The following recommendations are in addition to Recommendations for facial comparison input images.
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Image Resolution – There is no minimum requirement for image resolution, as long as the face resolution is 50 x 50 pixels for images with a total resolution up to 1920 x 1080. Higher-resolution images require a larger minimum face size.
Note
The preceding recommendation is based on the native resolution of the camera. Generating a high-resolution image from a low-resolution image does not produce the results needed for face search (due to artifacts generated by the up-sampling of the image).
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Camera Angle – There are three measurements for camera angle—pitch, roll, and yaw.
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Pitch – We recommend a pitch of less than 30 degrees when the camera is facing down and less than 45 degrees when the camera is facing up.
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Roll – There isn’t a minimum requirement for this parameter. Amazon Rekognition can handle any amount of roll.
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Yaw – We recommend a yaw of less than 45 degrees in either direction.
The face angle along any axis that is captured by the camera is a combination of both the camera angle facing the scene and the angle at which the subject’s head is in the scene. For example, if the camera is 30 degrees facing down and the person has their head down a further 30 degrees, the actual face pitch as seen by the camera is 60 degrees. In this case, Amazon Rekognition would not be able to recognize the face. We recommend setting up cameras such that the camera angles are based on the assumption that people are generally looking into the camera with the overall pitch (combination of face and camera) at 30 degrees or less.
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Camera Zoom – The recommended minimum face resolution of 50 x 50 pixels should drive this camera setting. We recommend using the zoom setting of a camera so that the desired faces are at a resolution no less than 50 x 50 pixels.
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Camera Height – The recommended camera pitch should drive this parameter.
