How to evaluate the quality of a face biometry? – BioPassID

To make a face image standardization check, the check_icao method is used, which evaluates if the face photo quality matches the ISO/IEC 19794-5, ICAO norm. This standard was created to allow machines to make face images analysis automatically with more efficiency, thus, verifying that the photo being sent to the system complies with this standard will enhance your usage of BioPass ID.

For the request body, insert a text in JSON format containing the base64 string of the image you want to check. An example can be seen below:

{
  "Check": {
    "Image": "/9j/4AAQSkZJRgABAQAAAQABAAD/2wCEAAY"
  }
}

For the header, insert the content type and your subscription key, replacing <API-KEY>, as in the example below:

{
  'Content-Type': 'application/json',
  'Ocp-Apim-Subscription-Key': '<API-KEY>'
}

In the request, the specification that it’s a POST method, the https://api.biopassid.com/quality/check_icao URL, the header, and the body must be passed as in the examples given. See below how this request would be, written in Python, but that can be check in several other programming languages in our documentation:

import http.client
import json

conn = http.client.HTTPSConnection("hml-api.biopassid.com")
payload = json.dumps({
  "Check": {
    "Image": "/9j/4AAQSkZJRgABAQAAAQABAAD/2wCEAAY"
  }
})
headers = {
  'Content-Type': 'application/json',
  'Ocp-Apim-Subscription-Key': '52ac87259c6e46e78525cb47e469c4ce'
}
conn.request("POST", "/quality/check_icao", payload, headers)
res = conn.getresponse()
data = res.read()
print(data.decode("utf-8")

In case you receive the message 200 (OK) in your response, this means the request was completed successfully. The content of the response will be an ICAO object containing details about the result of the examination.

Firstly, it will have a variable FaceImageConformed, that has a numeric value referring to the face position in the picture. The meaning of each number can be seen in the table below:

Code	Description
-1	Error in image processing
0	No problem was found
1	Face not detected
2	No landmark identified
3	Face shifted to the left
4	Face shifted to the right
5	Face shifted up
6	Face shifted down
7	Face is too far

Next, the variable IsAllConformed will contain a Boolean value indicating if the photo completely meets all the requirements imposed by the ICAO standard.

Lastly, there will be a Requirements object, that shows for each requirement if it was met (through the Boolean variable IsConformed) and its assurance level (from 0 to 100, through the variable Confidence). A table showing each requirement and what it means can be seen below:

Requirement	Description
Blurred	The photo must not be blurred
LookingAway	The individual must be staring directly at the camera
InkMarked	The photo must not have ink marks
UnnaturalSkin	The photo must show the individual's natural skin tone
TooDarkLight	The photo must have adequate brightness
WashedOut	The photo must have adequate contrast level
Pixelation	The photo must not be pixelated
HairAcrossEyes	The eyes must not be blocked by the individual’s hair
EyesClosed	Eyes must be opened
VariedBackground	The photo must be taken with a uniform background
Roll_Pitch_Yaw	Head must be faced to the camera and in frontal position
FlashReflectionOnSkin	The picture must not show flash reflections on the skin
RedEyes	The picture must not show red eyes
ShadowsBehindHead	The picture must not have shadows behind the individual
ShadowsAcrossFace	The picture must not have shadows in the face
DarkTintedLenses	The individual cannot be wearing sunglasses
FlashReflectionOnLenses	The picture must not show reflections in the individual’s glasses lens
FramesTooHeavy	Heavy-set glasses must not be worn
FramesCoveringEyes	The frame of the individual's glasses cannot cover his eyes
Hat_Cap	The individual cannot wear a hat or cap in the picture
VeilOverFace	If wearing a veil, it cannot cover the face
MouthOpen	Mouth must be closed
OtherFaces	The individual must be alone in the picture

Lastly, an example showing the system response for the request made previously can be seen below:

{
    "ICAO": {
        "FaceImageConformed": 0,
        "IsAllConformed": false,
        "Requirements": {
            "Blurred": {
                "IsConformed": true,
            },
            "LookingAway": {
                "IsConformed": true,
            },
            "InkMarked": {
                "IsConformed": true,
            },
            "UnnaturalSkin": {
                "IsConformed": true,
            },
            "TooDarkLight": {
                "IsConformed": false,
            },
            "WashedOut": {
                "IsConformed": true,
            },
            "Pixelation": {
                "IsConformed": true,
            },
            "HairAcrossEyes": {
                "IsConformed": true,
            },
            "EyesClosed": {
                "IsConformed": true,
            },
            "VariedBackground": {
                "IsConformed": true,
            },
            "Roll_Pitch_Yaw": {
                "IsConformed": false,
            },
            "FlashReflectionOnSkin": {
                "IsConformed": true,
            },
            "RedEyes": {
                "IsConformed": true,
            },
            "ShadowsBehindHead": {
                "IsConformed": true,
            },
            "ShadowsAcrossFace": {
                "IsConformed": true,
            },
            "DarkTintedLenses": {
                "IsConformed": true,
            },
            "FlashReflectionOnLenses": {
                "IsConformed": true,
            },
            "FramesTooHeavy": {
                "IsConformed": true,
            },
            "FramesCoveringEyes": {
                "IsConformed": false,
            },
            "Hat_Cap": {
                "IsConformed": true,
            },
            "VeilOverFace": {
                "IsConformed": true,
            },
            "MouthOpen": {
                "IsConformed": true,
            },
            "OtherFaces": {
                "IsConformed": true,
            }
        }
    }
}

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