In Chapter 1, Getting Started with Microsoft Cognitive Services, we learned the very basic form of face detection. In the example, we retrieved a Face array. This contained information on all faces that were found in an image. In that specific example, we obtained information about the face rectangle, face ID, face landmarks, and age.

When calling the API, there are four request parameters, as shown in the following table:

        

      
              
Parameter           Description
            
              
image
           
              

    
              
return FaceId (optional)           Boolean value. This specifies whether the response should include the face ID or not.
    
              
return FaceLandmarks (optional)           Boolean value. This specifies whether the response should include FaceLandmarks in detected faces.
    
              
return FaceAttributes (optional)
           
              

If a face is successfully discovered, it will expire in 24 hours. When calling other parts of the Face API, you are often required to have a face ID as an input. In those cases, we need to detect a face first, followed by the call to the API we wish to use, using the detected face as a parameter.

Using this knowledge, I challenge you to play around with the example in Chapter 1, Getting Started with Microsoft Cognitive Services. Draw a rectangle around the face. Mark the eyes in the image.