Kairos enroll API returns confidence in the respon

I am exploring Kairos Facial Recognition APIs. The API /enroll is used for uploading an image to Kairos for a subject_id. I noticed that the response of enroll API contains a confidence score. The image is treated as a new image. What does this confidence mean? When you verify an image, in that case the confidence score is important. But while uploading an image, why does the API return a confidence?

I assume, the API compares the image to the images uploaded before for that subject_id and returns the confidence. Is this the case or is it something else?

API Documentation: API_docs.

Here is a sample response for reference:

{
    "face_id": "f2f0f8de43e545f8aff",
    "images": [
        {
            "attributes": {
                "age": 40,
                "asian": 0.13225,
                "black": 0.00103,
                "gender": {
                    "femaleConfidence": 0.00028,
                    "maleConfidence": 0.99972,
                    "type": "M"
                },
                "glasses": "None",
                "hispanic": 0.09578,
                "lips": "Together",
                "other": 0.27899,
                "white": 0.49195
            },
            "transaction": {
                "confidence": 0.99932,
                "eyeDistance": 30,
                "face_id": "f2f0f8de43e545f8aff",
                "gallery_name": "ps-recognize",
                "height": 70,
                "image_id": 1,
                "pitch": -14,
                "quality": 0.10107,
                "roll": -4,
                "status": "success",
                "subject_id": "vinod-khanna.&**@~`%$#_=+/",
                "timestamp": "1526029231708",
                "topLeftX": 124,
                "topLeftY": 42,
                "width": 70,
                "yaw": 1
            }
        }
    ]
}

Yes, this isn't clear from the documentation.

For /recognize and /verify the confidence % represents how similar the face sent in with the request is to the the face being compared against.

For /detect and /enroll the confidence represents how confident the engine is that it found a face. Usually you will see 98-99 percent range for those values.

Disclosure: Kairos.com CTO