Android : Android Face Recognition

I have this android face recognition algorithm i wrote but the problem with this is it gives me different facial values (e.g eye distance, confidence, mid-point x and y) for different pictures with the same person. for example if i have a picture of me but taken and two distinct different time and moods it gives me different face values. How can i correct that

public class FaceAlgorithm {

/**
 * Face details variables
 */
private int facesFound = 0;
private static final PointF midPoint = new PointF();
private static float eyeDistance = 0.0f;
private static float confidence = 0.0f;
/**
 * Image variables
 */
private Bitmap cameraBitmap = null;
private Bitmap output = null;

/**
 * Collector variable
 */
private ArrayList<Map<String, Float>> Faces = null;
private Map<String, Float> facevalue;

public FaceAlgorithm() {
    // TODO Auto-generated constructor stu
}

public void detectFaces() {
    if (null != cameraBitmap) {
        int width = cameraBitmap.getWidth();
        int height = cameraBitmap.getHeight();

        FaceDetector detector = new FaceDetector(width, height,
                config.MAX_FACES);
        Face[] faces = new Face[config.MAX_FACES];

        Bitmap bitmap565 = Bitmap.createBitmap(width, height,
                Config.RGB_565);
        Paint ditherPaint = new Paint();
        Paint drawPaint = new Paint();

        ditherPaint.setDither(true);
        drawPaint.setColor(Color.GREEN);
        drawPaint.setStyle(Paint.Style.STROKE);
        drawPaint.setStrokeWidth(90);

        Canvas canvas = new Canvas();
        canvas.setBitmap(bitmap565);
        canvas.drawBitmap(cameraBitmap, 0, 0, ditherPaint);

        facesFound = detector.findFaces(bitmap565, faces);

        Log.i("FaceDetector", "Number of faces found: " + facesFound);

         Faces = new ArrayList<Map<String, Float>>();

        if (facesFound > 0) {
            for (int index = 0; index < facesFound; ++index) {
                faces[index].getMidPoint(midPoint);
                eyeDistance = faces[index].eyesDistance();
                confidence = faces[index].confidence();

                Log.i("FaceDetector", "Confidence: " + confidence
                        + ", Eye distance: " + eyeDistance
                        + ", Mid Point: (" + midPoint.x + ", " + midPoint.y
                        + ")");
                facevalue = new HashMap<String, Float>();
                facevalue.put(config.TAG_CON, confidence);
                facevalue.put(config.TAG_EYE, eyeDistance);
                facevalue.put(config.TAG_MX, midPoint.x);
                facevalue.put(config.TAG_MY, midPoint.y);

                Faces.add(facevalue);
                // draws the rectangle over individual faces
                canvas.drawRect((int) midPoint.x - eyeDistance,
                        (int) midPoint.y - eyeDistance, (int) midPoint.x
                                + eyeDistance, (int) midPoint.y
                                + eyeDistance, drawPaint);                  

            }
        }else
        {
            setOutput(null);
            return;//break outta
        }

        //setting the output
        setOutput(bitmap565);
    }
}

private void setOutput(Bitmap bitmap565) {
    // TODO Auto-generated method stub
    this.output = bitmap565;
}

public Bitmap getOutput() {
    return this.output;
}

public void setCameraBitmap(Bitmap cameraBitmap) {
    this.cameraBitmap = cameraBitmap;
}

public int getNumberofFaces() {
    return this.facesFound;
}

public ArrayList<Map<String, Float>> getFacesDetected()
{
    return this.Faces;
}
}