First of all check your string
http://codebeautify.org/base64-to-image-converter
Try this way to convert.
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
ImageView image =(ImageView)findViewById(R.id.image);
//encode image to base64 string
ByteArrayOutputStream baos = new ByteArrayOutputStream();
Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.logo);
bitmap.compress(Bitmap.CompressFormat.JPEG, 100, baos);
byte[] imageBytes = baos.toByteArray();
String imageString = Base64.encodeToString(imageBytes, Base64.DEFAULT);
//decode base64 string to image
imageBytes = Base64.decode(imageString, Base64.DEFAULT);
Bitmap decodedImage = BitmapFactory.decodeByteArray(imageBytes, 0, imageBytes.length);
image.setImageBitmap(decodedImage);
}
}
http://www.thecrazyprogrammer.com/2016/10/android-convert-image-base64-string-base64-string-image.html