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车牌识别 ​

识别车辆的车牌信息和位置

概述 ​

车牌识别API是一个用于识别车辆车牌的Web服务。它提供了一种简单而强大的方式来自动识别图像中的车牌号码。无论是在停车场管理、交通监控、智能停车系统还是其他与车辆识别相关的应用中，该API都可以帮助您快速准确地提取车牌信息。

通过车牌识别API，您只需将包含车牌的图像发送到服务器，API将返回识别结果，包括车牌号码、置信度等信息。这使得您可以轻松地集成车牌识别功能到自己的应用程序中，无需进行复杂的图像处理和模式识别算法的开发。

API访问点 ​

  • URL: https://mono-backend.sihe.cloud/api/ai_service/v1/license_plate_recognition
  • 请求方法: POST

AK/SK ​

将API集成到项目中之前，您首先需要在平台中创建属于自己账户的AccessKey ID 和 AccessKey Secret，用于API调用的授权。创建方式详见下图。 ak-sk管理.jpg

请求头 ​

json
{"Content-Type": xxxx, "Accept": "application/json", "Authorization": xxxx}
// 其中ContentType和Authorization的获取请参考下方代码示例
{"Content-Type": xxxx, "Accept": "application/json", "Authorization": xxxx}
// 其中ContentType和Authorization的获取请参考下方代码示例

请求参数 ​

请求参数应该以multipart/form-data格式在请求中发送。

参数名类型必需描述
img_url字符串否车牌图片地址链接
img_fileFile否车牌图片文件（与链接二选一）

响应 ​

API的响应以JSON格式返回。

响应内容说明

Key类型描述
plate_no字符串车牌号码
landmarks列表车牌位置的四个点的坐标
score数值置信度得分（0-1之间）

成功响应示例

json
{
    "result": [
        {
            "plate_no": "沪KR9888",
            "landmarks": [
                [
                    235.0,
                    312.0
                ],
                [
                    467.0,
                    312.0
                ],
                [
                    464.0,
                    378.0
                ],
                [
                    235.0,
                    379.0
                ]
            ],
            "score": 0.913654625415802
        }
    ]
}
{
    "result": [
        {
            "plate_no": "沪KR9888",
            "landmarks": [
                [
                    235.0,
                    312.0
                ],
                [
                    467.0,
                    312.0
                ],
                [
                    464.0,
                    378.0
                ],
                [
                    235.0,
                    379.0
                ]
            ],
            "score": 0.913654625415802
        }
    ]
}

代码示例 ​

Python示例

python
import requests
import hashlib
import hmac
import base64
from requests_toolbelt import MultipartEncoder

# 此处替换为您的AccessKey信息
ak = 'xxxxxxx'
sk = 'xxxxxxxxxxxxxxxx'


class SignClient:
    @staticmethod
    def _get_canonicalized_headers(headers):
        canon_keys = []
        for k in headers:
            if k.startswith('x-acs-'):
                canon_keys.append(k)
        canon_keys = sorted(canon_keys)
        canon_header = ''
        for k in canon_keys:
            canon_header += '%s:%s' % (k, headers[k])
        return canon_header

    @staticmethod
    def _get_canonicalized_resource(pathname, query):
        if len(query) <= 0:
            return pathname
        resource = '%s?' % pathname
        query_list = sorted(list(query))
        for key in query_list:
            if query[key] is not None:
                if query[key] == '':
                    s = '%s&' % key
                else:
                    s = '%s=%s&' % (key, query[key])
                resource += s
        return resource[:-1]

    @staticmethod
    def get_string_to_sign(request, path):
        """
        Get the string to be signed according to request
        @param request  which contains signed messages
        @return the signed string
        """
        method, pathname, headers, query = request.method, path, request.headers, request.params

        accept = '' if headers.get('Accept') is None else headers.get('Accept')
        content_md5 = '' if headers.get('Content-MD5') is None else headers.get('Content-MD5')
        content_type = '' if headers.get('Content-Type') is None else headers.get('Content-Type')
        date = '' if headers.get('Date') is None else headers.get('Date')

        header = '%s\n%s\n%s\n%s\n%s\n' % (method, accept, content_md5, content_type, date)
        canon_headers = SignClient._get_canonicalized_headers(headers)
        canon_resource = SignClient._get_canonicalized_resource(pathname, query)
        sign_str = header + canon_headers + canon_resource
        return sign_str

