CS50模糊功能仅正确计算中间像素+段错误

Question

// Blur image
void blur(int height, int width, RGBTRIPLE image[height][width])
{
    RGBTRIPLE blurred[height][width];
    int i = 0;
    int j = 0;
    int sumred;
    int sumgreen;
    int sumblue;
    for (i = 0; i < height; i++)
    {
        for (j = 0; j < width; j++)
        {
            if (i == 0 && j == 0) //edge case 1: top left corner
            {
                // ([i][j] + [i][j+1] + [i+1][j] + [i+1][j+1])/4
                sumred = image[i][j].rgbtRed + image[i][j+1].rgbtRed + image[i+1][j].rgbtRed + image[i+1][j+1].rgbtRed;
                blurred[i][j].rgbtRed = round(sumred / 4.0);
                sumgreen = image[i][j].rgbtGreen + image[i][j+1].rgbtGreen + image[i+1][j].rgbtGreen + image[i+1][j+1].rgbtGreen;
                blurred[i][j].rgbtGreen = round(sumgreen / 4.0);
                sumblue = image[i][j].rgbtBlue + image[i][j+1].rgbtBlue + image[i+1][j].rgbtBlue + image[i+1][j+1].rgbtBlue;
                blurred[i][j].rgbtBlue = round(sumblue / 4.0);
            }

            if (i == 0 && j > 0 && j < (width - 1)) //edgecase 2: top roll
            {
                // ([i][j-1] + [i][j] + [i][j+1] + [i+1][j-1] + [i+1][j] + [i+1][j+1])/6
                sumred = image[i][j-1].rgbtRed + image[i][j].rgbtRed + image[i][j+1].rgbtRed + image[i+1][j-1].rgbtRed + image[i+1][j].rgbtRed + image[i+1][j+1].rgbtRed;
                blurred[i][j].rgbtRed = round(sumred / 6.0);
                sumgreen = image[i][j-1].rgbtGreen + image[i][j].rgbtGreen + image[i][j+1].rgbtGreen + image[i+1][j-1].rgbtGreen + image[i+1][j].rgbtGreen + image[i+1][j+1].rgbtGreen;
                blurred[i][j].rgbtGreen = round(sumgreen / 6.0);
                sumblue = image[i][j-1].rgbtBlue + image[i][j].rgbtBlue + image[i][j+1].rgbtBlue + image[i+1][j-1].rgbtBlue + image[i+1][j].rgbtBlue + image[i+1][j+1].rgbtBlue;
                blurred[i][j].rgbtBlue = round(sumblue / 6.0);
            }

            if (i == 0 && j == (width - 1)) //edge case 3: top right corner
            {
                sumred = image[i][j-1].rgbtRed + image[i][j].rgbtRed + image[i+1][j-1].rgbtRed + image[i+1][j].rgbtRed;
                blurred[i][j].rgbtRed = round(sumred / 4.0);
                sumgreen = image[i][j-1].rgbtGreen + image[i][j].rgbtGreen + image[i+1][j-1].rgbtGreen + image[i+1][j].rgbtGreen;
                blurred[i][j].rgbtGreen = round(sumgreen / 4.0);
                sumblue = image[i][j-1].rgbtBlue + image[i][j].rgbtBlue + image[i+1][j-1].rgbtBlue + image[i+1][j].rgbtBlue;
                blurred[i][j].rgbtBlue = round(sumblue / 4.0);
            }

            if (i > 0 && i < (height - 1) && j == 0) //edge case 4: left most column
            {
                sumred = image[i-1][j].rgbtRed + image[i-1][j+1].rgbtRed + image[i][j].rgbtRed + image[i][j+1].rgbtRed + + image[i+1][j].rgbtRed + image[i+1][j+1].rgbtRed;
                blurred[i][j].rgbtRed = round(sumred / 6.0);
                sumgreen = image[i-1][j].rgbtGreen + image[i-1][j+1].rgbtGreen + image[i][j].rgbtGreen + image[i][j+1].rgbtGreen + image[i+1][j].rgbtGreen + image[i+1][j+1].rgbtGreen;
                blurred[i][j].rgbtGreen = round(sumgreen / 6.0);
                sumblue = image[i-1][j].rgbtBlue + image[i-1][j+1].rgbtBlue + image[i][j].rgbtBlue + image[i][j+1].rgbtBlue + image[i+1][j].rgbtBlue + image[i+1][j+1].rgbtBlue;
                blurred[i][j].rgbtBlue = round(sumblue / 6.0);
            }

