c语言完成，直接写代码，不用解释：编写程序完成BMP图像(真彩色、256色)反色处理等功能。

### 回答1：
BMP图像的真彩色反色处理的代码如下：

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

#pragma pack(1)

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

typedef struct {
    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;
} BmpInfoHeader;

typedef struct {
    unsigned char blue;
    unsigned char green;
    unsigned char red;
} RgbTriple;

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

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

    BmpFileHeader fileHeader;
    BmpInfoHeader infoHeader;
    fread(&fileHeader, sizeof(BmpFileHeader), 1, fin);
    fread(&infoHeader, sizeof(BmpInfoHeader), 1, fin);

    if (fileHeader.bfType != 0x4d42) {
        printf("Error: input file is not a BMP file.\n");
        fclose(fin);
        return 1;
    }

    if (infoHeader.biBitCount != 24) {
        printf("Error: input file is not a true color BMP file.\n");
        fclose(fin);
        return 1;
    }

    int rowSize = (infoHeader.biWidth * infoHeader.biBitCount + 31) / 32 * 4;
    int padding = rowSize - infoHeader.biWidth * infoHeader.biBitCount / 8;
    int imageSize = rowSize * abs(infoHeader.biHeight);

    RgbTriple *imageData = (RgbTriple *)malloc(imageSize);
    if (imageData == NULL) {
        printf("Error: failed to allocate memory.\n");
        fclose(fin);
        return 1;
    }

    fseek(fin, fileHeader.bfOffBits, SEEK_SET);
    fread(imageData, imageSize, 1, fin);
    fclose(fin);

    for (int i = 0; i < imageSize; i += 3) {
        imageData[i / 3].blue = 255 - imageData[i / 3].blue;
        imageData[i / 3].green = 255 - imageData[i / 3].green;
  

### 回答2：
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct {
    unsigned char blue;
    unsigned char green;
    unsigned char red;
} Pixel;

typedef struct {
    int width;
    int height;
    Pixel **pixels;
} BMPImage;

BMPImage* readBMPImage(char* filename) {
    FILE* file = fopen(filename, "rb");
    if (file == NULL) {
        printf("Failed to open the file.\n");
        return NULL;
    }

    unsigned char header[54];
    fread(header, sizeof(unsigned char), 54, file);

    int width = *(int*)&header[18];
    int height = *(int*)&header[22];

    int numPixels = width * height;
    int dataSize = numPixels * 3;
    unsigned char* data = (unsigned char*)malloc(dataSize * sizeof(unsigned char));
    fread(data, sizeof(unsigned char), dataSize, file);

    fclose(file);

    BMPImage* image = (BMPImage*)malloc(sizeof(BMPImage));
    image->width = width;
    image->height = height;
    image->pixels = (Pixel**)malloc(height * sizeof(Pixel*));
    for (int i = 0; i < height; i++) {
        image->pixels[i] = (Pixel*)malloc(width * sizeof(Pixel));
        for (int j = 0; j < width; j++) {
            int index = i * width + j;
            image->pixels[i][j].blue = data[index * 3];
            image->pixels[i][j].green = data[index * 3 + 1];
            image->pixels[i][j].red = data[index * 3 + 2];
        }
    }

    free(data);
    return image;
}

void invertBMPImage(BMPImage* image) {
    for (int i = 0; i < image->height; i++) {
        for (int j = 0; j < image->width; j++) {
            image->pixels[i][j].blue = 255 - image->pixels[i][j].blue;
            image->pixels[i][j].green = 255 - image->pixels[i][j].green;
            image->pixels[i][j].red = 255 - image->pixels[i][j].red;
        }
    }
}

void saveBMPImage(BMPImage* image, char* filename) {
    FILE* file = fopen(filename, "wb");
    if (file == NULL) {
        printf("Failed to create the file.\n");
        return;
    }

    unsigned char header[54] = {
        0x42, 0x4D, 0x38, 0x6C, 0x07, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x36, 0x00, 0x00, 0x00, 0x28, 0x00,
        0x00, 0x00, 0x64, 0x00, 0x00, 0x00, 0x58, 0xFB,
        0xFF, 0xFF, 0x01, 0x00, 0x18, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x6C, 0x07, 0x00, 0x00, 0x12,
        0x0B, 0x00, 0x00, 0x12, 0x0B, 0x00, 0x00, 0x00,
        0x00, 0x00, 0x00, 0x00, 0x00, 0x00
    };
    *(int*)&header[2] = 54 + image->width * image->height * 3;
    *(int*)&header[18] = image->width;
    *(int*)&header[22] = image->height;
    fwrite(header, sizeof(unsigned char), 54, file);

