0

In my android application i am using whatsapp like image compression and after that i convert the compressed image bitmap to string using Base64 encoding,what i noticed is that when i compress a 5mb image and save it in another locations its just of 60kb or 70kb something like that and the Base64 encoded string is taking 500kb or 600kb for the same image, why its like that? Is there any way to convert the compressed image to string with its same size.Below is my code.

Bitmap bitmapImg;

    if (requestCode == FILE_SELECT_CODE) {
        if(data!= null) {
            try {
                Uri selectedImageUri = data.getData();
                String mimeType = getContentResolver().getType(selectedImageUri);

                compressImage(selectedImageUri);

            // Converting compressed bitmap to string
                ByteArrayOutputStream byteArrayOS = new ByteArrayOutputStream();
                bitmapImg.compress(Bitmap.CompressFormat.PNG, 100, byteArrayOS);
                String strBitmap = Base64.encodeToString(byteArrayOS.toByteArray(), Base64.DEFAULT);

            } catch (Exception e) {
                e.printStackTrace();
            }
        }

    }

    private String compressImage(Uri selImageUri) {
        String fileStrName = null;
        bitmapImg = null;
        try {
            String filePath = getRealPathFromURI(selImageUri);
            BitmapFactory.Options options = new BitmapFactory.Options();

    //      by setting this field as true, the actual bitmap pixels are not loaded in the memory. Just the bounds are loaded. If
    //      you try the use the bitmap here, you will get null.
            options.inJustDecodeBounds = true;
            Bitmap bmpTemp = BitmapFactory.decodeFile(filePath, options);

            int actualHeight = options.outHeight;
            int actualWidth = options.outWidth;

    //      max Height and width values of the compressed image is taken as 816x612

            float maxHeight = 816.0f;
            float maxWidth = 612.0f;
            float imgRatio = actualWidth / actualHeight;
            float maxRatio = maxWidth / maxHeight;

    //      width and height values are set maintaining the aspect ratio of the image

            if (actualHeight > maxHeight || actualWidth > maxWidth) {
                if (imgRatio < maxRatio) {
                    imgRatio = maxHeight / actualHeight;
                    actualWidth = (int) (imgRatio * actualWidth);
                    actualHeight = (int) maxHeight;
                } else if (imgRatio > maxRatio) {
                    imgRatio = maxWidth / actualWidth;
                    actualHeight = (int) (imgRatio * actualHeight);
                    actualWidth = (int) maxWidth;
                } else {
                    actualHeight = (int) maxHeight;
                    actualWidth = (int) maxWidth;
                }
            }

    //      setting inSampleSize value allows to load a scaled down version of the original image

            options.inSampleSize = calculateInSampleSize(options, actualWidth, actualHeight);
    //      inJustDecodeBounds set to false to load the actual bitmap

            options.inJustDecodeBounds = false;

    //      this options allow android to claim the bitmap memory if it runs low on memory

            options.inPurgeable = true;
            options.inInputShareable = true;
            options.inTempStorage = new byte[16 * 1024];

            try {
    //          load the bitmap from its path

                bmpTemp = BitmapFactory.decodeFile(filePath, options);
            } catch (OutOfMemoryError exception) {
                exception.printStackTrace();
            }
            try {
                bitmapImg = Bitmap.createBitmap(actualWidth, actualHeight, Bitmap.Config.ARGB_8888);
            } catch (OutOfMemoryError exception) {
                exception.printStackTrace();
            }

            float ratioX = actualWidth / (float) options.outWidth;
            float ratioY = actualHeight / (float) options.outHeight;
            float middleX = actualWidth / 2.0f;
            float middleY = actualHeight / 2.0f;

            Matrix scaleMatrix = new Matrix();
            scaleMatrix.setScale(ratioX, ratioY, middleX, middleY);

            Canvas canvas = new Canvas(bitmapImg);
            canvas.setMatrix(scaleMatrix);
            canvas.drawBitmap(bmpTemp, middleX - bmpTemp.getWidth() / 2, middleY - bmpTemp.getHeight() / 2, new Paint(Paint.FILTER_BITMAP_FLAG));

