CS50 滤镜“边缘”返回白色图像

【问题标题】：CS50 Filter 'Edge' returns white imageCS50 滤镜“边缘”返回白色图像
【发布时间】：2021-06-24 10:45:58
【问题描述】：

我一直在研究哈佛 CS50 的“过滤器”问题，但在 edges 部分有点卡住了。

我一直在尝试使用这个算法来解决它：

  • 逐个像素地浏览整个图像。图像是RGBTRIPLE 类型的矩阵，称为image[height][width]
  • 检查当前像素是角落、边缘还是中间某处（“其他”情况）
  • 将该像素以及“相邻”像素与相应的g(x) 和g(y) 值相乘，计算g(x)^2 + g(y)^2 的平方根，将其四舍五入，然后将该值导出到另一个矩阵image2[height][width]。

我在下面提供的代码是我解决问题的尝试。我使用了与blur 算法中相同的验证（检查角、边缘或中间），并且成功了。

// Detect edges
void edges(int height, int width, RGBTRIPLE image[height][width])
{
    RGBTRIPLE gx, gy;
    RGBTRIPLE image2[height][width];

    for (int i = 0; i < height; i++)
    {
        for (int j = 0; j < width; j++)
        {
            gx.rgbtRed = 0;
            gx.rgbtGreen = 0;
            gx.rgbtBlue = 0;

            gy.rgbtRed = 0;
            gy.rgbtGreen = 0;
            gy.rgbtBlue = 0;

            if (i == 0 && j == 0)
            {
                gx.rgbtRed += 0 * image[i][j].rgbtRed;
                gx.rgbtGreen += 0 * image[i][j].rgbtGreen;
                gx.rgbtBlue += 0 * image[i][j].rgbtBlue;

                gy.rgbtRed += 0 * image[i][j].rgbtRed;
                gy.rgbtGreen += 0 * image[i][j].rgbtGreen;
                gy.rgbtBlue += 0 * image[i][j].rgbtBlue;

                gx.rgbtRed += 0 * image[i+1][j].rgbtRed;
                gx.rgbtGreen += 0 * image[i+1][j].rgbtGreen;
                gx.rgbtBlue += 0 * image[i+1][j].rgbtBlue;

                gy.rgbtRed += 2 * image[i+1][j].rgbtRed;
                gy.rgbtGreen += 2 * image[i+1][j].rgbtGreen;
                gy.rgbtBlue += 2 * image[i+1][j].rgbtBlue;

                gx.rgbtRed += 2 * image[i][j+1].rgbtRed;
                gx.rgbtGreen += 2 * image[i][j+1].rgbtGreen;
                gx.rgbtBlue += 2 * image[i][j+1].rgbtBlue;

                gy.rgbtRed += 0 * image[i][j+1].rgbtRed;
                gy.rgbtGreen += 0 * image[i][j+1].rgbtGreen;
                gy.rgbtBlue += 0 * image[i][j+1].rgbtBlue;

                gx.rgbtRed += image[i+1][j+1].rgbtRed;
                gx.rgbtGreen += image[i+1][j+1].rgbtGreen;
                gx.rgbtBlue += image[i+1][j+1].rgbtBlue;

                gy.rgbtRed += image[i+1][j+1].rgbtRed;
                gy.rgbtGreen += image[i+1][j+1].rgbtGreen;
                gy.rgbtBlue += image[i+1][j+1].rgbtBlue;
            }

            else if (i == 0 && j == width-1)
            {
                gx.rgbtRed += 0 * image[i][j].rgbtRed;
                gx.rgbtGreen += 0 * image[i][j].rgbtGreen;
                gx.rgbtBlue += 0 * image[i][j].rgbtBlue;

                gy.rgbtRed += 0 * image[i][j].rgbtRed;
                gy.rgbtGreen += 0 * image[i][j].rgbtGreen;
                gy.rgbtBlue += 0 * image[i][j].rgbtBlue;

                gx.rgbtRed += -2 * image[i][j-1].rgbtRed;
                gx.rgbtGreen += -2 * image[i][j-1].rgbtGreen;
                gx.rgbtBlue += -2 * image[i][j-1].rgbtBlue;

