数字影像金字塔三层不调用库函数能够输出三张图片且能够在visual 2019 上运行的c语言代码

以下是一个简单的数字影像金字塔三层的C语言代码示例，可以在Visual Studio 2019上运行，无需调用库函数：

#include <stdio.h>
#include <stdlib.h>

#define WIDTH 256
#define HEIGHT 256

int main()
{
    // 读取原始图像
    FILE* fp = fopen("lena.raw", "rb");
    unsigned char* img = (unsigned char*)malloc(WIDTH * HEIGHT * sizeof(unsigned char));
    fread(img, sizeof(unsigned char), WIDTH * HEIGHT, fp);
    fclose(fp);

    // 申请三层金字塔图像空间
    unsigned char* img1 = (unsigned char*)malloc(WIDTH / 2 * HEIGHT / 2 * sizeof(unsigned char));
    unsigned char* img2 = (unsigned char*)malloc(WIDTH / 4 * HEIGHT / 4 * sizeof(unsigned char));
    unsigned char* img3 = (unsigned char*)malloc(WIDTH / 8 * HEIGHT / 8 * sizeof(unsigned char));

    // 第一层金字塔
    for (int i = 0; i < HEIGHT / 2; i++) {
        for (int j = 0; j < WIDTH / 2; j++) {
            img1[i * WIDTH / 2 + j] = img[i * WIDTH * 2 + j * 2];
        }
    }

    // 第二层金字塔
    for (int i = 0; i < HEIGHT / 4; i++) {
        for (int j = 0; j < WIDTH / 4; j++) {
            img2[i * WIDTH / 4 + j] = img1[i * WIDTH + j * 2];
        }
    }

    // 第三层金字塔
    for (int i = 0; i < HEIGHT / 8; i++) {
        for (int j = 0; j < WIDTH / 8; j++) {
            img3[i * WIDTH / 8 + j] = img2[i * WIDTH / 2 + j * 2];
        }
    }

    // 输出三张金字塔图像
    fp = fopen("lena_1.raw", "wb");
    fwrite(img1, sizeof(unsigned char), WIDTH / 2 * HEIGHT / 2, fp);
    fclose(fp);

    fp = fopen("lena_2.raw", "wb");
    fwrite(img2, sizeof(unsigned char), WIDTH / 4 * HEIGHT / 4, fp);
    fclose(fp);

    fp = fopen("lena_3.raw", "wb");
    fwrite(img3, sizeof(unsigned char), WIDTH / 8 * HEIGHT / 8, fp);
    fclose(fp);

    free(img);
    free(img1);
    free(img2);
    free(img3);

    return 0;
}

上述代码中，我们首先读取了一个名为"lena.raw"的256x256的灰度图像，然后分别对其进行了三层下采样，得到了分别为128x128、64x64、32x32的三张金字塔图像，最后将三张图像输出到文件"lena_1.raw"、"lena_2.raw"和"lena_3.raw"中。在实际使用中，我们可以根据需要修改图像的尺寸和文件名等参数。