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Face Image Quality Characteristics

For the detailed Face Image Quality Assessment feature description, refer to Face SDK OpenAPI documentation, the processParam.quality field.

To try out the feature and view example requests and responses, navigate to the Regula Face SDK Web API demo and select the Face image quality tab.

Face image quality is evaluated based on characteristics set in processParam.quality.config, with results provided in results.detections.quality.details.

The characteristics are grouped as described below. Assessment results for each group of characteristics are provided in results.detections.quality.detailsGroups.

Image characteristics

Name Description Recommended range ICAO standard
ImageWidth The image width, pixels. Not defined 1200 px
ImageHeight The image height, pixels. Not defined 1600 px
ImageWidthToHeight The image width to height proportion. Not defined 0.74, 0.8
ImageChannelsNumber The image RGB channels number. Not defined 3
ArtFace Whether the face in the image is a photo, not a drawing, sculpture, cartoon, etc. If the returned value is out of the recommended range, the image is not a photo. 0, 0.5 Not regulated by the standard
PaddingRatio The percentage of the area of the image that was "padded" during alignment. The characteristic is needed to determine if the head goes beyond the image.

If no alignment is performed, returns 0.		 Not defined Not regulated by the standard

Head size and position

Name Description Recommended range ICAO standard
FaceMidPointHorizontalPosition The position of the "middle point" (the middle of the line connecting the eye centers) relative to the width of the image. 0.45, 0.55 Should be in a certain place so that alignment could be performed and the face placed correctly.
FaceMidPointVerticalPosition The position of the "middle point" (the middle of the line connecting the eye centers) relative to the height of the image. 0.45, 0.55 Should be in a certain place so that alignment could be performed and the face placed correctly.
HeadWidthRatio The head width to the image width ratio. 0.5, 0.75 0.5, 0.75
HeadHeightRatio The head height to the image height ratio. 0.6, 0.9 0.6, 0.9
EyesDistance Inter-eye distance — the length of the line connecting the eye centers of the left and right eye, pixels. 240 240
Yaw The yaw of the head, degrees. -5,5 -5,5
Pitch The pitch of the head, degrees. -5,5 -5,5
Roll The roll of the head, degrees. -5,5 -5,5

Face image quality

Name Description Recommended range ICAO standard
BlurLevel The blur level. 0, 0.5 The image should not be blurry.
NoiseLevel The noise level. 0, 0.5 The image should not contain noise.
UnnaturalSkinTone The true-color representation of the skin color. 0, 0.5 All images should be captured in color. Newly designed enrolment should capture color images only. The captured portrait should be a true-color representation of the holder in a typical color space.
FaceDynamicRange The range of tonal difference between the lightest light and darkest dark of an image, bits. 7,8 The dynamic range should have at least 50% of intensity variation in the facial region of the image.

Eyes characteristics

Name Description Recommended range ICAO standard
EyeRightClosed Whether the right eye is closed. 0, 0.5 Eyes should be open.
EyeLeftClosed Whether the left eye is closed. 0, 0.5 Eyes should be open.
EyeRightOccluded Whether the right eye is occluded. 0, 0.5 Eyes should not be occluded.
EyeLeftOccluded Whether the left eye is occluded. 0, 0.5 Eyes should not be occluded.
EyesRed Whether there is the red-eye effect. 0, 0.5 There should be no red-eye effect.
EyeRightCoveredWithHair Whether the right eye is covered with hair. 0, 0.5 Covering eyes with hair is prohibited.
EyeLeftCoveredWithHair Whether the left eye is covered with hair. 0, 0.5 Covering eyes with hair is prohibited.
OffGaze Whether the person is not looking directly at the camera. 0, 0.5 The person should be looking directly at the camera.

Shadows and lightning

Name Description Recommended range ICAO standard
TooDark Whether the photo is too dark. 0, 0.38 Low-light photos are prohibited.
TooLight Whether the photo is overexposed. 0, 0.5 Overexposed photos are prohibited.
FaceGlare Whether there is glare on the face. 0, 0.01 Glare on the face is not allowed.
ShadowsOnFace Whether there are shadows on the face. 0, 0.5 The face should be evenly lit.

Pose and expression

Name Description Recommended range ICAO standard
ShouldersPose Checks the symmetry of the shoulders, returns 1 for absolutely symmetrical shoulders. 0.6, 1 Shoulders should be symmetrical.
ExpressionLevel Checks the presence of any emotional facial expression. 0, 0.84 Any facial expressions are prohibited, raised eyebrows are prohibited.
MouthOpen Whether the mouth is open. 0, 0.5 The mouth should be closed.
Smile Whether the person smiles. 0, 0.5 A person should not smile.

Head occlusion

Name Description Recommended range ICAO standard
DarkGlasses Whether the person wears dark glasses. 0, 0.5 No dark glasses are allowed.
ReflectionOnGlasses Whether there are reflections on glasses.

In the current release, it always returns true. Will be developed in the coming releases.		 0, 0.5 Reflections of objects and glare on glasses are prohibited.
FramesTooHeavy Whether the glasses frames do not obscure eye details and the irises of both eyes are visible. 0, 6 Frames should not be thicker than 5% of the IED (typically 3-4 mm).
FaceOccluded Whether the face is visible and not occluded. 0, 0.5 The face should be totally visible and not occluded or covered.
HeadCovering Whether there is any head coverage other than religious headwear. 0, 0.5 Hats other than religious headwear are not allowed.
ForeheadCovering Whether the forehead is covered. 0, 0.5 If the forehead is covered by the hairstyle, it can’t be evaluated.
StrongMakeup Whether the makeup is too strong.

In the current release, it always returns true. Will be developed in the coming releases.		 0, 0.5 Only typical everyday makeup is allowed.
Headphones Whether the person is wearing headphones. 0, 0.5 Headphones are not allowed for passport photos.
MedicalMask Whether the person is wearing a medical mask. 0, 0.5 Medical masks are not allowed for passport photos.

Background

Name Description Recommended range ICAO standard
BackgroundUniformity Checks uniformity of the portrait background. 0.9, 1 A typical background for the scene is gray with a plain, dull flat surface. Plain light coloured backgrounds such as light blue or white may be used as long as there is sufficient distinction between the face/hair area and the background.
ShadowsOnBackground Whether there are shadows on the portrait background. 0.9, 1 Photos with shadows on the background are invalid.
OtherFaces The number of faces in the photo. 1 No more than one face in the photo is allowed.
BackgroundColorMatch Whether the background color matches the required hue (that is set in backgroundMatchColor). 0.8, 1 For some visas, the portrait background must be strictly white.