C语言实现BMP图像直方图均衡化

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

#pragma pack(2) typedef struct { short bfType; int bfSize; short bfReserved1; short bfReserved2; int bfOffBits; } BITMAPFILEHEADER;

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

typedef struct { unsigned char b; unsigned char g; unsigned char r; } RGB;

int main() { FILE *fp_in = fopen('3.bmp', 'rb'); if (fp_in == NULL) { printf('open file failed!\n'); return 0; }

BITMAPFILEHEADER file_header;
BITMAPINFOHEADER info_header;

fread(&file_header, sizeof(BITMAPFILEHEADER), 1, fp_in);
fread(&info_header, sizeof(BITMAPINFOHEADER), 1, fp_in);

int width = info_header.biWidth;
int height = info_header.biHeight;
int line_byte = (width * 24 + 31) / 32 * 4;

RGB **data = (RGB**)malloc(sizeof(RGB*) * height);
for (int i = 0; i < height; i++) {
    data[i] = (RGB*)malloc(sizeof(RGB) * width);
    fread(data[i], sizeof(RGB), width, fp_in);
    fseek(fp_in, line_byte - width * sizeof(RGB), SEEK_CUR);
}
fclose(fp_in);

// 直方图均衡
int histogram[256] = {0};
for (int i = 0; i < height; i++) {
    for (int j = 0; j < width; j++) {
        histogram[data[i][j].g]++;
    }
}

int equalization[256] = {0};
int sum = 0;
for (int i = 0; i < 256; i++) {
    sum += histogram[i];
    equalization[i] = sum * 255 / (width * height);
}

for (int i = 0; i < height; i++) {
    for (int j = 0; j < width; j++) {
        data[i][j].g = equalization[data[i][j].g];
    }
}

// 写入文件
FILE *fp_out = fopen('5.bmp', 'wb');
if (fp_out == NULL) {
    printf('create file failed!\n');
    return 0;
}

fwrite(&file_header, sizeof(BITMAPFILEHEADER), 1, fp_out);
fwrite(&info_header, sizeof(BITMAPINFOHEADER), 1, fp_out);

for (int i = 0; i < height; i++) {
    fwrite(data[i], sizeof(RGB), width, fp_out);
    fwrite('\0\0\0\0', 1, line_byte - width * sizeof(RGB), fp_out);
}

fclose(fp_out);

for (int i = 0; i < height; i++) {
    free(data[i]);
}
free(data);

return 0;

}