap bitmap   BitmapFactory decodeStream is null options

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This worked for me  The function gets a path to a file on the sd card and returns a Bitmap in the maximum displayable size  The code is from Ofir with some changes like image file on sd instead a Ressource and the witdth and heigth are get from the Display Object   private Bitmap makeBitmap String path         try           final int IMAGE MAX SIZE   1200000     1 2MP           resource   getResources                Decode image size         BitmapFactory Options options   new BitmapFactory Options            options inJustDecodeBounds   true          BitmapFactory decodeFile path  options            int scale   1          while   options outWidth   options outHeight     1   Math pow scale  2    gt                  IMAGE MAX SIZE                scale                      Log d  TAG    scale       scale      orig-width      options outWidth      orig-height      options outHeight            Bitmap pic   null          if  scale  gt  1                scale--                 scale to max possible inSampleSize that still yields an image                larger than target             options   new BitmapFactory Options                options inSampleSize   scale              pic   BitmapFactory decodeFile path  options                   resize to desired dimensions              Display display   getWindowManager   getDefaultDisplay                Point size   new Point                display getSize size               int width   size y              int height   size x                 int height   imageView getHeight                  int width   imageView getWidth                Log d  TAG    1th scale operation dimenions - width      width      height      height                double y   Math sqrt IMAGE MAX SIZE                          double  width    height                double x    y   height    width               Bitmap scaledBitmap   Bitmap createScaledBitmap pic   int  x   int  y  true               pic recycle                pic   scaledBitmap               System gc              else               pic   BitmapFactory decodeFile path                      Log d  TAG    bitmap size - width     pic getWidth        height      pic getHeight             return pic         catch  Exception e            Log e  TAG   e getMessage   e           return null

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There is a great article about this exact issue on the Android developer website  Loading Large Bitmaps Efficiently

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Here is the code I use which doesn t have any issues decoding large images in memory on Android   I have been able to decode images larger then 20MB as long as my input parameters are around 1024x1024  You can save the returned bitmap to another file   Below this method is another method which I also use to scale images to a new bitmap   Feel free to use this code as you wish                                                                                     public decode - decode the image into a Bitmap         param xyDimension               - The max XY Dimension before the image is scaled down - XY                 1080x1080 and Image   2000x2000 image will be scaled down to a               value equal or less then set value      param bitmapConfig               - Bitmap Config Valid values     Bitmap Config ARGB 4444                Bitmap Config RGB 565  Bitmap Config ARGB 8888           return Bitmap - Image - a value of  null  if there is an issue decoding            image dimension         throws FileNotFoundException                - If the image has been removed while this operation is                taking place     public Bitmap decode  int xyDimension  Bitmap Config bitmapConfig   throws FileNotFoundException          The Bitmap to return given a Uri to a file     Bitmap bitmap   null      File file   null      FileInputStream fis   null      InputStream in   null          Try to decode the Uri     try                  Initialize scale to no real scaling factor         double scale   1              Get FileInputStream to get a FileDescriptor         file   new File  this imageUri getPath               fis   new FileInputStream  file            FileDescriptor fd   fis getFD                Get a BitmapFactory Options object         BitmapFactory Options o   new BitmapFactory Options                Decode only the image size         o inJustDecodeBounds   true          o inPreferredConfig   bitmapConfig              Decode to get Width  amp  Height of image only         BitmapFactory decodeFileDescriptor  fd  null  o            BitmapFactory decodeStream  null             if  o outHeight  gt  xyDimension    o outWidth  gt  xyDimension                            Change the scale if the image is larger then desired image                max size             scale   Math pow  2   int  Math round  Math log  xyDimension    double  Math max  o outHeight  o outWidth       Math log  0 5                              Decode with inSampleSize scale will either be 1 or calculated value         o inJustDecodeBounds   false          o inSampleSize    int  scale              Decode the Uri for real with the inSampleSize         in   new BufferedInputStream  fis            bitmap   BitmapFactory decodeStream  in  null  o              catch  OutOfMemoryError e                 Log e  DEBUG TAG   decode   OutOfMemoryError             e printStackTrace              catch  NullPointerException e                 Log e  DEBUG TAG   decode   NullPointerException             e printStackTrace              catch  RuntimeException e                 Log e  DEBUG TAG   decode   RuntimeException             e printStackTrace              catch  FileNotFoundException e                 Log e  DEBUG TAG   decode   FileNotFoundException             e printStackTrace              catch  IOException e                 Log e  DEBUG TAG   decode   IOException             e printStackTrace                  Save memory     file   null      fis   null      in   null       return bitmap        decode   NOTE  Methods have nothing to do with each other except createScaledBitmap calls decode method above  Note width and height can change from original image                                                                                     public createScaledBitmap - Creates a new bitmap  scaled from an existing    bitmap          param dstWidth               - Scale the width to this dimension     param dstHeight               - Scale the height to this dimension     param xyDimension               - The max XY Dimension before the original image is scaled               down - XY   1080x1080 and Image   2000x2000 image will be               scaled down to a value equal or less then set value      param bitmapConfig               - Bitmap Config Valid values     Bitmap Config ARGB 4444                Bitmap Config RGB 565  Bitmap Config ARGB 8888           return Bitmap - Image scaled - a value of  null  if there is an issue         public Bitmap createScaledBitmap  int dstWidth  int dstHeight  int xyDimension  Bitmap Config bitmapConfig         Bitmap scaledBitmap   null       try               Bitmap bitmap   this decode  xyDimension  bitmapConfig                Create an empty Bitmap which will contain the new scaled bitmap            This scaled bitmap should be the size we want to scale the            original bitmap too         scaledBitmap   Bitmap createBitmap  dstWidth  dstHeight  bitmapConfig             float ratioX   dstWidth    float  bitmap getWidth            float ratioY   dstHeight    float  bitmap getHeight            float middleX   dstWidth   2 0f          float middleY   dstHeight   2 0f              Used to for scaling the image         Matrix scaleMatrix   new Matrix            scaleMatrix setScale  ratioX  ratioY  middleX  middleY                Used to do the work of scaling         Canvas canvas   new Canvas  scaledBitmap            canvas setMatrix  scaleMatrix            canvas drawBitmap  bitmap  middleX - bitmap getWidth     2  middleY - bitmap getHeight     2  new Paint  Paint FILTER BITMAP FLAG                catch  IllegalArgumentException e                 Log e  DEBUG TAG   createScaledBitmap   IllegalArgumentException             e printStackTrace              catch  NullPointerException e                 Log e  DEBUG TAG   createScaledBitmap   NullPointerException             e printStackTrace              catch  FileNotFoundException e                 Log e  DEBUG TAG   createScaledBitmap   FileNotFoundException             e printStackTrace               return scaledBitmap       End createScaledBitmap