                gy.rgbtRed += 0 * image[i][j-1].rgbtRed;
                gy.rgbtGreen += 0 * image[i][j-1].rgbtGreen;
                gy.rgbtBlue += 0 * image[i][j-1].rgbtBlue;

                gx.rgbtRed += 0 * image[i+1][j].rgbtRed;
                gx.rgbtGreen += 0 * image[i+1][j].rgbtGreen;
                gx.rgbtBlue += 0 * image[i+1][j].rgbtBlue;

                gy.rgbtRed += 2 * image[i+1][j].rgbtRed;
                gy.rgbtGreen += 2 * image[i+1][j].rgbtGreen;
                gy.rgbtBlue += 2 * image[i+1][j].rgbtBlue;

                gx.rgbtRed += -1 * image[i+1][j-1].rgbtRed;
                gx.rgbtGreen += -1 * image[i+1][j-1].rgbtGreen;
                gx.rgbtBlue += -1 * image[i+1][j-1].rgbtBlue;

                gy.rgbtRed += image[i+1][j-1].rgbtRed;
                gy.rgbtGreen += image[i+1][j-1].rgbtGreen;
                gy.rgbtBlue += image[i+1][j-1].rgbtBlue;
            }

            else if (i == height-1 && j == 0)
            {
                gx.rgbtRed += 0 * image[i][j].rgbtRed;
                gx.rgbtGreen += 0 * image[i][j].rgbtGreen;
                gx.rgbtBlue += 0 * image[i][j].rgbtBlue;

                gy.rgbtRed += 0 * image[i][j].rgbtRed;
                gy.rgbtGreen += 0 * image[i][j].rgbtGreen;
                gy.rgbtBlue += 0 * image[i][j].rgbtBlue;

                gx.rgbtRed += 0 * image[i-1][j].rgbtRed;
                gx.rgbtGreen += 0 * image[i-1][j].rgbtGreen;
                gx.rgbtBlue += 0 * image[i-1][j].rgbtBlue;

                gy.rgbtRed += -2 * image[i-1][j].rgbtRed;
                gy.rgbtGreen += -2 * image[i-1][j].rgbtGreen;
                gy.rgbtBlue += -2 * image[i-1][j].rgbtBlue;

                gx.rgbtRed += image[i-1][j+1].rgbtRed;
                gx.rgbtGreen += image[i-1][j+1].rgbtGreen;
                gx.rgbtBlue +=  image[i-1][j+1].rgbtBlue;

                gy.rgbtRed += -1 * image[i][j].rgbtRed;
                gy.rgbtGreen += -1 * image[i][j].rgbtGreen;
                gy.rgbtBlue += -1 * image[i][j].rgbtBlue;

                gx.rgbtRed += 2 * image[i][j+1].rgbtRed;
                gx.rgbtGreen += 2 * image[i][j+1].rgbtGreen;
                gx.rgbtBlue += 2 * image[i][j+1].rgbtBlue;

                gy.rgbtRed += 0 * image[i][j+1].rgbtRed;
                gy.rgbtGreen += 0 * image[i][j+1].rgbtGreen;
                gy.rgbtBlue += 0 * image[i][j+1].rgbtBlue;
            }

            else if (i == height-1 && j == width-1)
            {
                gx.rgbtRed += 0 * image[i][j].rgbtRed;
                gx.rgbtGreen += 0 * image[i][j].rgbtGreen;
                gx.rgbtBlue += 0 * image[i][j].rgbtBlue;

                gy.rgbtRed += 0 * image[i][j].rgbtRed;
                gy.rgbtGreen += 0 * image[i][j].rgbtGreen;
                gy.rgbtBlue += 0 * image[i][j].rgbtBlue;

                gx.rgbtRed += 0 * image[i-1][j].rgbtRed;
                gx.rgbtGreen += 0 * image[i-1][j].rgbtGreen;
                gx.rgbtBlue += 0 * image[i-1][j].rgbtBlue;

                gy.rgbtRed += -2 * image[i-1][j].rgbtRed;
                gy.rgbtGreen += -2 * image[i-1][j].rgbtGreen;
                gy.rgbtBlue += -2 * image[i-1][j].rgbtBlue;

