写一段代码画出一个图像的灰度直方图（不能用MATLAB自带的imhist函数），并作直方图均衡化处理。

以下是一段画出图像灰度直方图并进行直方图均衡化处理的代码：

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

#define WIDTH 256
#define HEIGHT 256

int main()
{
    FILE *fp;
    unsigned char image[WIDTH][HEIGHT];
    int hist[WIDTH] = {};
    int cdf[WIDTH] = {};
    int min_cdf = WIDTH * HEIGHT;
    int i, j;

    // 读取图像
    fp = fopen("lena.raw", "rb");
    fread(image, sizeof(unsigned char), WIDTH * HEIGHT, fp);
    fclose(fp);

    // 计算灰度直方图
    for (i = ; i < WIDTH; i++) {
        for (j = ; j < HEIGHT; j++) {
            hist[image[i][j]]++;
        }
    }

    // 计算累积分布函数
    for (i = ; i < WIDTH; i++) {
        if (i == ) {
            cdf[i] = hist[i];
        } else {
            cdf[i] = cdf[i - 1] + hist[i];
        }
        if (cdf[i] < min_cdf && hist[i] > ) {
            min_cdf = cdf[i];
        }
    }

    // 直方图均衡化
    for (i = ; i < WIDTH; i++) {
        for (j = ; j < HEIGHT; j++) {
            image[i][j] = (unsigned char)((cdf[image[i][j]] - min_cdf) * 255. / (WIDTH * HEIGHT - min_cdf));
        }
    }

    // 输出均衡化后的图像和直方图
    fp = fopen("lena_eq.raw", "wb");
    fwrite(image, sizeof(unsigned char), WIDTH * HEIGHT, fp);
    fclose(fp);

    fp = fopen("hist.txt", "w");
    for (i = ; i < WIDTH; i++) {
        fprintf(fp, "%d\n", hist[i]);
    }
    fclose(fp);

    return ;
}

这段代码读取名为"lena.raw"的灰度图像，计算出其灰度直方图，并进行直方图均衡化处理，最终输出均衡化后的图像和直方图。