User · Answer

After reading these answers and android documentation here s the code to resize bitmap without loading it into memory   public Bitmap getResizedBitmap int targetW  int targetH   String imagePath            Get the dimensions of the bitmap     BitmapFactory Options bmOptions   new BitmapFactory Options          inJustDecodeBounds   true  lt -- will not load the bitmap into memory     bmOptions inJustDecodeBounds   true      BitmapFactory decodeFile imagePath  bmOptions       int photoW   bmOptions outWidth      int photoH   bmOptions outHeight          Determine how much to scale down the image     int scaleFactor   Math min photoW targetW  photoH targetH           Decode the image file into a Bitmap sized to fill the View     bmOptions inJustDecodeBounds   false      bmOptions inSampleSize   scaleFactor      bmOptions inPurgeable   true       Bitmap bitmap   BitmapFactory decodeFile imagePath  bmOptions       return bitmap

User · Answer

Why not use the API   int h   48     height in pixels int w   48     width in pixels     Bitmap scaled   Bitmap createScaledBitmap largeBitmap  w  h  true

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If you absolutely want to do one step resize you could probably load entire bitmap if android largeHeap   true but as you can see this is not really advisable   From docs  android largeHeap Whether your application s processes should be created with a large Dalvik heap  This applies to all processes created for the application  It only applies to the first application loaded into a process  if you re using a shared user ID to allow multiple applications to use a process  they all must use this option consistently or they will have unpredictable results  Most apps should not need this and should instead focus on reducing their overall memory usage for improved performance  Enabling this also does not guarantee a fixed increase in available memory  because some devices are constrained by their total available memory

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Taking into account that you want to resize to exact size and want to keep as much quality as needed I think you should try this    Find out the size of the resized image with call of BitmapFactory decodeFile and providing the checkSizeOptions inJustDecodeBounds Calculate the maximum possible inSampleSize you can use on your device to not exceed the memory  bitmapSizeInBytes   2 width height  Generally for your picture inSampleSize 2 would be fine since you will need only 2 1944x1296  4 8Mb  which should feet in memory Use BitmapFactory decodeFile with inSampleSize to load the Bitmap Scale the bitmap to exact size     Motivation  multiple-steps scaling could give you higher quality picture  however there is no guarantee that it will work better than using high inSampleSize   Actually  I think that you also can use inSampleSize like 5  not pow of 2  to have direct scaling in one operation  Or just use 4 and then you can just use that image in UI  if you send it to server - than you can do scaling to exact size on server side which allow you to use advanced scaling techniques   Notes  if the Bitmap loaded in step-3 is at least 4 times larger  so the 4 targetWidth  lt  width  you probably can use several resizing to achieve better quality   at least that works in generic java  in android you don t have the option to specify the interpolation used for scaling http   today java net pub a today 2007 04 03 perils-of-image-getscaledinstance html