    @staticmethod
    def get_signature(sign, secret):
        """
        Get signature according to stringToSign, secret
        @param sign the signed string
        @param secret accesskey secret
        @return the signature
        """
        hash_val = hmac.new(secret.encode('utf-8'), sign.encode('utf-8'), hashlib.sha1).digest()
        signature = base64.b64encode(hash_val).decode('utf-8')
        return signature


if __name__ == '__main__':

    url = "https://mono-backend.sihe.cloud"
    pathname = '/api/ai_service/v1/license_plate_recognition'

    data = MultipartEncoder(
        fields={
            'img_url': 'https://img2.baidu.com/it/u=2451098355,3223916536&fm=253&fmt=auto&app=138&f=JPEG?w=682&h=500'
        }
    )
    # data = MultipartEncoder(
    #     fields={
    #         'img_file': ('20230707-223601.png', open('C:\Users\gousq\Desktop\20230707-223601.png', 'rb'), 'image/jpeg')
    #     }
    # )

    header = {"Content-Type": data.content_type, "Accept": "application/json"}

    # 图片地址和文件二选一
    request = requests.Request('POST', url + pathname, headers=header, data=data)

    signToString = SignClient.get_string_to_sign(request, pathname)
    sign = SignClient.get_signature(signToString, sk)
    request.headers['Authorization'] = 'acs ' + ak + ':' + sign

    # 发送请求
    s = requests.Session()
    response = s.send(request.prepare(), timeout=10)
    print(response.text)
import requests
import hashlib
import hmac
import base64
from requests_toolbelt import MultipartEncoder

# 此处替换为您的AccessKey信息
ak = 'xxxxxxx'
sk = 'xxxxxxxxxxxxxxxx'


class SignClient:
    @staticmethod
    def _get_canonicalized_headers(headers):
        canon_keys = []
        for k in headers:
            if k.startswith('x-acs-'):
                canon_keys.append(k)
        canon_keys = sorted(canon_keys)
        canon_header = ''
        for k in canon_keys:
            canon_header += '%s:%s' % (k, headers[k])
        return canon_header

    @staticmethod
    def _get_canonicalized_resource(pathname, query):
        if len(query) <= 0:
            return pathname
        resource = '%s?' % pathname
        query_list = sorted(list(query))
        for key in query_list:
            if query[key] is not None:
                if query[key] == '':
                    s = '%s&' % key
                else:
                    s = '%s=%s&' % (key, query[key])
                resource += s
        return resource[:-1]

    @staticmethod
    def get_string_to_sign(request, path):
        """
        Get the string to be signed according to request
        @param request  which contains signed messages
        @return the signed string
        """
        method, pathname, headers, query = request.method, path, request.headers, request.params

        accept = '' if headers.get('Accept') is None else headers.get('Accept')
        content_md5 = '' if headers.get('Content-MD5') is None else headers.get('Content-MD5')
        content_type = '' if headers.get('Content-Type') is None else headers.get('Content-Type')
        date = '' if headers.get('Date') is None else headers.get('Date')

        header = '%s\n%s\n%s\n%s\n%s\n' % (method, accept, content_md5, content_type, date)
        canon_headers = SignClient._get_canonicalized_headers(headers)
        canon_resource = SignClient._get_canonicalized_resource(pathname, query)
        sign_str = header + canon_headers + canon_resource
        return sign_str

    @staticmethod
    def get_signature(sign, secret):
        """
        Get signature according to stringToSign, secret
        @param sign the signed string
        @param secret accesskey secret
        @return the signature
        """
        hash_val = hmac.new(secret.encode('utf-8'), sign.encode('utf-8'), hashlib.sha1).digest()
        signature = base64.b64encode(hash_val).decode('utf-8')
        return signature


if __name__ == '__main__':

    url = "https://mono-backend.sihe.cloud"
    pathname = '/api/ai_service/v1/license_plate_recognition'

    data = MultipartEncoder(
        fields={
            'img_url': 'https://img2.baidu.com/it/u=2451098355,3223916536&fm=253&fmt=auto&app=138&f=JPEG?w=682&h=500'
        }
    )
    # data = MultipartEncoder(
    #     fields={
    #         'img_file': ('20230707-223601.png', open('C:\Users\gousq\Desktop\20230707-223601.png', 'rb'), 'image/jpeg')
    #     }
    # )

    header = {"Content-Type": data.content_type, "Accept": "application/json"}

    # 图片地址和文件二选一
    request = requests.Request('POST', url + pathname, headers=header, data=data)

    signToString = SignClient.get_string_to_sign(request, pathname)
    sign = SignClient.get_signature(signToString, sk)
    request.headers['Authorization'] = 'acs ' + ak + ':' + sign

    # 发送请求
    s = requests.Session()
    response = s.send(request.prepare(), timeout=10)
    print(response.text)

JAVA示例

JAVA
//依赖库
//<dependency>
//    <groupId>com.aliyun</groupId>
//    <artifactId>aliyun-java-sdk-core</artifactId>
//    <version>4.5.20</version>
//</dependency>
//<dependency>
//    <groupId>com.squareup.okhttp3</groupId>
//    <artifactId>okhttp</artifactId>
//    <!-- MinIO requires a higher version -->
//    <version>4.8.1</version>
//</dependency>

import com.aliyuncs.auth.HmacSHA1Signer;
import com.aliyuncs.auth.RoaSignatureComposer;
import com.aliyuncs.auth.Signer;
import com.aliyuncs.http.MethodType;
import kotlin.Pair;
import okhttp3.*;

import java.io.File;
import java.util.HashMap;
import java.util.Map;
import java.util.TreeMap;

public class JavaDemo {

    //请替换成您的AccessKeyId和AccessKeySecret
    static final String accessKeyId = "xxxxxxx";
    static final String accessKeySecret = "xxxxxxxxxxxxxxxxxxxx";

    public static void main(String[] args){

        String url = "https://mono-backend.sihe.cloud/api/ai_service/v1/license_plate_recognition";

