Hough线变换的实现

我在努力实现 Hough Line Transform .

输入。

期望的行为。 我的源代码将生成以下输出,因为它是由 sample application

在这里,我们可以看到:

1. 输出的尺寸与输入图像相同。
2. 正弦波的交点几乎出现在中心。
3. 波的交叉模式非常小和简单。

我的源代码生成的输出与AForge生成的输出不同。

• 十字路口不在中间。
• 波形也不同。

为什么我的代码会产生不同的输出?

.

源代码

我自己写了下面的代码。以下是 a Minimal, Complete, and Verifiable 源代码。

public class HoughMap
{
    public int[,] houghMap { get; private set; }
    public int[,] image { get; set; }

    public void Compute()
    {
        if (image != null)
        {
            // get source image size
            int inWidth = image.GetLength(0);
            int inHeight = image.GetLength(1);

            int inWidthHalf = inWidth / 2;
            int inHeightHalf = inHeight / 2;

            int outWidth = (int)Math.Sqrt(inWidth * inWidth + inHeight * inHeight);
            int outHeight = 180;
            int outHeightHalf = outHeight / 2;

            houghMap = new int[outWidth, outHeight];

            // scanning through each (x,y) pixel of the image--+
            for (int y = 0; y < inHeight; y++)               //|
            {                                                //|
                for (int x = 0; x < inWidth; x++)//<-----------+
                {
                    if (image[x, y] != 0)//if a pixel is black, skip it.
                    {
                        // We are drawing some Sine waves. So, it may 
                        // vary from -90 to +90 degrees.
                        for (int theta = -outHeightHalf; theta < outHeightHalf; theta++)
                        {
                            double rad = theta * Math.PI / 180;
                            // respective radius value is computed
                            //int radius = (int)Math.Round(Math.Cos(rad) * (x - inWidthHalf) - Math.Sin(rad) * (y - inHeightHalf));
                            //int radius = (int)Math.Round(Math.Cos(rad) * (x + inWidthHalf) - Math.Sin(rad) * (y + inHeightHalf));
                            int radius = (int)Math.Round(Math.Cos(rad) * (x) - Math.Sin(rad) * (outHeight - y));

                            // if the radious value is between 1 and 
                            if ((radius > 0) && (radius <= outWidth))
                            {
                                houghMap[radius, theta + outHeightHalf]++;
                            }
                        }
                    }
                }
            }
        }
    }
}

public partial class Form1 : Form
{
    public Form1()
    {
        InitializeComponent();

        Bitmap bitmap = (Bitmap)pictureBox1.Image as Bitmap;

        int[,] intImage = ToInteger(bitmap);

        HoughMap houghMap = new HoughMap();
        houghMap.image = intImage;
        houghMap.Compute();

        int[,] normalized = Rescale(houghMap.houghMap);

        Bitmap hough = ToBitmap(normalized, bitmap.PixelFormat);

        pictureBox2.Image = hough;
    }

    public static int[,] Rescale(int[,] image)
    {
        int[,] imageCopy = (int[,])image.Clone();

        int Width = imageCopy.GetLength(0);
        int Height = imageCopy.GetLength(1);

        int minVal = 0;
        int maxVal = 0;

        for (int j = 0; j < Height; j++)
        {
            for (int i = 0; i < Width; i++)
            {
                double conv = imageCopy[i, j];

                minVal = (int)Math.Min(minVal, conv);
                maxVal = (int)Math.Max(maxVal, conv);
            }
        }

        int minRange = 0;
        int maxRange = 255;

        int[,] array2d = new int[Width, Height];

        for (int j = 0; j < Height; j++)
        {
            for (int i = 0; i < Width; i++)
            {
                array2d[i, j] = (maxRange - minRange) * (imageCopy[i,j] - minVal) / (maxVal - minVal) + minRange;
            }
        }

        return array2d;
    }

    public int[,] ToInteger(Bitmap input)
    {
        int Width = input.Width;
        int Height = input.Height;

        int[,] array2d = new int[Width, Height];

        for (int y = 0; y < Height; y++)
        {
            for (int x = 0; x < Width; x++)
            {
                Color cl = input.GetPixel(x, y);

                int gray = (int)Convert.ChangeType(cl.R * 0.3 + cl.G * 0.59 + cl.B * 0.11, typeof(int));

                array2d[x, y] = gray;
            }
        }

        return array2d;
    }

    public Bitmap ToBitmap(int[,] image, PixelFormat pixelFormat)
    {
        int[,] imageCopy = (int[,])image.Clone();

        int Width = imageCopy.GetLength(0);
        int Height = imageCopy.GetLength(1);

        Bitmap bitmap = new Bitmap(Width, Height, pixelFormat);

        for (int y = 0; y < Height; y++)
        {
            for (int x = 0; x < Width; x++)
            {
                int iii = imageCopy[x, y];

                Color clr = Color.FromArgb(iii, iii, iii);

                bitmap.SetPixel(x, y, clr);
            }
        }

        return bitmap;
    }
}