                gx.rgbtRed += -1 * image[i-1][j-1].rgbtRed;
                gx.rgbtGreen += -1 * image[i-1][j-1].rgbtGreen;
                gx.rgbtBlue += -1 * image[i-1][j-1].rgbtBlue;

                gy.rgbtRed += -1 * image[i-1][j-1].rgbtRed;
                gy.rgbtGreen += -1 * image[i-1][j-1].rgbtGreen;
                gy.rgbtBlue += -1 * image[i-1][j-1].rgbtBlue;

                gx.rgbtRed += -2 * image[i][j-1].rgbtRed;
                gx.rgbtGreen += -2 * image[i][j-1].rgbtGreen;
                gx.rgbtBlue += -2 * image[i][j-1].rgbtBlue;

                gy.rgbtRed += 0 * image[i-1][j-1].rgbtRed;
                gy.rgbtGreen += 0 * image[i-1][j-1].rgbtGreen;
                gy.rgbtBlue += 0 * image[i-1][j-1].rgbtBlue;
            }

            else if (i == 0)
            {
                gx.rgbtRed += 0 * image[i][j].rgbtRed;
                gx.rgbtGreen += 0 * image[i][j].rgbtGreen;
                gx.rgbtBlue += 0 * image[i][j].rgbtBlue;

                gy.rgbtRed += 0 * image[i][j].rgbtRed;
                gy.rgbtGreen += 0 * image[i][j].rgbtGreen;
                gy.rgbtBlue += 0 * image[i][j].rgbtBlue;

                gx.rgbtRed += -2 * image[i][j-1].rgbtRed;
                gx.rgbtGreen += -2 * image[i][j-1].rgbtGreen;
                gx.rgbtBlue += -2 * image[i][j-1].rgbtBlue;

                gy.rgbtRed += image[i][j-1].rgbtRed;
                gy.rgbtGreen += image[i][j-1].rgbtGreen;
                gy.rgbtBlue += image[i][j-1].rgbtBlue;

                gx.rgbtRed += -1 * image[i+1][j-1].rgbtRed;
                gx.rgbtGreen += -1 * image[i+1][j-1].rgbtGreen;
                gx.rgbtBlue += -1 * image[i+1][j-1].rgbtBlue;

                gy.rgbtRed += image[i+1][j-1].rgbtRed;
                gy.rgbtGreen += image[i+1][j-1].rgbtGreen;
                gy.rgbtBlue += image[i+1][j-1].rgbtBlue;

                gx.rgbtRed += 0 * image[i+1][j].rgbtRed;
                gx.rgbtGreen += 0 * image[i+1][j].rgbtGreen;
                gx.rgbtBlue += 0 * image[i+1][j].rgbtBlue;

                gy.rgbtRed += 2 * image[i+1][j].rgbtRed;
                gy.rgbtGreen += 2 * image[i+1][j].rgbtGreen;
                gy.rgbtBlue += 2 * image[i+1][j].rgbtBlue;

                gx.rgbtRed += image[i+1][j+1].rgbtRed;
                gx.rgbtGreen += image[i+1][j+1].rgbtGreen;
                gx.rgbtBlue += image[i+1][j+1].rgbtBlue;

                gy.rgbtRed += image[i+1][j+1].rgbtRed;
                gy.rgbtGreen += image[i+1][j+1].rgbtGreen;
                gy.rgbtBlue += image[i+1][j+1].rgbtBlue;

                gx.rgbtRed += 2 * image[i][j+1].rgbtRed;
                gx.rgbtGreen += 2 * image[i][j+1].rgbtGreen;
                gx.rgbtBlue += 2 * image[i][j+1].rgbtBlue;

                gy.rgbtRed += 0 * image[i][j+1].rgbtRed;
                gy.rgbtGreen += 0 * image[i][j+1].rgbtGreen;
                gy.rgbtBlue += 0 * image[i][j+1].rgbtBlue;
            }

            else if (i == height-1)
            {
                gx.rgbtRed += 0 * image[i][j].rgbtRed;
                gx.rgbtGreen += 0 * image[i][j].rgbtGreen;
                gx.rgbtBlue += 0 * image[i][j].rgbtBlue;

