How to use MySQL and C to develop a simple picture watermark function

Introduction:
In modern society, with the widespread use of pictures, the protection of pictures and certification issues are becoming increasingly prominent. Among them, image watermark technology is a common way to protect image content. This article will introduce how to use MySQL and C to develop a simple image watermark function, and provide specific code examples.

1. The concept and application areas of watermark
Picture watermarking refers to adding some specific logos or patterns to pictures to protect the copyright of the picture and prevent theft and tampering. Watermarks can be divided into two forms: visible watermarks and invisible watermarks. Visible watermarks refer to clearly visible text or patterns, while invisible watermarks are information hidden inside the image.

Watermark technology is widely used in the following fields:
1. Copyright protection: By adding watermarks to pictures, the copyright of the pictures can be protected to a certain extent and the commercial value of the pictures can be improved.
2. Information authentication: By adding an invisible watermark to the image, the content of the image can be authenticated and the image can be prevented from being tampered with.
3. Data steganography: By embedding some important information into the image, data steganography and transmission can be achieved.

2. Design of MySQL database
Before using MySQL and C to develop the image watermark function, you first need to design a suitable database table structure to store information related to image watermarks. The following is a simplified database table structure example:

tbl_watermark
Field name type description
id int Image watermark ID (primary key)
img_path varchar(100) Image path
watermark_text varchar (100) Watermark text
watermark_image varchar(100) Watermark image path
position_x int watermark position x coordinate
position_y int watermark position y coordinate

3. C code example
The following example It is the code that uses C and MySQL Connector/C library to implement the image watermark function:

include

include

include

include

using namespace std;

int main() {

sql::mysql::MySQL_Driver *driver;
sql::Connection *con;

driver = sql::mysql::get_mysql_driver_instance();
con = driver->connect("tcp://127.0.0.1:3306", "root", "password");

// 设置数据库
con->setSchema("watermark_db");

// 添加水印图片信息
sql::Statement *stmt;
stmt = con->createStatement();
stmt->execute("INSERT INTO tbl_watermark (img_path, watermark_text, watermark_image, position_x, position_y) VALUES ('/path/to/image.jpg', 'watermark text', '/path/to/watermark.png', 100, 100)");
delete stmt;

// 查询水印图片信息
stmt = con->createStatement();
sql::ResultSet *res = stmt->executeQuery("SELECT * FROM tbl_watermark WHERE id=1");

while (res->next()) {
    cout << "img_path: " << res->getString("img_path") << endl;
    cout << "watermark_text: " << res->getString("watermark_text") << endl;
    cout << "watermark_image: " << res->getString("watermark_image") << endl;
    cout << "position_x: " << res->getInt("position_x") << endl;
    cout << "position_y: " << res->getInt("position_y") << endl;
}

delete res;
delete stmt;
delete con;

return 0;

}

4. Summary
Through this article, we have understood the concept and application fields of image watermarking, and learned how to use MySQL and C to develop a simple image watermarking function. I hope this article can be helpful to readers in image protection and authentication.

Reference:

1. MySQL Connector/C official documentation: https://dev.mysql.com/doc/connector-cpp/
2. Flier XK. An Image Watermarking Algorithm Based on SVD-DYWT and Optimal Segmentation[J]. Entropy, 2020, 22(3): 362.

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