Image Quality API Response Scheme

Haut.AI provides an AI algorithm that analyzes the quality of selfie images for the consequent skin analysis. Only high-quality selfie images allow for reliable skin analysis.

Description

The algorithm analyzes the overall quality of an input image for the consequent skin analysis, which is done through an API. The algorithm returns the evaluation of quality properties and human-readable feedback with an explanation of why an image is of high or low quality.

You can select the result of this algorithm by selecting:

"algorithm_tech_name": "quality"

main_metric

The main metric is an overall score that indicates the quality of a selfie image.

"main_metric": {
    "value": 78,
    "widget_type": "bad_good_line",
    "name": "Image Quality Score",
    "tech_name": "image_quality_score",
    "widget_meta": null,
    "units": null
},

• value the image quality score ranges from [0,100]. The higher the value, the better the image quality

• "widget_type": "bad_good_line" this indicates that a higher value is better

• name metric name (may change)

• tech_name metric technical name (does not change)

• widget_meta empty, ignore

• units empty, ignore

sub_metrics

Sub-metrics are a set of features that define an image's quality. There are 2 types of sub-metrics:

• scores: sub-metrics with "tech_name" property ending with "_score"

• raw metrics: other sub-metrics

"sub_metrics": [
    < here is an example of a "score" sub-metric >
    {
        "value": 0, 
        "widget_type": 
        "bad_good_line", 
        "name": "rotation_score", 
        "tech_name": "rotation_score", 
        "widget_meta": null, 
        "units": null
    }, 
    ...
    < here is an example of "raw metrics" sub-metric >
    {
        "value": -41, 
        "widget_type": "numeric", 
        "name": "angles_yaw_angle_degree", 
        "tech_name": "angles_yaw_angle_degree", 
        "widget_meta": null, 
        "units": null
    },
    ...
]

Scores

Structure

• value the image quality score ranges from [0,100]. The higher the value, the better the image quality

• "widget_type": "bad_good_line" this indicates that a higher value is better

• name metric name (may change)

• tech_name metric technical name (does not change)

• widget_meta empty, ignore

• units empty, ignore

Meaning

tech_name	description	interpretation
full_face_score	This parameter describes the degree of face presence on image, necessary for analysis	A higher value is better. 0: at least one face skin area is not present fully on the image 100: the face is fully present on the image We suggest using 50 as a threshold to separate high- and low-quality images
rotation_score	This parameter describes the deviation of a head position from looking straight into the camera.	A higher value is better. 0 value: the head is significantly rotated (more than$45^{o}$along any or both axes) 100: the head has a perfect position with the face looking straight into the camera We suggest using 50 as a threshold to separate high- and low-quality images.
occlusion_score	This parameter describes the degree of face skin areas occlusion by a non-skin objects	A higher value is better. 0: one or several large skin areas (forehead, cheeks, chin) are not visible because of occlusion by an object or significantly high-contrast light 100: all face skin areas relevant for analysis are visible on the image We suggest using 50 as a threshold to separate high- and low-quality images
resolution_score	This parameter describes the sufficiency of resolution of a part of an image related to the detected face	A higher value is better. 0: the image resolution and/or face size in the image is too low 100: the face resolution is good enough for further image analysis We suggest using 50 as a threshold to separate high- and low-quality images
focus_score	This parameter describes the degree of image distortions similar to motion/misfocus blur that usually prevent correct small-feature extraction.	A higher value is better. 0: the image has severe distortions 100: the image has no detectable distortions or the distortions are negligible for further analysis We suggest using 50 as a threshold to separate bad and good quality images
lightness_score	This parameter describes the sufficiency of face illumination (exposition)	A higher value is better. Interpretation: 0: the face illumination is poor due to global over-exposure or under-exposure 100: the face illumination is sufficient enough for further image analysis We suggest using 50 as a threshold to separate high- and low-quality images
shadows_score	This parameter describes the degree of side illumination as a uniformness of face illumination	A higher value is better. 0: the face illumination is poor due to significant shadows caused by side illumination 100: the face illumination is uniform enough for further image analysis We suggest using 50 as a threshold to separate high- and low-quality images
colortone_score	This parameter describes the degree of color tone of the face illumination.	A higher value is better. 0: the face illumination is poor due to significantly incorrect white balance (color tone of light) 100: the face illumination is illuminated with neutral white light We suggest using 50 as a threshold to separate high- and low-quality images

Raw Metrics

Structure

• value float or int value

• "widget_type": different types, describing the exact logic of value reading. The most common are:

  • "numeric" - just a number

  • "bad_good_line" - indicates that a higher value is better

• name metric name (may change)

• tech_name metric technical name (does not change)

• widget_meta empty, ignore

• units empty, ignore

problems

problems is a list of all detected issues with image quality, returned as a short codenames. The list can contain from 0 (no problems) to N (several problems):

"problems": ["wrong_angle", "low_resolution", "misfocus_or_distortion"]

Meaning

Every codename reflect exact case, described in a table below:

codename	description
no_detection	No face detected
out_of_frame	Face is not fully visible
far_from_camera	Face is too far from camera
wrong_angle	Head is rotated at the wrong angle
skin_occlusion	Skin is partially not visible
low_resolution	Low face resolution
misfocus_or_distortion	Image is distorted or blurred
compression_artifacts	Image compression artifacts are visible
noise	Noisy image
too_dark	Image is too dark
too_bright	Image is too bright
strong_shadows	Front facing light required
colored_illumination	Incorrect white balance

⚠️ [DEPRECATED] feedback

This field will be removed in the nearest update. Use problems instead

feedback is a message with information about the image quality in form of 2 objects:

• overlay - short summary

• tooltip - more verbose list of issues, split to critical / warning / good condition

"feedback": {
        "overlay": "Low quality image",
        "tooltip": {
            "positive": [
                "Good face resolution"
            ],
            "warn": [],
            "negative": [
                "Unacceptable face illumination"
            ]
        }

• overlay is an informal message about the overall image quality. It returns an informal rating of the image quality:

  • "Good quality image" - image quality is suitable for skin analysis

  • "Low-quality image" - image quality is low for skin analysis

  • "No face detected" - face is not detected. Image can't be processed by skin assessment algorithms

  • "Not full face"- image is not fully presented in the image. Image is not suitable for skin analysis

  • "Face is rotated" - face is extremely rotated in the image. Image is not suitable for skin analysis

• tooltip is an informal message about image quality and warnings

  • positive possible feedback values are:

    • Good face resolution

    • Good face illumination

  • warn possible feedback values are:

    • Poor face resolution

    • Poor face illumination

  • negative possible feedback values are:

    • Face is not detected

    • Face is not fully presented

    • Face is rotated

    • Misfocus or distortion

    • Noisy image

    • Unacceptable face resolution

    • Unacceptable face illumination

Example (JSON)

5KB

quality.json