文字识别

    车牌识别

    接口描述

    支持识别中国大陆机动车蓝牌、黄牌(单双行)、绿牌、大型新能源(黄绿)、领使馆车牌、警牌、武警牌(单双行)、军牌(单双行)、港澳牌、农用车牌、民航车牌的地域编号和车牌号,并能同时识别图像中的多张车牌。

    请求说明

    请求示例

    HTTP 方法: POST

    请求URL: https://aip.baidubce.com/rest/2.0/ocr/v1/license_plate

    URL参数:

    参数
    access_token 通过API Key和Secret Key获取的access_token,参考“Access Token获取

    Header如下:

    参数
    Content-Type application/x-www-form-urlencoded

    Body中放置请求参数,参数详情如下:

    请求参数

    参数 类型 是否必选 说明
    image string true 图像数据,base64编码后进行urlencode,要求base64编码和urlencode后大小不超过4M,最短边至少15px,最长边最大4096px,支持jpg/jpeg/png/bmp格式
    multi_detect boolen false 是否检测多张车牌,默认为false,当置为true的时候可以对一张图片内的多张车牌进行识别

    请求代码示例

    提示一:使用示例代码前,请记得替换其中的示例Token、图片地址或Base64信息。

    提示二:部分语言依赖的类或库,请在代码注释中查看下载地址。

    curl -i -k 'https://aip.baidubce.com/rest/2.0/ocr/v1/license_plate?access_token=【调用鉴权接口获取的token】' --data 'image=【图片Base64编码,需UrlEncode】' -H 'Content-Type:application/x-www-form-urlencoded'
    # encoding:utf-8
    
    import requests
    import base64
    
    '''
    车牌识别
    '''
    
    request_url = "https://aip.baidubce.com/rest/2.0/ocr/v1/license_plate"
    # 二进制方式打开图片文件
    f = open('[本地文件]', 'rb')
    img = base64.b64encode(f.read())
    
    params = {"image":img}
    access_token = '[调用鉴权接口获取的token]'
    request_url = request_url + "?access_token=" + access_token
    headers = {'content-type': 'application/x-www-form-urlencoded'}
    response = requests.post(request_url, data=params, headers=headers)
    if response:
        print (response.json())
    package com.baidu.ai.aip;
    
    import com.baidu.ai.aip.utils.Base64Util;
    import com.baidu.ai.aip.utils.FileUtil;
    import com.baidu.ai.aip.utils.HttpUtil;
    
    import java.net.URLEncoder;
    
    /**
    * 车牌识别
    */
    public class LicensePlate {
    
        /**
        * 重要提示代码中所需工具类
        * FileUtil,Base64Util,HttpUtil,GsonUtils请从
        * https://ai.baidu.com/file/658A35ABAB2D404FBF903F64D47C1F72
        * https://ai.baidu.com/file/C8D81F3301E24D2892968F09AE1AD6E2
        * https://ai.baidu.com/file/544D677F5D4E4F17B4122FBD60DB82B3
        * https://ai.baidu.com/file/470B3ACCA3FE43788B5A963BF0B625F3
        * 下载
        */
        public static String licensePlate() {
            // 请求url
            String url = "https://aip.baidubce.com/rest/2.0/ocr/v1/license_plate";
            try {
                // 本地文件路径
                String filePath = "[本地文件路径]";
                byte[] imgData = FileUtil.readFileByBytes(filePath);
                String imgStr = Base64Util.encode(imgData);
                String imgParam = URLEncoder.encode(imgStr, "UTF-8");
    
                String param = "image=" + imgParam;
    
                // 注意这里仅为了简化编码每一次请求都去获取access_token,线上环境access_token有过期时间, 客户端可自行缓存,过期后重新获取。
                String accessToken = "[调用鉴权接口获取的token]";
    
                String result = HttpUtil.post(url, accessToken, param);
                System.out.println(result);
                return result;
            } catch (Exception e) {
                e.printStackTrace();
            }
            return null;
        }
    
        public static void main(String[] args) {
            LicensePlate.licensePlate();
        }
    }
    #include <iostream>
    #include <curl/curl.h>
    
    // libcurl库下载链接:https://curl.haxx.se/download.html
    // jsoncpp库下载链接:https://github.com/open-source-parsers/jsoncpp/
    const static std::string request_url = "https://aip.baidubce.com/rest/2.0/ocr/v1/license_plate";
    static std::string licensePlate_result;
    /**
    * curl发送http请求调用的回调函数,回调函数中对返回的json格式的body进行了解析,解析结果储存在全局的静态变量当中
    * @param 参数定义见libcurl文档
    * @return 返回值定义见libcurl文档
    */
    static size_t callback(void *ptr, size_t size, size_t nmemb, void *stream) {
        // 获取到的body存放在ptr中,先将其转换为string格式
        licensePlate_result = std::string((char *) ptr, size * nmemb);
        return size * nmemb;
    }
    /**
    * 车牌识别
    * @return 调用成功返回0,发生错误返回其他错误码
    */
    int licensePlate(std::string &json_result, const std::string &access_token) {
        std::string url = request_url + "?access_token=" + access_token;
        CURL *curl = NULL;
        CURLcode result_code;
        int is_success;
        curl = curl_easy_init();
        if (curl) {
            curl_easy_setopt(curl, CURLOPT_URL, url.data());
            curl_easy_setopt(curl, CURLOPT_POST, 1);
            curl_httppost *post = NULL;
            curl_httppost *last = NULL;
            curl_formadd(&post, &last, CURLFORM_COPYNAME, "image", CURLFORM_COPYCONTENTS, "【base64_img】", CURLFORM_END);
    