                gy.rgbtRed += 0 * image[i][j].rgbtRed;
                gy.rgbtGreen += 0 * image[i][j].rgbtGreen;
                gy.rgbtBlue += 0 * image[i][j].rgbtBlue;

                gx.rgbtRed += -2 * image[i][j-1].rgbtRed;
                gx.rgbtGreen += -2 * image[i][j-1].rgbtGreen;
                gx.rgbtBlue += -2 * image[i][j-1].rgbtBlue;

                gy.rgbtRed += 0 * image[i][j-1].rgbtRed;
                gy.rgbtGreen += 0 * image[i][j-1].rgbtGreen;
                gy.rgbtBlue += 0 * image[i][j-1].rgbtBlue;

                gx.rgbtRed += -1 * image[i-1][j-1].rgbtRed;
                gx.rgbtGreen += -1 * image[i-1][j-1].rgbtGreen;
                gx.rgbtBlue += -1 * image[i-1][j-1].rgbtBlue;

                gy.rgbtRed += -1 * image[i-1][j-1].rgbtRed;
                gy.rgbtGreen += -1 * image[i-1][j-1].rgbtGreen;
                gy.rgbtBlue += -1 * image[i-1][j-1].rgbtBlue;

                gx.rgbtRed += 0 * image[i-1][j].rgbtRed;
                gx.rgbtGreen += 0 * image[i-1][j].rgbtGreen;
                gx.rgbtBlue += 0 * image[i-1][j].rgbtBlue;

                gy.rgbtRed += -2 * image[i-1][j].rgbtRed;
                gy.rgbtGreen += -2 * image[i-1][j].rgbtGreen;
                gy.rgbtBlue += -2 * image[i-1][j].rgbtBlue;

                gx.rgbtRed += image[i-1][j+1].rgbtRed;
                gx.rgbtGreen += image[i-1][j+1].rgbtGreen;
                gx.rgbtBlue += image[i-1][j+1].rgbtBlue;

                gy.rgbtRed += 0 * image[i-1][j+1].rgbtRed;
                gy.rgbtGreen += 0 * image[i-1][j+1].rgbtGreen;
                gy.rgbtBlue += 0 * image[i-1][j+1].rgbtBlue;

                gx.rgbtRed += 2 * image[i][j+1].rgbtRed;
                gx.rgbtGreen += 2 * image[i][j+1].rgbtGreen;
                gx.rgbtBlue += 2 * image[i][j+1].rgbtBlue;

                gy.rgbtRed += 0 * image[i][j+1].rgbtRed;
                gy.rgbtGreen += 0 * image[i][j+1].rgbtGreen;
                gy.rgbtBlue += 0 * image[i][j+1].rgbtBlue;
            }

            else if (j == 0)
            {
                gx.rgbtRed += 0 * image[i][j].rgbtRed;
                gx.rgbtGreen += 0 * image[i][j].rgbtGreen;
                gx.rgbtBlue += 0 * image[i][j].rgbtBlue;

                gy.rgbtRed += 0 * image[i][j].rgbtRed;
                gy.rgbtGreen += 0 * image[i][j].rgbtGreen;
                gy.rgbtBlue += 0 * image[i][j].rgbtBlue;

                gx.rgbtRed += 0 * image[i-1][j].rgbtRed;
                gx.rgbtGreen += 0 * image[i-1][j].rgbtGreen;
                gx.rgbtBlue += 0 * image[i-1][j].rgbtBlue;

                gy.rgbtRed += -2 * image[i-1][j].rgbtRed;
                gy.rgbtGreen += -2 * image[i-1][j].rgbtGreen;
                gy.rgbtBlue += -2 * image[i-1][j].rgbtBlue;

                gx.rgbtRed += image[i-1][j+1].rgbtRed;
                gx.rgbtGreen += image[i-1][j+1].rgbtGreen;
                gx.rgbtBlue += image[i-1][j+1].rgbtBlue;

                gy.rgbtRed += -1 * image[i-1][j+1].rgbtRed;
                gy.rgbtGreen += -1 * image[i-1][j+1].rgbtGreen;
                gy.rgbtBlue += -1 * image[i-1][j+1].rgbtBlue;

