cs50 PSET4 - 过滤我的代码中的疑问和问题

Question

在 CS50 的 PSET4 上工作了一段时间，它需要创建四个函数，对输入图像应用各种效果。灰度、棕褐色、反射和模糊。

当我第一次完成代码时，当我检查它时，几乎没有任何代码可以工作。我通过基本上无意识地添加一堆变量来解决其中的大部分问题，这些变量由于某种原因解决了我的许多问题。

有人可以解释为什么原始代码不起作用并且仅实现了近似值吗？

这是原来的，然后更新的：

void grayscale(int height, int width, RGBTRIPLE image[height][width])
{
    for (int x = 0; x < height; x++) {
        for (int y = 0; y < width; y++) {
            BYTE avg = round((image[x][y].rgbtBlue + image[x][y].rgbtRed + image[x][y].rgbtGreen) / 3);
            image[x][y].rgbtBlue = avg;
            image[x][y].rgbtRed = avg;
            image[x][y].rgbtGreen = avg;
            }
    }
    return;
    }
void sepia(int height, int width, RGBTRIPLE image[height][width])
{
    for (int x = 0; x < height; x++) {
        for (int y = 0; y < width; y++) {
                BYTE originalRed = image[x][y].rgbtRed;
                BYTE originalGreen = image[x][y].rgbtGreen;
                BYTE originalBlue = image[x][y].rgbtBlue;
    
                image[x][y].rgbtRed = .393 * originalRed + .769 * originalGreen + .189 * originalBlue;
                image[x][y].rgbtGreen = .349 * originalRed + .686 * originalGreen + .168 * originalBlue;
                image[x][y].rgbtBlue = .272 * originalRed + .534 * originalGreen + .131 * originalBlue;
                if (image[x][y].rgbtRed > 255) {
                    image[x][y].rgbtRed = 255;
                }
                if (image[x][y].rgbtGreen > 255) {
                    image[x][y].rgbtGreen = 255;
                }
                if (image[x][y].rgbtBlue > 255) {
                    image[x][y].rgbtBlue = 255;
                }
            }
         }
        return;
    }

---

void grayscale(int height, int width, RGBTRIPLE image[height][width])
{
    for (int x = 0; x < height; x++) {
        for (int y = 0; y < width; y++) {
            int red = image[x][y].rgbtRed;
            int green = image[x][y].rgbtGreen;
            int blue = image[x][y].rgbtBlue;

            int avg = round(((float)red + (float)green + (float)blue) / 3);
            image[x][y].rgbtBlue = avg;
            image[x][y].rgbtRed = avg;
            image[x][y].rgbtGreen = avg;
            }
    }
    return;
}

// Convert image to sepia
void sepia(int height, int width, RGBTRIPLE image[height][width])
{
    for (int x = 0; x < height; x++) {
        for (int y = 0; y < width; y++) {
            int originalRed = image[x][y].rgbtRed;
            int originalGreen = image[x][y].rgbtGreen;
            int originalBlue = image[x][y].rgbtBlue;

            int sepiaRed = round(.393 * originalRed + .769 * originalGreen + .189 * originalBlue);
            int sepiaGreen = round(.349 * originalRed + .686 * originalGreen + .168 * originalBlue);
            int sepiaBlue = round(.272 * originalRed + .534 * originalGreen + .131 * originalBlue);

            if (sepiaRed > 255) {
                image[x][y].rgbtRed = 255;
            }
            else{
                image[x][y].rgbtRed = sepiaRed;
            }
            if (sepiaGreen > 255) {
                image[x][y].rgbtGreen = 255;
            }
            else{
                image[x][y].rgbtGreen = sepiaGreen;
            }
            if (sepiaBlue > 255) {
                image[x][y].rgbtBlue = 255;
            }
            else{
                image[x][y].rgbtBlue = sepiaBlue;
            }
        }
     }
    return;
}