Base64 encoding and decoding apache commons

I am note sure what is wrong with the below code. I am trying to encode an JPG file with base64 encoding. After encoding i am checking is it base64 encoded, it returns false. I am unable to find what is that I am missing.

    public String  encodeBinary64(String value){
     String output = null;
     System.out.println("encoding the binary length "+value.length());

    byte[] byteArray = Base64.encodeBase64(value.getBytes());
         output = Arrays.toString(byteArray);

          System.out.println("output length encoding"+output.length());
          Boolean base64Encoded = Base64.isBase64(output); -- returning FALSE

          System.out.println("Base 64 Encoded "+ base64Encoded );


     return output;

 }

Update 2

The solution suggested below helped. However after decoding the base64 encoded image, when i try to open I am getting windows Photo Viewer Can't Open message. Below is the code.

         public String  decodeBinary64(String value){
     String output = null;
     System.out.println("Decoding the binary length "+value.length());

      Boolean base64Encoded = Base64.isBase64(value);
       System.out.println("base64Encoded "+base64Encoded);
      if(base64Encoded){
          byte[] byteArray = Base64.decodeBase64(value.getBytes());
        try {
            output =   new String(byteArray, "UTF-8");
        } catch (UnsupportedEncodingException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }

          System.out.println("output length "+output.length());
      }


     return output;

 }

Note:

I have verified the length of the file before encoding and after decoding. The size remains the same. But the file is unable to open.