c语言图片添加水印程序,[求助]C语言 bmp文件加上水印

以下是一个简单的 C 语言示例程序，可以将 BMP 文件添加水印：

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

#pragma pack(push, 1)

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

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

#pragma pack(pop)

int main(int argc, char *argv[]) {
    if (argc < 4) {
        printf("Usage: %s input.bmp output.bmp watermark\n", argv[0]);
        return 1;
    }

    char *input_file = argv[1];
    char *output_file = argv[2];
    char *watermark = argv[3];

    FILE *input = fopen(input_file, "rb");
    if (input == NULL) {
        printf("Failed to open input file: %s\n", input_file);
        return 1;
    }

    BITMAPFILEHEADER file_header;
    BITMAPINFOHEADER info_header;

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

    if (file_header.bfType != 0x4D42 || info_header.biBitCount != 24) {
        printf("Invalid BMP file format\n");
        fclose(input);
        return 1;
    }

    int width = info_header.biWidth;
    int height = info_header.biHeight;
    int padding = (4 - ((width * 3) % 4)) % 4;

    char *image_data = (char *) malloc(sizeof(char) * width * height * 3);
    fread(image_data, sizeof(char), width * height * 3, input);

    fclose(input);

    int watermark_length = strlen(watermark);
    int i, j, k;

    for (i = 0; i < width; i++) {
        for (j = 0; j < height; j++) {
            int index = j * width + i;
            int r = image_data[index * 3 + 2];
            int g = image_data[index * 3 + 1];
            int b = image_data[index * 3];

            if (i < watermark_length) {
                char c = watermark[i];
                int value = (int) c;

                for (k = 0; k < 8; k++) {
                    int bit = (value >> (7 - k)) & 1;
                    if (bit == 1) {
                        if (j < height - 10) {
                            image_data[index * 3 + 2] = 255;
                            image_data[index * 3 + 1] = 0;
                            image_data[index * 3] = 0;
                        }
                    }
                    index += width;
                }
            }

            if (j == height - 1 && i == width - 1) {
                printf("Finished adding watermark\n");
            }
        }
    }

    FILE *output = fopen(output_file, "wb");
    if (output == NULL) {
        printf("Failed to create output file: %s\n", output_file);
        free(image_data);
        return 1;
    }

    fwrite(&file_header, sizeof(BITMAPFILEHEADER), 1, output);
    fwrite(&info_header, sizeof(BITMAPINFOHEADER), 1, output);
    fwrite(image_data, sizeof(char), width * height * 3, output);

    fclose(output);
    free(image_data);

    printf("Successfully saved watermarked image to %s\n", output_file);

    return 0;
}

这个程序需要三个参数：输入 BMP 文件名、输出 BMP 文件名和水印字符串。例如，如果要将名为 "input.bmp" 的 BMP 文件添加水印 "Hello, world!" 并保存为 "output.bmp" 文件，则可以执行以下命令：

./watermark input.bmp output.bmp "Hello, world!"

请注意，此程序仅适用于 24 位色深的 BMP 文件。如果 BMP 文件的色深不是 24 位，则需要相应地修改程序。