                gx.rgbtRed += 2 * image[i][j+1].rgbtRed;
                gx.rgbtGreen += 2 * image[i][j+1].rgbtGreen;
                gx.rgbtBlue += 2 * image[i][j+1].rgbtBlue;

                gy.rgbtRed += 0 * image[i][j+1].rgbtRed;
                gy.rgbtGreen += 0 * image[i][j+1].rgbtGreen;
                gy.rgbtBlue += 0 * image[i][j+1].rgbtBlue;

                gx.rgbtRed += image[i+1][j+1].rgbtRed;
                gx.rgbtGreen += image[i+1][j+1].rgbtGreen;
                gx.rgbtBlue += image[i+1][j+1].rgbtBlue;

                gy.rgbtRed += image[i+1][j+1].rgbtRed;
                gy.rgbtGreen += image[i+1][j+1].rgbtGreen;
                gy.rgbtBlue += image[i+1][j+1].rgbtBlue;

                gx.rgbtRed += 0 * image[i+1][j].rgbtRed;
                gx.rgbtGreen += 0 * image[i+1][j].rgbtGreen;
                gx.rgbtBlue += 0 * image[i+1][j].rgbtBlue;

                gy.rgbtRed += 2 * image[i+1][j].rgbtRed;
                gy.rgbtGreen += 2 * image[i+1][j].rgbtGreen;
                gy.rgbtBlue += 2 * image[i+1][j].rgbtBlue;
            }

            else if (j == width-1)
            {
                gx.rgbtRed += 0 * image[i][j].rgbtRed;
                gx.rgbtGreen += 0 * image[i][j].rgbtGreen;
                gx.rgbtBlue += 0 * image[i][j].rgbtBlue;

                gy.rgbtRed += 0 * image[i][j].rgbtRed;
                gy.rgbtGreen += 0 * image[i][j].rgbtGreen;
                gy.rgbtBlue += 0 * image[i][j].rgbtBlue;

                gx.rgbtRed += 0 * image[i-1][j].rgbtRed;
                gx.rgbtGreen += 0 * image[i-1][j].rgbtGreen;
                gx.rgbtBlue += 0 * image[i-1][j].rgbtBlue;

                gy.rgbtRed += -2 * image[i-1][j].rgbtRed;
                gy.rgbtGreen += -2 * image[i-1][j].rgbtGreen;
                gy.rgbtBlue += -2 * image[i-1][j].rgbtBlue;

                gx.rgbtRed += -1 * image[i-1][j-1].rgbtRed;
                gx.rgbtGreen += -1 * image[i-1][j-1].rgbtGreen;
                gx.rgbtBlue += -1 * image[i-1][j-1].rgbtBlue;

                gy.rgbtRed += -1 * image[i-1][j-1].rgbtRed;
                gy.rgbtGreen += -1 * image[i-1][j-1].rgbtGreen;
                gy.rgbtBlue += -1 * image[i-1][j-1].rgbtBlue;

                gx.rgbtRed += -2 * image[i][j-1].rgbtRed;
                gx.rgbtGreen += -2 * image[i][j-1].rgbtGreen;
                gx.rgbtBlue += -2 * image[i][j-1].rgbtBlue;

                gy.rgbtRed += 0 * image[i][j-1].rgbtRed;
                gy.rgbtGreen += 0 * image[i][j-1].rgbtGreen;
                gy.rgbtBlue += 0 * image[i][j-1].rgbtBlue;

                gx.rgbtRed += -1 * image[i+1][j-1].rgbtRed;
                gx.rgbtGreen += -1 * image[i+1][j-1].rgbtGreen;
                gx.rgbtBlue += -1 * image[i+1][j-1].rgbtBlue;

                gy.rgbtRed += image[i+1][j-1].rgbtRed;
                gy.rgbtGreen += image[i+1][j-1].rgbtGreen;
                gy.rgbtBlue += image[i+1][j-1].rgbtBlue;

                gx.rgbtRed += 0 * image[i+1][j].rgbtRed;
                gx.rgbtGreen += 0 * image[i+1][j].rgbtGreen;
                gx.rgbtBlue += 0 * image[i+1][j].rgbtBlue;