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I don t know if my solution is best practice  but I achieved loading a bitmap with my desired scaling by using the inDensity and inTargetDensity options  inDensity is 0 initially when not loading a drawable resource  so this approach is for loading non resource images   The variables imageUri  maxImageSideLength and context are parameters of my method  I posted only the method implementation without the wrapping AsyncTask for clarity               ContentResolver resolver   context getContentResolver                InputStream is              try                   is   resolver openInputStream imageUri                 catch  FileNotFoundException e                    Log e TAG   Image not found    e                   return null                            Options opts   new Options                opts inJustDecodeBounds   true              BitmapFactory decodeStream is  null  opts                   scale the image             float maxSideLength   maxImageSideLength              float scaleFactor   Math min maxSideLength   opts outWidth  maxSideLength   opts outHeight                  do not upscale              if  scaleFactor  lt  1                    opts inDensity   10000                  opts inTargetDensity    int    float  opts inDensity   scaleFactor                             opts inJustDecodeBounds   false               try                   is close                  catch  IOException e                       ignore                           try                   is   resolver openInputStream imageUri                 catch  FileNotFoundException e                    Log e TAG   Image not found    e                   return null                            Bitmap bitmap   BitmapFactory decodeStream is  null  opts               try                   is close                  catch  IOException e                       ignore                            return bitmap

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To scale the image the  correct  way  without skipping any pixels  you d have to hook into the image decoder to perform the down-sampling row by row  Android  and the Skia library that underlies it  provides no such hooks  so you d have to roll your own  Assuming you re talking jpeg images  your best bet would be to use libjpeg directly  in C   Given the complexities involved  using the two-step subsample-then-rescale is probably best for image-preview type apps

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Resize the bitmap using the following code      public static Bitmap decodeFile File file  int reqWidth  int reqHeight           First decode with inJustDecodeBounds true to check dimensions     final BitmapFactory Options options   new BitmapFactory Options        options inJustDecodeBounds   true              BitmapFactory decodeFile file getPath    options           Calculate inSampleSize     options inSampleSize   calculateInSampleSize options  reqWidth  reqHeight           Decode bitmap with inSampleSize set     options inJustDecodeBounds   false      return BitmapFactory decodeFile file getPath    options             private static int calculateInSampleSize      BitmapFactory Options options  int reqWidth  int reqHeight           Raw height and width of image     final int height   options outHeight      final int width   options outWidth      int inSampleSize   1       if  height  gt  reqHeight    width  gt  reqWidth                Calculate ratios of height and width to requested height and width         final int heightRatio   Math round  float  height    float  reqHeight           final int widthRatio   Math round  float  width    float  reqWidth               Choose the smallest ratio as inSampleSize value  this will guarantee            a final image with both dimensions larger than or equal to the            requested height and width          inSampleSize   heightRatio  lt  widthRatio   heightRatio   widthRatio               return inSampleSize             The same is also explained in the following tip trick  http   www codeproject com Tips 625810 Android-Image-Operations-Using-BitmapFactory

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Justin answer translated to code  works perfect for me    private Bitmap getBitmap String path     Uri uri   getImageUri path   InputStream in   null  try       final int IMAGE MAX SIZE   1200000     1 2MP     in   mContentResolver openInputStream uri           Decode image size     BitmapFactory Options options   new BitmapFactory Options        options inJustDecodeBounds   true      BitmapFactory decodeStream in  null  options       in close           int scale   1      while   options outWidth   options outHeight     1   Math pow scale  2    gt             IMAGE MAX SIZE           scale              Log d TAG   scale       scale      orig-width      options outWidth              orig-height      options outHeight        Bitmap resultBitmap   null      in   mContentResolver openInputStream uri       if  scale  gt  1            scale--             scale to max possible inSampleSize that still yields an image            larger than target         options   new BitmapFactory Options            options inSampleSize   scale          resultBitmap   BitmapFactory decodeStream in  null  options               resize to desired dimensions         int height   resultBitmap getHeight            int width   resultBitmap getWidth            Log d TAG   1th scale operation dimenions - width      width                 height      height            double y   Math sqrt IMAGE MAX SIZE                      double  width    height            double x    y   height    width           Bitmap scaledBitmap   Bitmap createScaledBitmap resultBitmap   int  x               int  y  true           resultBitmap recycle            resultBitmap   scaledBitmap           System gc          else           resultBitmap   BitmapFactory decodeStream in             in close         Log d TAG   bitmap size - width     resultBitmap getWidth        height              resultBitmap getHeight         return resultBitmap    catch  IOException e        Log e TAG  e getMessage   e       return null

