Android Bitmap to Base64 String

Question

How do I convert a large Bitmap  photo taken with the phone s camera  to a Base64 String

User · Answer

All of these answers are inefficient as they needlessly decode to a bitmap and then recompress the bitmap. When you take a photo on Android, it is stored as a jpeg in the temp file you specify when you follow the android docs.

What you should do is directly convert that file to a Base64 string. Here is how to do that in easy copy-paste (in Kotlin). Note you must close the base64FilterStream to truly flush its internal buffer.

fun convertImageFileToBase64(imageFile: File): String {

    return FileInputStream(imageFile).use { inputStream ->
        ByteArrayOutputStream().use { outputStream ->
            Base64OutputStream(outputStream, Base64.DEFAULT).use { base64FilterStream ->
                inputStream.copyTo(base64FilterStream)
                base64FilterStream.close()
                outputStream.toString()
            }
        }
    }
}

As a bonus, your image quality should be slightly improved, due to bypassing the re-compressing.

User · Answer

Now that most people use Kotlin instead of Java  here is the code in Kotlin for converting a bitmap into a base64 string   import java io ByteArrayOutputStream  private fun encodeImage bm  Bitmap   String            val baos   ByteArrayOutputStream           bm compress Bitmap CompressFormat JPEG  100  baos          val b   baos toByteArray           return Base64 encodeToString b  Base64 DEFAULT

User · Answer

Use this code     import android graphics Bitmap  import android graphics BitmapFactory  import android util Base64  import java io ByteArrayOutputStream   public class ImageUtil         public static Bitmap convert String base64Str  throws IllegalArgumentException                 byte   decodedBytes   Base64 decode  base64Str substring base64Str indexOf        1   Base64 DEFAULT            return BitmapFactory decodeByteArray decodedBytes  0  decodedBytes length               public static String convert Bitmap bitmap                  ByteArrayOutputStream outputStream   new ByteArrayOutputStream            bitmap compress Bitmap CompressFormat PNG  100  outputStream           return Base64 encodeToString outputStream toByteArray    Base64 DEFAULT

User · Answer

The problem with jeet s answer is that you load all bytes of the image into a byte array  which will likely crash the app in low-end devices  Instead  I would first write the image to a file and read it using Apache s Base64InputStream class  Then you can create the Base64 string directly from the InputStream of that file  It will look like this     Don t forget the manifest permission to write files final FileOutputStream fos   new FileOutputStream yourFileHere    bitmap compress Bitmap CompressFormat PNG  100  fos    fos close     final InputStream is   new Base64InputStream  new FileInputStream yourFileHere        Now that we have the InputStream  we can read it and put it into the String final StringWriter writer   new StringWriter    IOUtils copy is   writer  encoding   final String yourBase64String   writer toString      As you can see  the above solution works directly with streams instead  avoiding the need to load all the bytes into a variable  therefore making the memory footprint much lower and less likely to crash in low-end devices  There is still the problem that putting the Base64 string itself into a String variable is not a good idea  because  again  it might cause OutOfMemory errors  But at least we have cut the memory consumption by half by eliminating the byte array   If you want to skip the write-to-a-file step  you have to convert the OutputStream to an InputStream  which is not so straightforward to do  you must use PipedInputStream but that is a little more complex as the two streams must always be in different threads

User · Answer

Try this  first scale your image to required width and height  just pass your original bitmap  required width and required height to the following method and get scaled bitmap in return    For example  Bitmap scaledBitmap   getScaledBitmap originalBitmap  250  350    private Bitmap getScaledBitmap Bitmap b  int reqWidth  int reqHeight        int bWidth   b getWidth        int bHeight   b getHeight         int nWidth   bWidth      int nHeight   bHeight       if nWidth  gt  reqWidth                int ratio   bWidth   reqWidth          if ratio  gt  0                        nWidth   reqWidth              nHeight   bHeight   ratio                       if nHeight  gt  reqHeight                int ratio   bHeight   reqHeight          if ratio  gt  0                        nHeight   reqHeight              nWidth   bWidth   ratio                       return Bitmap createScaledBitmap b  nWidth  nHeight  true       Now just pass your scaled bitmap to the following method and get base64 string in return   For example  String base64String   getBase64String scaledBitmap    private String getBase64String Bitmap bitmap        ByteArrayOutputStream baos   new ByteArrayOutputStream         bitmap compress Bitmap CompressFormat JPEG  100  baos        byte   imageBytes   baos toByteArray         String base64String   Base64 encodeToString imageBytes  Base64 NO WRAP        return base64String      To decode the base64 string back to bitmap image   byte   decodedByteArray   Base64 decode base64String  Base64 NO WRAP   Bitmap decodedBitmap   BitmapFactory decodeByteArray decodedByteArray  0  decodedString length

User · Answer

I have fast solution  Just create a file ImageUtil java  import android graphics Bitmap  import android graphics BitmapFactory  import android util Base64  import java io ByteArrayOutputStream   public class ImageUtil       public static Bitmap convert String base64Str  throws IllegalArgumentException               byte   decodedBytes   Base64 decode              base64Str substring base64Str indexOf         1               Base64 DEFAULT                     return BitmapFactory decodeByteArray decodedBytes  0  decodedBytes length              public static String convert Bitmap bitmap                ByteArrayOutputStream outputStream   new ByteArrayOutputStream            bitmap compress Bitmap CompressFormat PNG  100  outputStream            return Base64 encodeToString outputStream toByteArray    Base64 DEFAULT              Usage   Bitmap bitmap   ImageUtil convert base64String     or  String base64String   ImageUtil convert bitmap

User · Answer

use following method to convert bitmap to byte array   ByteArrayOutputStream byteArrayOutputStream   new ByteArrayOutputStream      bitmap compress Bitmap CompressFormat PNG  100  byteArrayOutputStream   byte   byteArray   byteArrayOutputStream  toByteArray      to encode base64 from byte array use following method  String encoded   Base64 encodeToString byteArray  Base64 DEFAULT

[android] Android Bitmap to Base64 String

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