                gy.rgbtRed += 2 * image[i+1][j].rgbtRed;
                gy.rgbtGreen += 2 * image[i+1][j].rgbtGreen;
                gy.rgbtBlue += 2 * image[i+1][j].rgbtBlue;
            }

            else
            {
                gx.rgbtRed += 0 * image[i][j].rgbtRed;
                gx.rgbtGreen += 0 * image[i][j].rgbtGreen;
                gx.rgbtBlue += 0 * image[i][j].rgbtBlue;

                gy.rgbtRed += 0 * image[i][j].rgbtRed;
                gy.rgbtGreen += 0 * image[i][j].rgbtGreen;
                gy.rgbtBlue += 0 * image[i][j].rgbtBlue;

                gx.rgbtRed += -1 * image[i-1][j-1].rgbtRed;
                gx.rgbtGreen += -1 * image[i-1][j-1].rgbtGreen;
                gx.rgbtBlue += -1 * image[i-1][j-1].rgbtBlue;

                gy.rgbtRed += -1 * image[i-1][j-1].rgbtRed;
                gy.rgbtGreen += -1 * image[i-1][j-1].rgbtGreen;
                gy.rgbtBlue += -1 * image[i-1][j-1].rgbtBlue;

                gx.rgbtRed += 0 * image[i-1][j].rgbtRed;
                gx.rgbtGreen += 0 * image[i-1][j].rgbtGreen;
                gx.rgbtBlue += 0 * image[i-1][j].rgbtBlue;

                gy.rgbtRed += -2 * image[i-1][j].rgbtRed;
                gy.rgbtGreen += -2 * image[i-1][j].rgbtGreen;
                gy.rgbtBlue += -2 * image[i-1][j].rgbtBlue;

                gx.rgbtRed += image[i-1][j+1].rgbtRed;
                gx.rgbtGreen += image[i-1][j+1].rgbtGreen;
                gx.rgbtBlue += image[i-1][j+1].rgbtBlue;

                gy.rgbtRed += -1 * image[i-1][j+1].rgbtRed;
                gy.rgbtGreen += -1 * image[i-1][j+1].rgbtGreen;
                gy.rgbtBlue += -1 * image[i-1][j+1].rgbtBlue;

                gx.rgbtRed += -2 * image[i][j-1].rgbtRed;
                gx.rgbtGreen += -2 * image[i][j-1].rgbtGreen;
                gx.rgbtBlue += -2 * image[i][j-1].rgbtBlue;

                gy.rgbtRed += 0 * image[i][j-1].rgbtRed;
                gy.rgbtGreen += 0 * image[i][j-1].rgbtGreen;
                gy.rgbtBlue += 0 * image[i][j-1].rgbtBlue;

                gx.rgbtRed += 2 * image[i][j+1].rgbtRed;
                gx.rgbtGreen += 2 * image[i][j+1].rgbtGreen;
                gx.rgbtBlue += 2 * image[i][j+1].rgbtBlue;

                gy.rgbtRed += 0 * image[i][j+1].rgbtRed;
                gy.rgbtGreen += 0 * image[i][j+1].rgbtGreen;
                gy.rgbtBlue += 0 * image[i][j+1].rgbtBlue;

                gx.rgbtRed += -1 * image[i+1][j-1].rgbtRed;
                gx.rgbtGreen += -1 * image[i+1][j-1].rgbtGreen;
                gx.rgbtBlue += -1 * image[i+1][j-1].rgbtBlue;

                gy.rgbtRed += image[i+1][j-1].rgbtRed;
                gy.rgbtGreen += image[i+1][j-1].rgbtGreen;
                gy.rgbtBlue += image[i+1][j-1].rgbtBlue;

                gx.rgbtRed += 0 * image[i+1][j].rgbtRed;
                gx.rgbtGreen += 0 * image[i+1][j].rgbtGreen;
                gx.rgbtBlue += 0 * image[i+1][j].rgbtBlue;

                gy.rgbtRed += 2 * image[i+1][j].rgbtRed;
                gy.rgbtGreen += 2 * image[i+1][j].rgbtGreen;
                gy.rgbtBlue += 2 * image[i+1][j].rgbtBlue;

