帮我用c语言设计一个基于图像的数字水印算法，其中包含LSB算法、DFT算法、DCT算法

好的，下面是一个基于图像的数字水印算法，其中包含LSB算法、DFT算法、DCT算法的C语言实现：

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

// LSB算法
void LSB(unsigned char* img, unsigned char* watermark, int watermark_length, int bit_plane){
    int img_size = 512 * 512 * 3;
    int watermark_index = 0;
    unsigned char mask = 1 << bit_plane;
    for(int i = 0; i < img_size; i += 3){
        if(watermark_index < watermark_length){
            img[i] &= ~mask;
            img[i+1] &= ~mask;
            img[i+2] &= ~mask;
            img[i] |= ((watermark[watermark_index] & 0x80) >> (7 - bit_plane));
            img[i+1] |= ((watermark[watermark_index] & 0x40) >> (6 - bit_plane));
            img[i+2] |= ((watermark[watermark_index] & 0x20) >> (5 - bit_plane));
            watermark_index++;
        }
    }
}

// DFT算法
void DFT(float* img, float* watermark, int watermark_length, int bit_plane){
    int img_size = 512 * 512;
    int watermark_index = 0;
    float complex_factor = exp(-2 * M_PI * I / img_size);
    for(int i = 0; i < img_size; i++){
        if(watermark_index < watermark_length){
            float real_part = img[i] * cos(2 * M_PI * i * watermark_index / img_size) - watermark[watermark_index] * sin(2 * M_PI * i * watermark_index / img_size);
            float imag_part = img[i] * sin(2 * M_PI * i * watermark_index / img_size) + watermark[watermark_index] * cos(2 * M_PI * i * watermark_index / img_size);
            img[i] = real_part + imag_part * complex_factor;
            watermark_index++;
        }
    }
}

// DCT算法
void DCT(float* img, float* watermark, int watermark_length, int bit_plane){
    int img_size = 512 * 512;
    int watermark_index = 0;
    for(int i = 0; i < img_size; i++){
        if(watermark_index < watermark_length){
            float cosine_factor = cos((2 * i + 1) * watermark_index * M_PI / (2 * img_size));
            img[i] += watermark[watermark_index] * cosine_factor;
            watermark_index++;
        }
    }
}

int main(){
    // 读入图像和水印
    FILE* img_file = fopen("lena.raw", "rb");
    unsigned char* img = (unsigned char*)malloc(512 * 512 * 3);
    fread(img, sizeof(unsigned char), 512 * 512 * 3, img_file);
    fclose(img_file);

    FILE* watermark_file = fopen("watermark.txt", "r");
    char* watermark_string = (char*)malloc(1000);
    fgets(watermark_string, 1000, watermark_file);
    fclose(watermark_file);

    // 将水印转换为二进制
    int watermark_length = strlen(watermark_string);
    unsigned char* watermark = (unsigned char*)malloc(watermark_length * 8);
    for(int i = 0; i < watermark_length; i++){
        for(int j = 0; j < 8; j++){
            watermark[i * 8 + j] = (watermark_string[i] & (1 << (7 - j))) >> (7 - j);
        }
    }

    // LSB算法
    LSB(img, watermark, watermark_length * 8, 0);

    // DFT算法
    float* img_float = (float*)malloc(512 * 512 * sizeof(float));
    for(int i = 0; i < 512 * 512 * 3; i++){
        img_float[i] = (float)img[i];
    }

    float* watermark_float = (float*)malloc(watermark_length * sizeof(float));
    for(int i = 0; i < watermark_length; i++){
        watermark_float[i] = (float)watermark[i];
    }

    DFT(img_float, watermark_float, watermark_length, 0);

    for(int i = 0; i < 512 * 512 * 3; i++){
        img[i] = (unsigned char)img_float[i];
    }

    // DCT算法
    for(int i = 0; i < 512 * 512 * 3; i++){
        img_float[i] = (float)img[i];
    }

    DCT(img_float, watermark_float, watermark_length, 0);

    for(int i = 0; i < 512 * 512 * 3; i++){
        img[i] = (unsigned char)img_float[i];
    }

    // 保存图像
    FILE* output_file = fopen("watermarked_lena.raw", "wb");
    fwrite(img, sizeof(unsigned char), 512 * 512 * 3, output_file);
    fclose(output_file);

    return 0;
}

上述代码实现了一个基于图像的数字水印算法，其中包含了LSB算法、DFT算法、DCT算法。该程序读入了一张512x512的彩色图像（lena.raw），并将其和一个文本水印（watermark.txt）进行嵌入。水印嵌入过程中，对于LSB算法，程序将水印的每个比特位嵌入到图像的一个特定比特位中；对于DFT算法，程序将水印嵌入到图像的频域中；对于DCT算法，程序将水印嵌入到图像的空间域中。

需要注意的是，上述代码仅为演示用途，实际应用时，可能需要进行更多的参数调整和优化，以达到更好的水印嵌入效果。