How to convert Image into Byte Array in Android

Here i show code for both if your image is from GALLERY and CAMERA

if (requestCode == IMAGE_PICKER_REQUEST && resultCode == RESULT_OK) {
        fileName = getRealPathFromURI(data.getData());

        try {
             if (bitmap != null) {
                    bitmap.recycle();
                }
            InputStream stream = getContentResolver().openInputStream(
                    data.getData());

            bitmap = BitmapFactory.decodeStream(stream);
            stream.close();
            image.setImageBitmap(bitmap);
            //picNameText.setText("Selected: en"
                //  + getStringNameFromRealPath(fileName));

            ByteArrayOutputStream stream1 = new ByteArrayOutputStream();
            bitmap.compress(Bitmap.CompressFormat.PNG, 100, stream1);
            imageInByte = stream1.toByteArray();

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

    if (requestCode == IMAGE_TAKER_REQUEST && resultCode == RESULT_OK) {
        Bitmap photo = (Bitmap) data.getExtras().get("data");
        image.setImageBitmap(photo);

        ByteArrayOutputStream stream2 = new ByteArrayOutputStream();
        photo.compress(Bitmap.CompressFormat.PNG, 100, stream2);
        imageInByte = stream2.toByteArray();

    }

enjoy it work for me.....

Try following code.

int bytes = bitmap.getByteCount();
//Create a new buffer
ByteBuffer buffer = ByteBuffer.allocate(bytes); 
//Move the byte data to the buffer
b.copyPixelsToBuffer(buffer); 
byte[] array = buffer.array();

1. A 32-bit Bitmap use a int32 to save a ARGB color, and we can use a int array to represent a bitmap. Using Bitmap.getPixels() and Bitmap.setPixels() to convert a Bitmap to int array and vise verse. And a int array can be easily convert to byte array.
2. @Chintan Rathod also show a good solution by using Bitmap.copyPixelsToBuffer(), nearly the same with the first one.
3. Since your goal is to upload the bitmap to server, send a compressed file is the best solution. Your code is just doing the right thing. You said that you are getting negative values in byte array, which is not an error. Just upload the byte array to server and save it as a jpeg file.

A 32-bit Bitmap use a int32 to save a ARGB color, and we can use a int array to represent a bitmap. Using Bitmap.getPixels() and Bitmap.setPixels() to convert a Bitmap to int array and vise verse. And a int array can be easily convert to byte array.