            if (i == (height - 1) && j == 0) // edge case 5: bottom left corner
            {
                sumred = image[i-1][j].rgbtRed + image[i-1][j+1].rgbtRed + image[i][j].rgbtRed + image[i][j+1].rgbtRed;
                blurred[i][j].rgbtRed = round(sumred / 4.0);
                sumgreen = image[i-1][j].rgbtGreen + image[i-1][j+1].rgbtGreen + image[i][j].rgbtGreen + image[i][j+1].rgbtGreen;
                blurred[i][j].rgbtGreen = round(sumgreen / 4.0);
                sumblue = image[i-1][j].rgbtBlue + image[i-1][j+1].rgbtBlue + image[i][j].rgbtBlue + image[i][j+1].rgbtBlue;
                blurred[i][j].rgbtBlue = round(sumblue / 4.0);
            }

            if (i == (height - 1) && j > 0 && j < (width -1)) // edge case 6: bottom roll
            {
                sumred = image[i-1][j-1].rgbtRed + image[i-1][j].rgbtRed + image[i-1][j+1].rgbtRed + image[i][j-1].rgbtRed + image[i][j].rgbtRed + image[i][j+1].rgbtRed;
                blurred[i][j].rgbtRed = round(sumred / 6.0);
                sumgreen = image[i-1][j-1].rgbtGreen + image[i-1][j].rgbtGreen + image[i-1][j+1].rgbtGreen + image[i][j-1].rgbtGreen + image[i][j].rgbtGreen + image[i][j+1].rgbtGreen;
                blurred[i][j].rgbtGreen = round(sumgreen / 6.0);
                sumblue = image[i-1][j-1].rgbtBlue + image[i-1][j].rgbtBlue + image[i-1][j+1].rgbtBlue + image[i][j-1].rgbtBlue + image[i][j].rgbtBlue + image[i][j+1].rgbtBlue;
                blurred[i][j].rgbtBlue = round(sumblue / 6.0);
            }

            if (i == (height - 1) && j == (width - 1)) // edge case 7: bottom right corner
            {
                sumred = image[i-1][j-1].rgbtRed + image[i-1][j].rgbtRed + image[i][j-1].rgbtRed + image[i][j].rgbtRed;
                blurred[i][j].rgbtRed = round(sumred / 4.0);
                sumgreen = image[i-1][j-1].rgbtGreen + image[i-1][j].rgbtGreen + image[i][j-1].rgbtGreen + image[i][j].rgbtGreen;
                blurred[i][j].rgbtGreen = round(sumgreen / 4.0);
                sumblue = image[i-1][j-1].rgbtBlue + image[i-1][j].rgbtBlue + image[i][j-1].rgbtBlue + image[i][j].rgbtBlue;
                blurred[i][j].rgbtBlue = round(sumblue / 4.0);
            }

            if (i > 0 && i < (height - 1) && j == (width - 1)) // edge case 8: right most column
            {
                sumred = image[i-1][j-1].rgbtRed + image[i-1][j].rgbtRed + image[i][j-1].rgbtRed + image[i][j].rgbtRed + image[i+1][j-1].rgbtRed + image[i+1][j].rgbtRed;
                blurred[i][j].rgbtRed = round(sumred / 6.0);
                sumgreen = image[i-1][j-1].rgbtGreen + image[i-1][j].rgbtGreen + image[i][j-1].rgbtGreen + image[i][j].rgbtGreen + image[i+1][j-1].rgbtGreen + image[i+1][j].rgbtGreen;
                blurred[i][j].rgbtGreen = round(sumgreen / 6.0);
                sumblue = image[i-1][j-1].rgbtBlue + image[i-1][j].rgbtBlue + image[i][j-1].rgbtBlue + image[i][j].rgbtBlue + image[i+1][j-1].rgbtBlue + image[i+1][j].rgbtBlue;
                blurred[i][j].rgbtBlue = round(sumblue / 6.0);
            }

