单色位图均值滤波C++代码实现

以下是单色位图均值滤波的C代码实现：

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

#define BMP_HEADER_SIZE 54
#define PIXEL_OFFSET 10
#define BITS_PER_PIXEL_OFFSET 28

int width;
int height;
int padding;
unsigned char* bmp_data;

void read_bmp(char* filename) {
    FILE* file = fopen(filename, "rb");
    if (!file) {
        printf("Error: File not found\n");
        exit(1);
    }

    unsigned char header[BMP_HEADER_SIZE];
    fread(header, sizeof(unsigned char), BMP_HEADER_SIZE, file);

    width = *(int*)&header[18];
    height = *(int*)&header[22];
    padding = (4 - (width * 3) % 4) % 4;

    bmp_data = (unsigned char*)malloc(sizeof(unsigned char) * (height * width * 3 + height * padding));
    fseek(file, PIXEL_OFFSET, SEEK_SET);
    fread(bmp_data, sizeof(unsigned char), height * width * 3 + height * padding, file);

    fclose(file);
}

void write_bmp(char* filename, unsigned char* data) {
    FILE* file = fopen(filename, "wb");
    if (!file) {
        printf("Error: Cannot write to file\n");
        exit(1);
    }

    unsigned char header[BMP_HEADER_SIZE];
    memset(header, 0, BMP_HEADER_SIZE);
    header[0] = 'B';
    header[1] = 'M';
    *(int*)&header[2] = BMP_HEADER_SIZE + width * height * 3 + height * padding;
    header[10] = BMP_HEADER_SIZE;
    *(int*)&header[18] = width;
    *(int*)&header[22] = height;
    header[26] = 1;
    header[28] = 24;

    fwrite(header, sizeof(unsigned char), BMP_HEADER_SIZE, file);
    fwrite(data, sizeof(unsigned char), height * width * 3 + height * padding, file);

    fclose(file);
}

void apply_filter(unsigned char* data) {
    unsigned char* temp_data = (unsigned char*)malloc(sizeof(unsigned char) * (height * width * 3 + height * padding));
    memcpy(temp_data, data, sizeof(unsigned char) * (height * width * 3 + height * padding));

    for (int i = 1; i < height - 1; i++) {
        for (int j = 1; j < width - 1; j++) {
            int sum_r = 0, sum_g = 0, sum_b = 0;
            for (int k = -1; k <= 1; k++) {
                for (int l = -1; l <= 1; l++) {
                    sum_r += temp_data[((i + k) * width + (j + l)) * 3 + 2];
                    sum_g += temp_data[((i + k) * width + (j + l)) * 3 + 1];
                    sum_b += temp_data[((i + k) * width + (j + l)) * 3];
                }
            }
            data[(i * width + j) * 3 + 2] = sum_r / 9;
            data[(i * width + j) * 3 + 1] = sum_g / 9;
            data[(i * width + j) * 3] = sum_b / 9;
        }
    }

    free(temp_data);
}

int main() {
    read_bmp("input.bmp");
    apply_filter(bmp_data);
    write_bmp("output.bmp", bmp_data);
    free(bmp_data);
    return 0;
}