    //      check the rotation of the image and display it properly

            ExifInterface exif;
            try {
                exif = new ExifInterface(filePath);

                int orientation = exif.getAttributeInt(ExifInterface.TAG_ORIENTATION, 0);
                Matrix matrix = new Matrix();
                if (orientation == 6) {
                    matrix.postRotate(90);
                } else if (orientation == 3) {
                    matrix.postRotate(180);
                } else if (orientation == 8) {
                    matrix.postRotate(270);
                }
                bitmapImg = Bitmap.createBitmap(bitmapImg, 0, 0, bitmapImg.getWidth(), bitmapImg.getHeight(), matrix, true);
            } catch (IOException e) {
                e.printStackTrace();
            } 
            FileOutputStream out = null;
            String filename = getFilename();
            try {
                out = new FileOutputStream(filename);

    //          write the compressed bitmap at the destination specified by filename.
                bitmapImg.compress(Bitmap.CompressFormat.JPEG, 80, out);

            } catch (FileNotFoundException e) {
                e.printStackTrace();
            }

        } catch (Exception e) {
            e.printStackTrace();
        }

        return fileStrName;
    }

    public int calculateInSampleSize(BitmapFactory.Options options, int reqWidth, int reqHeight) {
        final int height = options.outHeight;
        final int width = options.outWidth;
        int inSampleSize = 1;

        if (height > reqHeight || width > reqWidth) {
            final int heightRatio = Math.round((float) height/ (float) reqHeight);
            final int widthRatio = Math.round((float) width / (float) reqWidth);
            inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
        }
        final float totalPixels = width * height;
        final float totalReqPixelsCap = reqWidth * reqHeight * 2;
        while (totalPixels / (inSampleSize * inSampleSize) > totalReqPixelsCap) {
            inSampleSize++;
        }

        return inSampleSize;
    }

    private String getRealPathFromURI(Uri contentUri) {
        Cursor cursor = getContentResolver().query(contentUri, null, null, null, null);
        if (cursor == null) {
            return contentUri.getPath();
        } else {
            cursor.moveToFirst();
            int index = cursor.getColumnIndex(MediaStore.Images.ImageColumns.DATA);
            return cursor.getString(index);
        }
    }

    public String getFilename() {
        File file = new File(Environment.getExternalStorageDirectory().getPath(), "MyFolder/Images");
        if (!file.exists()) {
            file.mkdirs();
        }
        String uriSting = (file.getAbsolutePath() + "/" + System.currentTimeMillis() + ".jpg");
        return uriSting;

    }

Here the compressed image is of size 60kb or 70kb but when I save the strBitmap to database its taking 500kb or 600kb.How can i convert the compressed bitmap with the same size to string.

KJEjava48
  • 1,967
  • 7
  • 40
  • 69
  • Check this out: http://stackoverflow.com/questions/11402329/base64-encoded-image-size – Faraz Apr 19 '17 at 06:01
  • 1
    @FAЯAƸ But there it says its approximately 37% larger but its not like that in my case.. – KJEjava48 Apr 19 '17 at 06:10
  • Currently, you have a **plain string**, meaning that each byte weights a full byte. Try **compressing it** (zip it ot crunch it somehow). You'll regain the lost compression (strings are highly comprimible). – Phantômaxx Apr 19 '17 at 07:16

1 Answers1

2

There's one big difference in your images though.

The image you store as a file is stored as a JPEG

bitmapImg.compress(Bitmap.CompressFormat.JPEG, 80, out);

while the Base64 encoded string is a PNG

bitmapImg.compress(Bitmap.CompressFormat.PNG, 100, byteArrayOS);

This can explain the size differences. Another thing could be, that bitmapImg changed it's contents inbetween both compressions as well.

tynn
  • 38,113
  • 8
  • 108
  • 143
  • Does png and jpeg format have that much size difference?? – KJEjava48 Apr 19 '17 at 06:45
  • They can have such big size differences. It also could happen that a JPG is bigger than PNG. But with your starting 5MB it's not too likely. – tynn Apr 19 '17 at 06:47
  • So how can i convert PNG formatted bitmap to a small sized string ?? – KJEjava48 Apr 19 '17 at 06:50
  • Hmm.U are right when i compress the file to png format its of size 350 kb and base64 encoded string will take 37% more and that's approximately between 500kb andd 600kb.Why Png is taking this much difference with jpg format in size??? – KJEjava48 Apr 19 '17 at 07:36
  • Just use JPEG for both. PNG is lossless and thus bigger for big data. – tynn Apr 19 '17 at 07:41
  • Does using image quality as 80,100 in each case leads any size difference?? – KJEjava48 Apr 19 '17 at 07:44
  • 1
    You can easily find that out yourself. Just test it. – greenapps Apr 19 '17 at 08:13