            else // everything else srrounded by 8 pixels
            {
                sumred = image[i-1][j-1].rgbtRed + image[i-1][j].rgbtRed + image[i-1][j+1].rgbtRed + image[i][j-1].rgbtRed + image[i][j].rgbtRed + image[i][j+1].rgbtRed + image[i+1][j-1].rgbtRed + image[i+1][j].rgbtRed + image[i+1][j+1].rgbtRed;
                blurred[i][j].rgbtRed = round(sumred / 9.0);
                sumgreen = image[i-1][j-1].rgbtGreen + image[i-1][j].rgbtGreen + image[i-1][j+1].rgbtGreen + image[i][j-1].rgbtGreen + image[i][j].rgbtGreen + image[i][j+1].rgbtGreen + image[i+1][j-1].rgbtGreen + image[i+1][j].rgbtGreen + image[i+1][j+1].rgbtGreen;
                blurred[i][j].rgbtGreen = round(sumgreen / 9.0);
                sumblue = image[i-1][j-1].rgbtBlue + image[i-1][j].rgbtBlue + image[i-1][j+1].rgbtBlue + image[i][j-1].rgbtBlue + image[i][j].rgbtBlue + image[i][j+1].rgbtBlue + image[i+1][j-1].rgbtBlue + image[i+1][j].rgbtBlue + image[i+1][j+1].rgbtBlue;
                blurred[i][j].rgbtBlue = round(sumblue / 9.0);
            }
        }
    }

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

这可能是解决这个问题的最简单的方法（但它不起作用） 我已经检查了所有循环条件为 height-1 或 width-1，考虑了所有 8 个边缘情况，不确定为什么会发生段错误。

检查 bmp 文件时出现段错误。

**下面是查看50个结果

使用示例 3x3 图像进行测试

第一行：(10,20,30),(40,50,60),(70,80,90)

第二行：(110, 130, 140), (120, 140, 150), (130, 150, 160)

第三行：(200, 210, 220), (220, 230, 240), (240, 250, 255)

预期输出：

70 85 95

80 95 105

90 105 115

117 130 140

127 140 149

137 150 159

163 178 188

170 185 194

178 193 201

实际产量：

42 52 57

56 67 71

76 87 96

100 112 121

127 140 149

137 150 159

121 132 139

113 123 129

101 109 142**

Answer 1

// Blur image
void blur(int height, int width, RGBTRIPLE image[height][width])
{
RGBTRIPLE blurred[height][width];
int i = 0;
int j = 0;
int sumred = 0;
int sumgreen = 0;
int sumblue = 0;

for (i = 0; i < height; i++)
{
    for (j = 0; j < width; j++)
    {
        int count_in = 0;
        sumred = 0;
        sumgreen = 0;
        sumblue = 0;
        // loop from grid 0 (i - 1, j - 1) to grid 8 (i + 1, j + 1) and check if anything out of bounds
        // count_in is the number of pixels in a 9-grid that's inside bounds
        for (int x = i - 1; x < i + 2; x++)
        {
            for (int y = j - 1; y < j + 2; y++)
            {

                if (x < 0 || x > height - 1 || y < 0 || y > width - 1)
                {
                    continue;
                }
                else
                {
                    sumred = image[x][y].rgbtRed + sumred;
                    sumgreen = image[x][y].rgbtGreen + sumgreen;
                    sumblue = image[x][y].rgbtBlue + sumblue;
                    count_in++;
                }
            }
        }
        blurred[i][j].rgbtRed = round(sumred / (float) count_in);
        blurred[i][j].rgbtGreen = round(sumgreen / (float) count_in);
        blurred[i][j].rgbtBlue = round(sumblue / (float) count_in);
    }
}

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

停止使用unga Bunga方法并决定在像素[i][j]周围的9网格图案内循环并检查是否超出范围并使用

continue

跳过它们

此代码通过了 check50。谢谢各位评论