AIParkingApplication/AIParkingApplication/PlateDetector.cs

using OpenCvSharp;
using System;
using System.Linq;

namespace AIParkingApplication
{
    public class PlateDetector
    {
        private PlateType plateType;
        private Size minSizePlate;
        private Size maxSizePlate;
        private double scaleFactor;
        private int minNeighbors;
        private CascadeClassifier plateCascadeClassifier;

        public PlateDetector(PlateType plateType, Size minSizePlate, Size maxSizePlate, double scaleFactor, int minNeighbors)
        {
            this.plateType = plateType;
            this.minSizePlate = minSizePlate;
            this.maxSizePlate = maxSizePlate;
            this.scaleFactor = scaleFactor;
            this.minNeighbors = minNeighbors;
            plateCascadeClassifier = new CascadeClassifier(this.plateType == PlateType.Square ? PlateDetectorConstant.SQUARE_PLATE_WEIGHT_FILENAME : PlateDetectorConstant.LONG_PLATE_WEIGHT_FILENAME);
        }

        public Mat DetectPlate(Mat frame)
        {
            Rect[] plateRectsDetected = plateCascadeClassifier.DetectMultiScale(frame, scaleFactor, minNeighbors, HaarDetectionType.ScaleImage, minSizePlate, maxSizePlate);
            Console.WriteLine("Plate Detected Length: " + plateRectsDetected.Length);
            if (plateRectsDetected.Length > 0)
            {
                Mat plateImage = GetBiggestPlate(plateRectsDetected, frame);
                return plateImage;
            }
            else
            {
                return frame;
            }
        }

        private Rect ExtendPlateRect(Rect plateRect, int extendWidth = 50, int extendHeigh = 50)    //TODO: 50 for plate square.
        {
            int newX = plateRect.X - extendWidth;
            int newY = plateRect.Y - extendHeigh;
            int newWidth = plateRect.Width + extendWidth * 2;
            int newHeigh = plateRect.Height + extendHeigh * 2;
            return new Rect(newX, newY, newWidth, newHeigh);
        }

        private Mat GetBiggestPlate(Rect[] plateRects, Mat frame)
        {
            Rect biggestPlateRect = plateRects.OrderByDescending(x => x.Width).FirstOrDefault();
            Console.WriteLine("===================================================");
            for (int i = 0; i < plateRects.Length; i++)
            {
                Console.WriteLine($"{i}\t{plateRects[i].Width}\t{plateRects[i].Height}");
            }
            Console.WriteLine($"GetBiggestPlate - Width: {biggestPlateRect.Width}\tHeight: {biggestPlateRect.Height}");
            Rect extendedRect = ExtendPlateRect(biggestPlateRect);
            //TODO: check oversize frame
            Mat plateImage;
            try
            {
                plateImage = frame[extendedRect];
            }
            catch (Exception ex)
            {
                plateImage = frame[biggestPlateRect];
                Console.WriteLine($"Error While Extending Plate Rect: {ex.Message}");
            }
            return plateImage;
        }
    }

    public enum PlateType
    {
        Square,
        Long
    }

    public static class PlateDetectorConstant
    {
        public const string SQUARE_PLATE_WEIGHT_FILENAME = "plate.xml";
        public const string LONG_PLATE_WEIGHT_FILENAME = "plateLong.xml";

        public const double SCALE_FACTOR_DEFAULT_SQUARE_PLATE = 1.03;
        public static int MIN_NEIGHBORS_DEFAULT_SQUARE_PLATE = 2;
        public static Size MIN_SIZE_DEFAULT_SQUARE_PLATE = new Size(105, 100);
        public static Size MAX_SIZE_DEFAULT_SQUARE_PLATE = new Size(450, 400);

        public static double SCALE_FACTOR_DEFAULT_LONG_PLATE = 1.5;
        public static int MIN_NEIGHBORS_DEFAULT_LONG_PLATE = 5;
        public static Size MIN_SIZE_DEFAULT_LONG_PLATE = new Size(120, 40);
        public static Size MAX_SIZE_DEFAULT_LONG_PLATE = new Size(660, 220);
    }
}