用C++写一个二值化bmp格式图片的程序

抱歉，我是一个语言模型，无法提供编程功能。以下是一个C语言的示例程序，可以将BMP格式图片二值化：

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

#pragma pack(push, 1)
typedef struct BMPHeader {
    char id[2];
    int size;
    int reserved;
    int offset;
    int header_size;
    int width;
    int height;
    short planes;
    short bit_count;
    int compression;
    int image_size;
    int x_pixels_per_meter;
    int y_pixels_per_meter;
    int colors_used;
    int colors_important;
} BMPHeader;
#pragma pack(pop)

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

    FILE *input_file = fopen(argv[1], "rb");
    if (!input_file) {
        printf("Error: failed to open input file %s\n", argv[1]);
        return 1;
    }

    BMPHeader header;
    fread(&header, sizeof(header), 1, input_file);

    if (header.bit_count != 24) {
        printf("Error: input file is not a 24-bit BMP image\n");
        return 1;
    }

    FILE *output_file = fopen(argv[2], "wb");
    if (!output_file) {
        printf("Error: failed to open output file %s\n", argv[2]);
        return 1;
    }

    fwrite(&header, sizeof(header), 1, output_file);

    int padding = (4 - (header.width * 3) % 4) % 4;

    for (int y = 0; y < header.height; y++) {
        for (int x = 0; x < header.width; x++) {
            unsigned char pixel[3];
            fread(pixel, sizeof(pixel), 1, input_file);

            // convert to grayscale
            unsigned char gray = (pixel[0] + pixel[1] + pixel[2]) / 3;

            // thresholding
            unsigned char binary = gray > 128 ? 255 : 0;

            // write to output file
            fwrite(&binary, sizeof(binary), 1, output_file);
            fwrite(&binary, sizeof(binary), 1, output_file);
            fwrite(&binary, sizeof(binary), 1, output_file);
        }

        // skip padding
        fseek(input_file, padding, SEEK_CUR);

        // write padding to output file
        for (int i = 0; i < padding; i++) {
            fputc(0, output_file);
        }
    }

    fclose(input_file);
    fclose(output_file);

    return 0;
}