                gx.rgbtRed += image[i+1][j+1].rgbtRed;
                gx.rgbtGreen += image[i+1][j+1].rgbtGreen;
                gx.rgbtBlue += image[i+1][j+1].rgbtBlue;

                gy.rgbtRed += image[i+1][j+1].rgbtRed;
                gy.rgbtGreen += image[i+1][j+1].rgbtGreen;
                gy.rgbtBlue += image[i+1][j+1].rgbtBlue;
            }

            int redVal = (int)round(sqrt(gx.rgbtRed * gx.rgbtRed + gy.rgbtRed * gy.rgbtRed));
            int greenVal = (int)round(sqrt(gx.rgbtGreen * gx.rgbtGreen + gy.rgbtGreen * gy.rgbtGreen));
            int blueVal = (int)round(sqrt(gx.rgbtBlue * gx.rgbtBlue + gy.rgbtBlue * gy.rgbtBlue));

            if (redVal > 255) redVal = 255;
            if (greenVal > 255) greenVal = 255;
            if (blueVal > 255) blueVal = 255;

            image2[i][j].rgbtRed = redVal;
            image2[i][j].rgbtGreen = greenVal;
            image2[i][j].rgbtBlue = blueVal;
        }
    }

    for (int i = 0; i < height; i++)
    {
        for (int j = 0; j < width; j++)
        {
            image[i][j].rgbtRed = image2[i][j].rgbtRed;
            image[i][j].rgbtGreen = image2[i][j].rgbtGreen;
            image[i][j].rgbtBlue = image2[i][j].rgbtBlue;
        }
    }
    return;
}

我的代码有很多行，因为它多次使用相同的操作（这是我设法解决问题的最简单方法）。

此外，if 语句中的乘法常数只是矩阵gx 和gy 的元素。我无缘无故地用gx 和gy 表示这些乘法的结果。我不想为这两个声明两个单独的矩阵，所以我对它们进行了硬编码。

我什至尝试手动验证自己，并检查是否使用printf() 正确识别了角落，并且一切正常。

问题是，当我使用check50 时，这是我的输出：

此外，提供的名为yard.bmp 的图像被转换为​​如下所示的“yardEdges.bmp”：

从我的角度来看，那是很多白色的，我无法从这张照片中识别出任何边缘。

首先，请不要评判我的编码方式，我只是发现这是解决“边缘”的最简单（也是最长和最无聊）的方式。

另外，我不认为验证（代码中的这 9 个 if 语句）会导致任何问题，也不会导致任何问题（乘法等）。我手动验证了所有这些，我很确定它们是正确的（不过我可能错了）。

我不是要求某人来验证这些陈述。我只是好奇我做错了什么，也许有人能看到我没有看到的东西。

谢谢！

【问题讨论】：

  • @Gerhardh 我不认为 gx 和 gy 作为 Brian 在演练中提到的矩阵。如果我没有使用RGBTRIPLE作为这两个变量的类型，我需要为每种颜色声明gxRed、gxGreen等
  • @Gerhardh 没关系。多亏了你，我设法做到了。仍然有最后 2 个错误，但可能是来自验证。我需要重新检查我的 if 语句。
  • @Gerhardh 我考虑过删除+= 0*... 块，但我只是想在删除它们之前确保每个添加都是正确的。也许应该有另一个数字而不是 0 他们。一切正常后肯定会删除它们。
  • @Gerhardh 另外，设法解决了我所有的错误。能否请您在答案中重写您的评论，以便我将其标记为正确答案？

标签： c filter cs50 edge-detection edx


【解决方案1】：

您在计算中使用了错误的数据类型：

RGBTRIPLE gx, gy;

这种类型能够为每个通道保存 8 位值。 当您为每个通道添加单独的组件时，您很容易在一个或多个通道中出现溢出。这会挫败您稍后将每个频道限制为255 的尝试。

为避免这种情况，只需创建另一个结构：

struct {
  uint32_t rgbtRed;
  uint32_t rgbtGreen;
  uint32_t rgbtBlue;
} gx,gy;

这将允许累加而不会溢出。

【讨论】：

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