A Beginner’s Guide to Face Recognition in PHP

With the continuous development of technology, face recognition technology has become more and more widely used. In the field of web development, PHP is a widely adopted technology, so the face recognition technology in PHP has also attracted much attention. This article will introduce the introductory guide to face recognition in PHP to help beginners quickly master this field.

1. What is face recognition technology

Face recognition technology is a biometric identification technology based on computer vision technology. Its main application areas include security, finance, e-commerce, etc. The core of face recognition technology is to recognize faces and match face images with identity information.

2. Face recognition technology in PHP

Face recognition technology in PHP is mainly implemented by calling third-party APIs. In PHP, calling these APIs requires communication with the HTTP protocol.

1. Call API

When using PHP for face recognition, we need to call a third-party API for face detection and recognition. Commonly used APIs include Face, Baidu AI face recognition, etc. Here we take Face as an example.

To call Face's API, you need to first register an account, create an application, and then obtain the API key and secret. In PHP, the API is called through the curl function.

Sample code:

$api_key = "your api_key";
$api_secret = "your api_secret";
$image_file = "test.jpg";

$ch = curl_init();
curl_setopt($ch, CURLOPT_URL, "https://api-cn.faceplusplus.com/facepp/v3/detect");
curl_setopt($ch, CURLOPT_HEADER, 0);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
curl_setopt($ch, CURLOPT_POST, 1);
curl_setopt($ch, CURLOPT_POSTFIELDS, [
    "api_key" => $api_key,
    "api_secret" => $api_secret,
    "image_file" => new CURLFile($image_file),
    "return_attributes" => "gender,age"
]);
$result = curl_exec($ch);
curl_close($ch);

echo $result;

In the above code, we use the curl library to call Face's face detection API, upload the image and specify the attributes to be returned as gender and age.

2. Parse the results returned by the API

After calling the API, we need to parse the results returned by the API. In Face, the returned results are in JSON format. We need to parse according to the format specified in the API document.

Sample code:

$result = json_decode($result, true);
if($result && isset($result["faces"])) {
    foreach($result["faces"] as $face) {
        print_r($face["attributes"]);
    }
}

In the above code, we use the json_decode function to convert the JSON string returned by the API into an array. Then we traverse the faces in the array and obtain the attribute information of the face.

3. Face recognition application in PHP

In PHP, face recognition technology can be applied to many scenarios, such as face login, face payment, face check-in, etc. Here we take face login as an example.

1. Face verification

During the face login process, we need to implement the face verification function. There are two methods to achieve face verification: comparing feature values ​​and comparing face images.

Comparing feature values ​​means converting face images into corresponding feature values, and then verifying them by comparing feature values. Commonly used facial feature value representation methods include PCA, LBP, etc. Comparing face images refers to directly comparing face images. If the similarity between the two images reaches a certain threshold, the verification is considered passed.

2. Face entry

During the face login process, we also need to implement the face entry function. The method of face entry is to process the face image uploaded by the user, extract the corresponding feature values ​​and save it in the database.

Sample code:

//提取人脸特征值
function extract_feature($image_file) {
    $api_key = "your api_key";
    $api_secret = "your api_secret";

    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, "https://api-cn.faceplusplus.com/facepp/v3/face/analyze");
    curl_setopt($ch, CURLOPT_HEADER, 0);
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($ch, CURLOPT_POST, 1);
    curl_setopt($ch, CURLOPT_POSTFIELDS, [
        "api_key" => $api_key,
        "api_secret" => $api_secret,
        "image_file" => new CURLFile($image_file),
        "return_landmark" => 1,
        "return_attributes" => "gender,age,smiling,headpose,eyestatus,ethnicity,beauty"
    ]);
    $result = curl_exec($ch);
    curl_close($ch);

    $result = json_decode($result, true);
    if($result && isset($result["faces"])) {
        foreach($result["faces"] as $face) {
            return $face["face_token"];
        }
    }
    return null;
}

//保存人脸特征值到数据库中
function save_feature($feature, $user_id) {
    $pdo = new PDO("mysql:host=localhost;dbname=test", "root", "123456");
    $stmt = $pdo->prepare("INSERT INTO face_feature(user_id, feature) VALUES(?, ?)");
    $stmt->bindValue(1, $user_id);
    $stmt->bindValue(2, $feature);
    $stmt->execute();
}

$image_file = "test.jpg";
$user_id = 1;

$feature = extract_feature($image_file);
if($feature) {
    save_feature($feature, $user_id);
}

In the above code, we use Face’s API to extract facial feature values ​​and save the feature values ​​to the database. During the save process, we used the PDO database library to access the database.

Summary

Through the introduction of this article, we can see that face recognition technology in PHP is not difficult to master. By calling third-party APIs and parsing APIs to return results, we can implement face recognition applications. Of course, in addition to Face, there are many other face recognition APIs that can be used. Therefore, if you want to explore face recognition technology in PHP in depth, you must try different APIs to better apply it in actual scenarios.

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