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我一直在研究获取图像,将其转换为灰度,然后根据按下的按钮进行图像处理的代码。当一个按钮被按下时(例如平均 3x3,Prewitt 5x5),它会调用一个 2D 乘法函数,该函数循环遍历灰度图像,同时循环遍历内核,将矩阵中的所有值相加。如果任何值超过 255,则将其设置为 255。然后在临时位图变量上使用 SetPixel,最终将其放入图片框中。当我运行程序时,我选择了一个图像并显示它(作为灰度),但是在选择了一个过滤器后,程序冻结了大约 30 秒,然后没有任何变化,没有应用过滤器。我试过调试,我似乎无法找到问题所在!

编辑:最初的问题已经解决(我必须刷新图片框才能正确显示新图像。但是我在这里遇到了关于 prewitt 内核的另一个问题。

我收到此错误“附加信息:'-6' 的值对'red' 无效。'red' 应大于或等于 0 且小于或等于 255。”

而且我不确定要更改我的代码中的哪些内容来解决此问题。

初始化:

public partial class Form1 : Form
{
    private Image img;
    Bitmap grayscaleimage;
    double[][] AVGKernel = new double[11][];
    double[][] PrewittKernel = new double[11][];
    int[] AVGKernal1DH = new int[11];
    int[] AVGKernal1DV = new int[11];

    Bitmap tempBitmap;

    public Form1()
    {
        InitializeComponent();
        for (int i = 0; i < 11; i++)
        {
            AVGKernel[i] = new double[11];
            PrewittKernel[i] = new double[11];
            for (int j = 0; j < 11; j++)
            {
                AVGKernel[i][j] = 0;
                PrewittKernel[i][j] = 0;
                AVGKernal1DH[j] = 0;
                AVGKernal1DV[j] = 0;
            }
        }
}

打开按钮并将图片变成灰度:

private void OpenImageButton(object sender, EventArgs e)
    {
        OpenFileDialog openFileDialog = new OpenFileDialog();
        if (openFileDialog.ShowDialog() == DialogResult.OK)
        {
            this.img = Image.FromFile(openFileDialog.FileName);

            grayscaleimage = new Bitmap(img);
            int rgb;
            Color c;

            for (int y = 0; y < grayscaleimage.Height; y++)
                for (int x = 0; x < grayscaleimage.Width; x++)
                {
                    c = grayscaleimage.GetPixel(x, y);
                    rgb = (int)((c.R + c.G + c.B) / 3);
                    grayscaleimage.SetPixel(x, y, Color.FromArgb(rgb, rgb, rgb));
                }
            this.pictureBox1.BackgroundImage = grayscaleimage;
            pictureBox1.BackgroundImageLayout = ImageLayout.Zoom;
        }
    }

许多可用按钮的示例:

private void button5_Click(object sender, EventArgs e)
    {
        AVGKernel[0][0] = 1; AVGKernel[0][1] = 1; AVGKernel[0][2] = 1; AVGKernel[0][3] = 1; AVGKernel[0][4] = 1;
        AVGKernel[1][0] = 1; AVGKernel[1][1] = 1; AVGKernel[1][2] = 1; AVGKernel[1][3] = 1; AVGKernel[1][4] = 1;
        AVGKernel[2][0] = 1; AVGKernel[2][1] = 1; AVGKernel[2][2] = 1; AVGKernel[2][3] = 1; AVGKernel[2][4] = 1;
        AVGKernel[3][0] = 1; AVGKernel[3][1] = 1; AVGKernel[3][2] = 1; AVGKernel[3][3] = 1; AVGKernel[3][4] = 1;
        AVGKernel[4][0] = 1; AVGKernel[4][1] = 1; AVGKernel[4][2] = 1; AVGKernel[4][3] = 1; AVGKernel[4][4] = 1;

        kernal2DMultiplication(AVGKernel, 5);
        this.pictureBox1.BackgroundImage = tempBitmap;

    }

Prewitt 5x5 内核

 private void button13_Click(object sender, EventArgs e)
    {
        PrewittKernel[0][0] = 2; PrewittKernel[0][1] = 1; PrewittKernel[0][2] = 0; PrewittKernel[0][3] = -1; PrewittKernel[0][4] = -2;
        PrewittKernel[1][0] = 2; PrewittKernel[1][1] = 1; PrewittKernel[1][2] = 0; PrewittKernel[1][3] = -1; PrewittKernel[1][4] = -2;
        PrewittKernel[2][0] = 2; PrewittKernel[2][1] = 1; PrewittKernel[2][2] = 0; PrewittKernel[2][3] = -1; PrewittKernel[2][4] = -2;
        PrewittKernel[3][0] = 2; PrewittKernel[3][1] = 1; PrewittKernel[3][2] = 0; PrewittKernel[3][3] = -1; PrewittKernel[3][4] = -2;
        PrewittKernel[4][0] = 2; PrewittKernel[4][1] = 1; PrewittKernel[4][2] = 0; PrewittKernel[4][3] = -1; PrewittKernel[4][4] = -2;

        kernal2DMultiplication(PrewittKernel, 5);
        this.pictureBox1.BackgroundImage = tempBitmap;
        this.pictureBox1.Refresh();
    }

最后,被调用的函数:

private void kernal2DMultiplication(double[][] kernel, int size)
    {
        tempBitmap = grayscaleimage;
        double nrgb = 0;

        for (int i = 0; i < grayscaleimage.Width - size / 2; i++)
        {
            for (int j = 0; j < grayscaleimage.Height - size / 2; j++)
            {
                if (i >= size / 2 && j >= size / 2)
                {
                    for (int k = 0; k < size; k++)
                        for (int l = 0; l < size; l++)

                            nrgb += grayscaleimage.GetPixel(i + k - (size / 2), j + l - (size / 2)).R * kernel[k][l];
                            nrgb = nrgb / (size * size);

                    if (nrgb > 255)
                        nrgb = 255;

                    tempBitmap.SetPixel(i, j, Color.FromArgb((int)nrgb, (int)nrgb, (int)nrgb));

                }

            }

        }
    }
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1 回答 1

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问题是您正在BackgroundImage就地修改位图而不是复制,修改副本,然后将副本设置为BackgroundImage

    this.pictureBox1.BackgroundImage = grayscaleimage; // initially

    tempBitmap = grayscaleimage; 

    // Make changes to tempBitmap

    this.pictureBox1.BackgroundImage = tempBitmap; // actually still the same pointer

在这种BackgroundImage情况下,setter 不会强制重绘控件。要自己强制执行此操作,请致电Refresh()

    this.pictureBox1.Refresh();

为了提高性能,请考虑将多个调用替换为SetPixel对 的单个调用LockBits。参见例如这里

于 2014-11-03T19:50:31.183 回答