title: How to sent image in 'application/octet-stream' content type to Azure Cognitive Services in flutter
body: <p>Hi I'am trying to sent a local image using application/octet-stream' content type to Azure Cognitive Services from flutter.
  I have follow the following but it seem to be missing the example. The only example is for 'application/json'</p>
  <pre><code>Future getAnalisis() async {
      final uri =
          &quot;https://****.cognitiveservices.azure.com/vision/v3.1/analyze?visualFeatures=Categories,Description&amp;details=Landmarks&quot;;
      final respon = await http.post(
        uri,
        body: _file,
        headers: {
          'Ocp-Apim-Subscription-Key': '*****',
          'Content-Type': 'application/octet-stream'
        },
      );
      _imageVision = serializers.deserializeWith(
          ImageVision.serializer, jsonDecode(respon.body));
      notifyListeners();
    }
  </code></pre>
  <p>and the <code>_file</code> is from</p>
  <pre><code>final pickedFile = await picker.getImage(source: ImageSource.camera);
  if (pickedFile != null) _file = File(pickedFile.path);
  </code></pre>
  <p>I also have tried the following but it of course error</p>
  <pre><code>   body: jsonDecode({'url' : _file.path}),
        headers: {
          'Ocp-Apim-Subscription-Key': '*****',
          'Content-Type': 'application/json'
        },
  </code></pre>
  <p>and currently my error message is</p>
  <pre><code> Invalid request body &quot;File:
  '/storage/emulated/0/Android/data/com.example.testRun/files/Pictures/7702e794-3a57-4a3a-a271-fd7c0964544d
  4388330820207050041.jpg'&quot;.
  </code></pre>