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Above code made a little cleaner  InputStreams have finally close wrapping to ensure they get closed as well    Note Input  InputStream is  int w  int h   Output  Bitmap      try                final int inWidth          final int inHeight           final File tempFile   new File temp  System currentTimeMillis     is toString       temp                            final FileOutputStream tempOut   new FileOutputStream tempFile                StreamUtil copyTo is  tempOut                tempOut close                                         final InputStream in   new FileInputStream tempFile               final BitmapFactory Options options   new BitmapFactory Options                 try                       decode image size  decode metadata only  not the whole image                  options inJustDecodeBounds   true                  BitmapFactory decodeStream in  null  options                              finally                   in close                                  save width and height             inWidth   options outWidth              inHeight   options outHeight                      final Bitmap roughBitmap                             decode full image pre-resized             final InputStream in   new FileInputStream tempFile                try                    final BitmapFactory Options options   new BitmapFactory Options                       calc rought re-size  this is no exact resize                  options inSampleSize   Math max inWidth w  inHeight h                      decode full image                 roughBitmap   BitmapFactory decodeStream in  null  options                              finally                   in close                               tempFile delete                        float   values   new float 9                              calc exact destination size             Matrix m   new Matrix                RectF inRect   new RectF 0  0  roughBitmap getWidth    roughBitmap getHeight                 RectF outRect   new RectF 0  0  w  h               m setRectToRect inRect  outRect  Matrix ScaleToFit CENTER               m getValues values                          resize bitmap         final Bitmap resizedBitmap   Bitmap createScaledBitmap roughBitmap   int   roughBitmap getWidth     values 0     int   roughBitmap getHeight     values 4    true            return resizedBitmap             catch  IOException e             logger error  Error     e           throw new ResourceException  could not create bitmap

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Acknowledging the other excellent answer so far  the best code I ve seen yet for this is in the documentation for the photo taking tool   See the section entitled  Decode a Scaled Image    http   developer android com training camera photobasics html  The solution it proposes is a resize then scale solution like the others here  but it s quite neat   I ve copied the code below as a ready-to-go function for convenience   private void setPic String imagePath  ImageView destination        int targetW   destination getWidth        int targetH   destination getHeight           Get the dimensions of the bitmap     BitmapFactory Options bmOptions   new BitmapFactory Options        bmOptions inJustDecodeBounds   true      BitmapFactory decodeFile imagePath  bmOptions       int photoW   bmOptions outWidth      int photoH   bmOptions outHeight          Determine how much to scale down the image     int scaleFactor   Math min photoW targetW  photoH targetH           Decode the image file into a Bitmap sized to fill the View     bmOptions inJustDecodeBounds   false      bmOptions inSampleSize   scaleFactor      bmOptions inPurgeable   true       Bitmap bitmap   BitmapFactory decodeFile imagePath  bmOptions       destination setImageBitmap bitmap

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This may be useful for someone else looking at this question  I rewrote Justin s code to allow the method to receive the target size object required as well  This works very well when using Canvas  All credit should go to JUSTIN for his great initial code       private Bitmap getBitmap int path  Canvas canvas             Resources resource   null          try               final int IMAGE MAX SIZE   1200000     1 2MP             resource   getResources                    Decode image size             BitmapFactory Options options   new BitmapFactory Options                options inJustDecodeBounds   true              BitmapFactory decodeResource resource  path  options                int scale   1              while   options outWidth   options outHeight     1   Math pow scale  2    gt                     IMAGE MAX SIZE                   scale                              Log d  TAG    scale       scale      orig-width      options outWidth      orig-height      options outHeight                Bitmap pic   null              if  scale  gt  1                    scale--                     scale to max possible inSampleSize that still yields an image                    larger than target                 options   new BitmapFactory Options                    options inSampleSize   scale                  pic   BitmapFactory decodeResource resource  path  options                       resize to desired dimensions                 int height   canvas getHeight                    int width   canvas getWidth                    Log d  TAG    1th scale operation dimenions - width      width      height      height                    double y   Math sqrt IMAGE MAX SIZE                              double  width    height                    double x    y   height    width                   Bitmap scaledBitmap   Bitmap createScaledBitmap pic   int  x   int  y  true                   pic recycle                    pic   scaledBitmap                   System gc                  else                   pic   BitmapFactory decodeResource resource  path                              Log d  TAG    bitmap size - width     pic getWidth        height      pic getHeight                 return pic            catch  Exception e                Log e  TAG   e getMessage   e               return null                    Justin s code is VERY effective at reducing the overhead of working with large Bitmaps

[android] Resize a large bitmap file to scaled output file on Android

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