ConvertToBytes.java

private ByteBuffer convertBitmapToByteBuffer(Bitmap bitmap) {
    ByteBuffer byteBuffer = ByteBuffer.allocateDirect(MODEL_INPUT_SIZE);
    byteBuffer.order(ByteOrder.nativeOrder());
    int[] intValues = new int[INPUT_IMG_SIZE_WIDTH * INPUT_IMG_SIZE_HEIGHT];
    bitmap.getPixels(intValues, 0, bitmap.getWidth(), 0, 0, bitmap.getWidth(), bitmap.getHeight());
    int pixel = 0;
    for (int i = 0; i < INPUT_IMG_SIZE_WIDTH; ++i) {
        for (int j = 0; j < INPUT_IMG_SIZE_HEIGHT; ++j) {
            final int val = intValues[pixel++];
            byteBuffer.putFloat((((val >> 16) & 0xFF) - IMAGE_MEAN) / IMAGE_STD);
            byteBuffer.putFloat((((val >> 8) & 0xFF) - IMAGE_MEAN) / IMAGE_STD);
            byteBuffer.putFloat((((val) & 0xFF) - IMAGE_MEAN) / IMAGE_STD);
        }
    }
    return byteBuffer;
}