C#原生图片模板匹配

Question

我在这里遇到了一些性能问题。我的图像处理教授让我在没有任何库的情况下进行模板匹配，所以我用 c# 做了......它做得很好，但非常非常慢在一张 500x500 的图像中找到一个 80x80 的模板，这需要几分钟的时间，而且我的 cpu

的使用率不超过 20%

我是不是做错了什么？

这是我的代码，所有图片都是灰色的。

    public Task<Point[]> MatchImage(Bitmap orig, Bitmap template, int limit = 30)
    {
        Task<Point[]> tsk = 
        new Task<Point[]>(() =>
        {
            Point p;
            List<Point> l = new List<Point>();
            int oh = orig.Height, ow = orig.Width;
            int th = template.Height, tw = template.Width;

            for (int x = 0; x < oh - th; x++)
                for (int y = 0; y < ow - tw; y++)
                {
                    p = new Point(x, y);
                    if (sumBitArea(orig, template, p) <= limit)
                        l.Add(p);
                }
                return l.ToArray();
        });

        tsk.Start();
        return tsk;
    }


    /// <summary>
    /// Soma os pixels de uma determinada imagem
    /// PS PARA USAR MANDE A IMAGEM RECORTADA !
    /// SE MANDAR INTEIRA VAI RETORNAR O VALOR TOTAL.
    /// USEM A GRAPHCS E UM RECTANGLE !
    /// </summary>
    /// <param name="image">treixo da imagem original</param>
    /// <param name="template">imagem template</param>
    /// <param name="p">ponto inicial de referencia</param>
    /// <returns>o valor da soma</returns>
    private int sumBitArea(Bitmap image, Bitmap template, Point p)
    {
        int value = 0;

        int height = p.X + template.Height;
        int width = p.Y + template.Width;

        for (int x = p.X, xt = 0; x < height; x++, xt++)
            for (int y = p.Y, yt = 0; y < width; y++,yt++)
            {
                int tmp = Math.Abs(image.GetPixel(y, x).R - template.GetPixel(yt, xt).R);
                value += tmp;
            }

        return value;
    }

解决方案 - 解决了锁定位

这里是解决代码

    public Task<Point[]> MatchImage(Bitmap orig, Bitmap template, int limit = 30)
    {
        Task<Point[]> tsk =
        new Task<Point[]>(() =>
        {
            BitmapData lockedOrig = orig.LockBits(
               new Rectangle(0, 0, orig.Width, orig.Height),
               ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb);

            //bloqueando a leitura da memoria em que a imagem nova sera colocada
            BitmapData lockedTemplate = template.LockBits(
               new Rectangle(0, 0, template.Width, template.Height),
               ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb);

            Point p;
            List<Point> l = new List<Point>();
            int oh = orig.Height, ow = orig.Width;
            int th = template.Height, tw = template.Width;

            for (int y = 0; y < oh - th; y++)
            {
                for (int x = 0; x < ow - tw; x++)
                {
                    p = new Point(x, y);
                    if (sumBitArea(lockedOrig, lockedTemplate, p) <= limit)
                        l.Add(p);
                }
            }

            orig.UnlockBits(lockedOrig);
            template.UnlockBits(lockedTemplate);
            return l.ToArray();
        });

        tsk.Start();
        return tsk;
    }

    unsafe private int sumBitArea(BitmapData image, BitmapData template, Point p)
    {
        int value = 0;
        int pixelSize = 3;

        int height = p.Y + template.Height;
        int width = p.X + template.Width;
        int x = p.X, xt = 0;
        int y = p.Y, yt = 0;
        byte* tRow;
        byte* oRow;

        for (yt = 0 ; y < height; y++, yt++)
        {
            //criando um ponteiro para a imagem original
            oRow = (byte*)image.Scan0 + (y * image.Stride);

            //criando um ponteiro para a nova imagem
            tRow = (byte*)template.Scan0 + (yt * template.Stride);

            for (xt = 0; x < width; x++, xt++)
            {
                int tmp = Math.Abs((byte)oRow[x * pixelSize + 2] - (byte)tRow[xt * pixelSize + 2]);
                value += tmp;
            }
        }
        return value;
    }

Answer 1

您是否尝试过锁定位或使用 FastBitmap 实现？您应该能够找到大量这样的实现。它应该加速多次获取像素。您只需要妥善处理它即可。

C#原生图片模板匹配

C# native Image template match

c#

performance

image-processing

native

template-matching