c语言实现bmp文件的二值化代码

以下是一个简单的C语言实现bmp文件的二值化代码：

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

#pragma pack(2)

typedef struct tagBITMAPFILEHEADER {
    unsigned short bfType;
    unsigned int bfSize;
    unsigned short bfReserved1;
    unsigned short bfReserved2;
    unsigned int bfOffBits;
} BITMAPFILEHEADER;

typedef struct tagBITMAPINFOHEADER {
    unsigned int biSize;
    int biWidth;
    int biHeight;
    unsigned short biPlanes;
    unsigned short biBitCount;
    unsigned int biCompression;
    unsigned int biSizeImage;
    int biXPelsPerMeter;
    int biYPelsPerMeter;
    unsigned int biClrUsed;
    unsigned int biClrImportant;
} BITMAPINFOHEADER;

typedef struct tagRGBQUAD {
    unsigned char rgbBlue;
    unsigned char rgbGreen;
    unsigned char rgbRed;
    unsigned char rgbReserved;
} RGBQUAD;

typedef struct tagBITMAP {
    BITMAPFILEHEADER fileHeader;
    BITMAPINFOHEADER infoHeader;
    RGBQUAD *palette;
    unsigned char *data;
} BITMAP;

void binarize(BITMAP *bmp) {
    int i, j;
    unsigned char *p = bmp->data;
    for (i = 0; i < bmp->infoHeader.biHeight; i++) {
        for (j = 0; j < bmp->infoHeader.biWidth; j++) {
            // 获取像素值
            unsigned char b = *p++;
            unsigned char g = *p++;
            unsigned char r = *p++;
            // 灰度化
            unsigned char gray = (unsigned char)(0.299 * r + 0.587 * g + 0.114 * b);
            // 二值化
            if (gray >= 128) {
                *p++ = 255;
                *p++ = 255;
                *p++ = 255;
            } else {
                *p++ = 0;
                *p++ = 0;
                *p++ = 0;
            }
        }
    }
}

int main(int argc, char *argv[]) {
    if (argc < 2) {
        printf("Usage: %s <bmp_file>\n", argv[0]);
        return 1;
    }
    char *filename = argv[1];
    FILE *fp = fopen(filename, "rb");
    if (!fp) {
        printf("Failed to open file: %s\n", filename);
        return 1;
    }
    BITMAP bmp;
    memset(&bmp, 0, sizeof(BITMAP));
    fread(&bmp.fileHeader, sizeof(BITMAPFILEHEADER), 1, fp);
    fread(&bmp.infoHeader, sizeof(BITMAPINFOHEADER), 1, fp);
    if (bmp.infoHeader.biBitCount < 24) {
        bmp.palette = (RGBQUAD *)malloc(sizeof(RGBQUAD) * (1 << bmp.infoHeader.biBitCount));
        fread(bmp.palette, sizeof(RGBQUAD), 1 << bmp.infoHeader.biBitCount, fp);
    }
    bmp.data = (unsigned char *)malloc(bmp.infoHeader.biSizeImage);
    fread(bmp.data, 1, bmp.infoHeader.biSizeImage, fp);
    fclose(fp);
    binarize(&bmp);
    char *out_filename = "output.bmp";
    fp = fopen(out_filename, "wb");
    if (!fp) {
        printf("Failed to create file: %s\n", out_filename);
        return 1;
    }
    fwrite(&bmp.fileHeader, sizeof(BITMAPFILEHEADER), 1, fp);
    fwrite(&bmp.infoHeader, sizeof(BITMAPINFOHEADER), 1, fp);
    if (bmp.infoHeader.biBitCount < 24) {
        fwrite(bmp.palette, sizeof(RGBQUAD), 1 << bmp.infoHeader.biBitCount, fp);
    }
    fwrite(bmp.data, 1, bmp.infoHeader.biSizeImage, fp);
    fclose(fp);
    free(bmp.palette);
    free(bmp.data);
    return 0;
}

该代码假设输入文件是24位（即每个像素由3个字节组成）的bmp文件，输出文件格式与输入文件相同，二值化算法为简单的阈值分割法。