Define minimum face quality at least 1000 for the CPU detection(fast, balanced, or accurate mode) If GPU detection used(accurate server mode) use at least 9990. Restric min and max eye distance to the expectable face sizes in the scene and/or define region of interrest. Please refer to "Innovatrics SmartFace 3.1 - Product Manual.pdf" parts "Video processing -> Mask image" and "Image processing -> Face detection".