    for (int i = 0; i < image->height; i++) {
        for (int j = 0; j < image->width; j++) {
            fwrite(&image->pixels[i][j].blue, sizeof(unsigned char), 1, file);
            fwrite(&image->pixels[i][j].green, sizeof(unsigned char), 1, file);
            fwrite(&image->pixels[i][j].red, sizeof(unsigned char), 1, file);
        }
    }

    fclose(file);
}

int main() {
    BMPImage* image = readBMPImage("input.bmp");
    invertBMPImage(image);
    saveBMPImage(image, "output.bmp");

    for (int i = 0; i < image->height; i++) {
        free(image->pixels[i]);
    }
    free(image->pixels);
    free(image);

    return 0;
}  

### 回答3：
#include <stdio.h>
#include <stdlib.h>

#pragma pack(push) // 保存对齐状态
#pragma pack(2)    // 设定对齐字节为2

// BMP文件头
typedef struct
{
    unsigned short bfType;        // 文件类型，必须为BM
    unsigned int bfSize;          // 文件大小，单位为字节
    unsigned short bfReserved1;   // 保留字段，必须为0
    unsigned short bfReserved2;   // 保留字段，必须为0
    unsigned int bfOffBits;       // 从文件头到像素数据的偏移量
} BMPFileHeader;

// BMP信息头
typedef struct
{
    unsigned int biSize;          // 信息头大小，必须为40
    unsigned int biWidth;         // 图像宽度，单位为像素
    unsigned int biHeight;        // 图像高度，单位为像素
    unsigned short biPlanes;      // 目标设备的平面数，必须为1
    unsigned short biBitCount;    // 每个像素的位数，支持24位和8位
    unsigned int biCompression;   // 压缩类型，必须为0
    unsigned int biSizeImage;     // 图像大小，单位为字节
    unsigned int biXPelsPerMeter; // 水平分辨率，单位为像素每米
    unsigned int biYPelsPerMeter; // 垂直分辨率，单位为像素每米
    unsigned int biClrUsed;       // 实际使用的颜色表中的颜色数
    unsigned int biClrImportant;  // 对图像显示有重要影响的索引数
} BMPInfoHeader;

#pragma pack(pop) // 恢复对齐状态

// 反色处理
void invertColors(unsigned char* imageData, unsigned int imageSize)
{
    for (unsigned int i = 0; i < imageSize; i++)
    {
        imageData[i] = ~imageData[i];
    }
}

int main()
{
    FILE* file = fopen("input.bmp", "rb"); // 打开BMP文件

    if (file == NULL)
    {
        printf("文件打开失败。\n");
        return 0;
    }

    BMPFileHeader fileHeader;
    BMPInfoHeader infoHeader;

    fread(&fileHeader, sizeof(BMPFileHeader), 1, file); // 读取文件头
    fread(&infoHeader, sizeof(BMPInfoHeader), 1, file); // 读取信息头

    unsigned int imageSize = infoHeader.biSizeImage;
    unsigned char* imageData = (unsigned char*)malloc(imageSize); // 分配内存

    fread(imageData, sizeof(unsigned char), imageSize, file); // 读取图像数据

    fclose(file); // 关闭文件

    invertColors(imageData, imageSize); // 反色处理

    file = fopen("output.bmp", "wb"); // 创建输出BMP文件

    if (file == NULL)
    {
        printf("文件创建失败。\n");
        free(imageData);
        return 0;
    }

    fwrite(&fileHeader, sizeof(BMPFileHeader), 1, file); // 写入文件头
    fwrite(&infoHeader, sizeof(BMPInfoHeader), 1, file); // 写入信息头
    fwrite(imageData, sizeof(unsigned char), imageSize, file); // 写入图像数据

    fclose(file); // 关闭文件
    free(imageData); // 释放内存

    printf("图像处理完成。\n");

    return 0;
}