Using openCvSharp to locate barcodes

gistfile1.txt

// optimized to find a vertical barcode in an image
// inspired by http://www.pyimagesearch.com/2014/11/24/detecting-barcodes-images-python-opencv/

using System;
using System.Drawing;
using System.Windows.Forms;
using OpenCvSharp;
using OpenCvSharp.Extensions;

namespace LocateBarcode
{
    internal class Program
    {
        private static int _displayPosition = 0;
        private const int _displayWidth = 400;

        private static void Main(string[] args)
        {
            var imagePath = args[0];
            using (var ipl = new IplImage(imagePath, LoadMode.Color))
            {

                var gray = new IplImage(ipl.Size, BitDepth.U8, 1);
                Cv.CvtColor(ipl, gray, ColorConversion.BgrToGray);

                var gradX = new IplImage(ipl.Size, BitDepth.U8, 1);
                Cv.Sobel(gray, gradX, 1, 0, ApertureSize.Scharr);
                var gradY = new IplImage(ipl.Size, BitDepth.U8, 1);
                Cv.Sobel(gray, gradY, 0, 1, ApertureSize.Scharr);

                var gradient = new IplImage(ipl.Size, BitDepth.U8, 1);
                Cv.Sub(gradY, gradX, gradient);
                Cv.ConvertScaleAbs(gradient, gradient);

                var blurred = new IplImage(ipl.Size, BitDepth.U8, 1);
                Cv.Smooth(gradient, blurred, SmoothType.Blur, 9, 9);

                var thresh = new IplImage(ipl.Size, BitDepth.U8, 1);
                Cv.Threshold(blurred, thresh, 80, 255, ThresholdType.Binary);
                ShowBitmap(thresh.ToBitmap());

                var kernel = Cv.CreateStructuringElementEx(7, 30, 3, 15, ElementShape.Rect);
                var closed = new IplImage(ipl.Size, BitDepth.U8, 1);
                var temp = new IplImage(ipl.Size, BitDepth.U8, 1);
                Cv.MorphologyEx(thresh, closed, temp, kernel, MorphologyOperation.Close);
                ShowBitmap(closed.ToBitmap());

                Cv.Erode(closed, closed, null, 4);
                Cv.Dilate(closed, closed, null, 4);

                CvSeq<CvPoint> firstContour;
                var storage = new CvMemStorage();
                var n = Cv.FindContours(closed, storage, out firstContour, CvContour.SizeOf, ContourRetrieval.External,
                                        ContourChain.ApproxSimple, Cv.Point(0, 0));

                var currentContour = firstContour;
                var biggestContour = firstContour;
                for (var i = 1; i < n; i++)
                {
                    currentContour = currentContour.HNext;
                    if (currentContour.ContourArea() < biggestContour.ContourArea())
                    {
                        biggestContour = currentContour;
                    }
                }


                var cvRect = Cv.MinAreaRect2(biggestContour, storage);
                CvPoint2D32f[] box;
                Cv.BoxPoints(cvRect, out box);

                var origHeight = Math.Abs(box[2].Y - box[0].Y);
                var padding = origHeight*0.05F;
                var x = (int) Math.Min(box[0].X, box[2].X);
                var y = (int) (Math.Min(box[0].Y, box[2].Y) - padding);
                var width = (int) Math.Abs(box[0].X - box[2].X);
                var height = (int) (Math.Abs(box[0].Y - box[2].Y) + padding*2);
                var roi = new CvRect(x, y, width, height);

                Cv.SetImageROI(ipl, roi);
                var barcode = ipl.ToBitmap();

                Cv.ResetImageROI(ipl);
                Cv.DrawRect(ipl, roi, CvColor.Green, 5);
                var taggedOrig = ipl.ToBitmap();

                ShowBitmap(taggedOrig);
                ShowBitmap(barcode);

                Application.Run();

            }

        }

        private static void ShowBitmap(Bitmap bitmap)
        {
            var bmp = new Bitmap(bitmap);
            var form = new Form
                {
                    Text = "Display IplImage in PictureBox",
                    ClientSize = new Size(_displayWidth, 700),
                    StartPosition = FormStartPosition.Manual,
                    Location = new Point(_displayPosition, 0)
                };
            _displayPosition += _displayWidth;

            var pictureBox = new PictureBox
                {
                    Dock = DockStyle.Fill,
                    SizeMode = PictureBoxSizeMode.Zoom,
                    Image = bmp,
                };
            form.Controls.Add(pictureBox);
            form.Show();
        }
    }
}