title: MLMultiArray from UIImage for sklearn
body: <p>I just trained a sklearn model and converted it into CoreML. The problem is, I am using an image as the input to this model. However, what the model is asking for is a <code>MultiArray</code> (which is <code>MLMultiArray</code>). From <a href="https://stackoverflow.com/questions/44529869/converting-uiimage-to-mlmultiarray-for-keras-model">this question</a> I can see that there is a parameter for <code>coremltools</code> that can let you specify that the input is an image. But that parameter is for converting a Keras model, and in <code>sklearn</code> converting tool this option doesn't exist.</p>
  
  <p>The question is, how do I convert my UIImage to the MLMultiArray required by the model. (or even better, how can I enable image for the model)</p>