数字影像金字塔c语言代码

数字影像金字塔可以通过递归实现，以下是一个简单的 C 语言代码实现：

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

#define MAX_LEVELS 10   // 最大金字塔层数

// 读取 BMP 文件头信息
void read_bmp_header(FILE *fp, int *width, int *height) {
    fseek(fp, 18, SEEK_SET);
    fread(width, sizeof(int), 1, fp);
    fread(height, sizeof(int), 1, fp);
}

// 读取 BMP 图像数据
void read_bmp_data(FILE *fp, unsigned char *data, int width, int height) {
    int padding = (4 - (width * 3) % 4) % 4;
    unsigned char pixel[3];
    for (int i = 0; i < height; i++) {
        for (int j = 0; j < width; j++) {
            fread(pixel, sizeof(unsigned char), 3, fp);
            data[i * width * 3 + j * 3 + 0] = pixel[2];
            data[i * width * 3 + j * 3 + 1] = pixel[1];
            data[i * width * 3 + j * 3 + 2] = pixel[0];
        }
        fseek(fp, padding, SEEK_CUR);
    }
}

// 缩小图像
void downsample(unsigned char *src, unsigned char *dst, int src_width, int src_height, int dst_width, int dst_height) {
    double scale_x = (double)src_width / dst_width;
    double scale_y = (double)src_height / dst_height;
    for (int i = 0; i < dst_height; i++) {
        for (int j = 0; j < dst_width; j++) {
            int src_x = (int)(scale_x * j);
            int src_y = (int)(scale_y * i);
            dst[i * dst_width * 3 + j * 3 + 0] = src[src_y * src_width * 3 + src_x * 3 + 0];
            dst[i * dst_width * 3 + j * 3 + 1] = src[src_y * src_width * 3 + src_x * 3 + 1];
            dst[i * dst_width * 3 + j * 3 + 2] = src[src_y * src_width * 3 + src_x * 3 + 2];
        }
    }
}

// 生成金字塔
void generate_pyramid(unsigned char *src, unsigned char **dst, int width, int height, int levels) {
    for (int i = 0; i < levels; i++) {
        dst[i] = (unsigned char *)malloc(sizeof(unsigned char) * width * height * 3);
        downsample(src, dst[i], width, height, width / pow(2, i + 1), height / pow(2, i + 1));
        src = dst[i];
    }
}

// 保存 BMP 图像数据
void save_bmp_data(FILE *fp, unsigned char *data, int width, int height) {
    int padding = (4 - (width * 3) % 4) % 4;
    unsigned char pixel[3] = { 0 };
    for (int i = 0; i < height; i++) {
        for (int j = 0; j < width; j++) {
            pixel[2] = data[i * width * 3 + j * 3 + 0];
            pixel[1] = data[i * width * 3 + j * 3 + 1];
            pixel[0] = data[i * width * 3 + j * 3 + 2];
            fwrite(pixel, sizeof(unsigned char), 3, fp);
        }
        for (int j = 0; j < padding; j++) {
            fwrite(&pixel, sizeof(unsigned char), 1, fp);
        }
    }
}

int main(int argc, char *argv[]) {
    if (argc != 3) {
        fprintf(stderr, "Usage: %s <input_file> <output_file>\n", argv[0]);
        return 1;
    }

    FILE *fp_in = fopen(argv[1], "rb");
    if (!fp_in) {
        fprintf(stderr, "Failed to open input file %s\n", argv[1]);
        return 1;
    }

    FILE *fp_out = fopen(argv[2], "wb");
    if (!fp_out) {
        fprintf(stderr, "Failed to open output file %s\n", argv[2]);
        fclose(fp_in);
        return 1;
    }

    int width, height;
    read_bmp_header(fp_in, &width, &height);
    unsigned char *data = (unsigned char *)malloc(sizeof(unsigned char) * width * height * 3);
    read_bmp_data(fp_in, data, width, height);

    unsigned char *pyramid[MAX_LEVELS];
    generate_pyramid(data, pyramid, width, height, MAX_LEVELS);

    for (int i = 0; i < MAX_LEVELS; i++) {
        save_bmp_data(fp_out, pyramid[i], width / pow(2, i), height / pow(2, i));
    }

    fclose(fp_in);
    fclose(fp_out);
    free(data);
    for (int i = 0; i < MAX_LEVELS; i++) {
        free(pyramid[i]);
    }

    return 0;
}

注：本代码仅供参考，具体实现可能需要根据实际需求进行修改。