        // 图片地址和文件二选一
        String img_url = "https://img2.baidu.com/it/u=2451098355,3223916536&fm=253&fmt=auto&app=138&f=JPEG?w=682&h=500";
        File img_file = new File("C:\Users\gousq\Desktop\20230707-223601.png");

        try {

            OkHttpClient client = new OkHttpClient().newBuilder().build();
            RequestBody body = new MultipartBody.Builder().setType(MultipartBody.FORM)
                    .addFormDataPart("img_url",img_url)
//                    .addFormDataPart("img_file",img_file.getName(),
//                            RequestBody.create(MediaType.parse("application/octet-stream"),
//                                    img_file))
                    .build();

            Request request = new Request.Builder()
                    .url(url)
                    .method("POST", body)
                    .addHeader("Content-Type", body.contentType().toString())
                    .addHeader("Accept", "application/json")
                    .build();

            String sign = sign(request);
            request = request.newBuilder().addHeader("Authorization", "acs " + accessKeyId + ":" + sign).build();

            Response response = client.newCall(request).execute();
            System.out.println(response.body().string());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private static String sign(Request request) {
        Signer signer = new HmacSHA1Signer();
        RoaSignatureComposer composer = new RoaSignatureComposer();
        //提取headers的map
        Map<String, String> headers = new TreeMap<>();
        for (Pair<? extends String, ? extends String> header : request.headers()) {
            headers.put(header.getFirst(), header.getSecond());
        }
        String stringToSign = composer.composeStringToSign(MethodType.valueOf(request.method()), request.url().encodedPath(), signer,
                new HashMap<>(),headers, new HashMap<>());
        return signer.signString(stringToSign, accessKeySecret);
    }
}
//依赖库
//<dependency>
//    <groupId>com.aliyun</groupId>
//    <artifactId>aliyun-java-sdk-core</artifactId>
//    <version>4.5.20</version>
//</dependency>
//<dependency>
//    <groupId>com.squareup.okhttp3</groupId>
//    <artifactId>okhttp</artifactId>
//    <!-- MinIO requires a higher version -->
//    <version>4.8.1</version>
//</dependency>

import com.aliyuncs.auth.HmacSHA1Signer;
import com.aliyuncs.auth.RoaSignatureComposer;
import com.aliyuncs.auth.Signer;
import com.aliyuncs.http.MethodType;
import kotlin.Pair;
import okhttp3.*;

import java.io.File;
import java.util.HashMap;
import java.util.Map;
import java.util.TreeMap;

public class JavaDemo {

    //请替换成您的AccessKeyId和AccessKeySecret
    static final String accessKeyId = "xxxxxxx";
    static final String accessKeySecret = "xxxxxxxxxxxxxxxxxxxx";

    public static void main(String[] args){

        String url = "https://mono-backend.sihe.cloud/api/ai_service/v1/license_plate_recognition";

        // 图片地址和文件二选一
        String img_url = "https://img2.baidu.com/it/u=2451098355,3223916536&fm=253&fmt=auto&app=138&f=JPEG?w=682&h=500";
        File img_file = new File("C:\Users\gousq\Desktop\20230707-223601.png");

        try {

            OkHttpClient client = new OkHttpClient().newBuilder().build();
            RequestBody body = new MultipartBody.Builder().setType(MultipartBody.FORM)
                    .addFormDataPart("img_url",img_url)
//                    .addFormDataPart("img_file",img_file.getName(),
//                            RequestBody.create(MediaType.parse("application/octet-stream"),
//                                    img_file))
                    .build();

            Request request = new Request.Builder()
                    .url(url)
                    .method("POST", body)
                    .addHeader("Content-Type", body.contentType().toString())
                    .addHeader("Accept", "application/json")
                    .build();

            String sign = sign(request);
            request = request.newBuilder().addHeader("Authorization", "acs " + accessKeyId + ":" + sign).build();

            Response response = client.newCall(request).execute();
            System.out.println(response.body().string());
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    private static String sign(Request request) {
        Signer signer = new HmacSHA1Signer();
        RoaSignatureComposer composer = new RoaSignatureComposer();
        //提取headers的map
        Map<String, String> headers = new TreeMap<>();
        for (Pair<? extends String, ? extends String> header : request.headers()) {
            headers.put(header.getFirst(), header.getSecond());
        }
        String stringToSign = composer.composeStringToSign(MethodType.valueOf(request.method()), request.url().encodedPath(), signer,
                new HashMap<>(),headers, new HashMap<>());
        return signer.signString(stringToSign, accessKeySecret);
    }
}