            curl_easy_setopt(curl, CURLOPT_HTTPPOST, post);
            curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, callback);
            result_code = curl_easy_perform(curl);
            if (result_code != CURLE_OK) {
                fprintf(stderr, "curl_easy_perform() failed: %s\n",
                        curl_easy_strerror(result_code));
                is_success = 1;
                return is_success;
            }
            json_result = licensePlate_result;
            curl_easy_cleanup(curl);
            is_success = 0;
        } else {
            fprintf(stderr, "curl_easy_init() failed.");
            is_success = 1;
        }
        return is_success;
    }
    <?php
    /**
    * 发起http post请求(REST API), 并获取REST请求的结果
    * @param string $url
    * @param string $param
    * @return - http response body if succeeds, else false.
    */
    function request_post($url = '', $param = '')
    {
        if (empty($url) || empty($param)) {
            return false;
        }
    
        $postUrl = $url;
        $curlPost = $param;
        // 初始化curl
        $curl = curl_init();
        curl_setopt($curl, CURLOPT_URL, $postUrl);
        curl_setopt($curl, CURLOPT_HEADER, 0);
        // 要求结果为字符串且输出到屏幕上
        curl_setopt($curl, CURLOPT_RETURNTRANSFER, 1);
        curl_setopt($curl, CURLOPT_SSL_VERIFYPEER, false);
        // post提交方式
        curl_setopt($curl, CURLOPT_POST, 1);
        curl_setopt($curl, CURLOPT_POSTFIELDS, $curlPost);
        // 运行curl
        $data = curl_exec($curl);
        curl_close($curl);
    
        return $data;
    }
    
    $token = '[调用鉴权接口获取的token]';
    $url = 'https://aip.baidubce.com/rest/2.0/ocr/v1/license_plate?access_token=' . $token;
    $img = file_get_contents('[本地文件路径]');
    $img = base64_encode($img);
    $bodys = array(
        'image' => $img
    );
    $res = request_post($url, $bodys);
    
    var_dump($res);
    using System;
    using System.IO;
    using System.Net;
    using System.Text;
    using System.Web;
    
    namespace com.baidu.ai
    {
        public class LicensePlate
        {
            // 车牌识别
            public static string licensePlate()
            {
                string token = "[调用鉴权接口获取的token]";
                string host = "https://aip.baidubce.com/rest/2.0/ocr/v1/license_plate?access_token=" + token;
                Encoding encoding = Encoding.Default;
                HttpWebRequest request = (HttpWebRequest)WebRequest.Create(host);
                request.Method = "post";
                request.KeepAlive = true;
                // 图片的base64编码
                string base64 = getFileBase64("[本地图片文件]");
                String str = "image=" + HttpUtility.UrlEncode(base64);
                byte[] buffer = encoding.GetBytes(str);
                request.ContentLength = buffer.Length;
                request.GetRequestStream().Write(buffer, 0, buffer.Length);
                HttpWebResponse response = (HttpWebResponse)request.GetResponse();
                StreamReader reader = new StreamReader(response.GetResponseStream(), Encoding.Default);
                string result = reader.ReadToEnd();
                Console.WriteLine("车牌识别:");
                Console.WriteLine(result);
                return result;
            }
    
            public static String getFileBase64(String fileName) {
                FileStream filestream = new FileStream(fileName, FileMode.Open);
                byte[] arr = new byte[filestream.Length];
                filestream.Read(arr, 0, (int)filestream.Length);
                string baser64 = Convert.ToBase64String(arr);
                filestream.Close();
                return baser64;
            }
        }
    }

    返回说明

    返回参数

    参数 类型 是否必须 说明
    log_id uint64 请求标识码,随机数,唯一。
    color string 车牌颜色:支持blue、green、yellow
    number string 车牌号码
    probability string 车牌中每个字符的置信度,区间为0-1
    vertexes_location int 返回文字外接多边形顶点位置

    返回示例

    {
    	"errno": 0,
    	"msg": "success",
    	"data": {
    		"log_id": "5327722537189137631",
    		"words_result": {
    			"color": "green",
    			"number": "苏AD12267",
    			"probability": [
    				1,
    				0.9999977350235,
    				0.99999630451202,
    				0.99999868869781,
    				0.99998331069946,
    				0.99999988079071,
    				0.9531751871109,
    				0.99922955036163
    			],
    			"vertexes_location": [
    				{
    					"y": 223,
    					"x": 170
    				},
    				{
    					"y": 223,
    					"x": 282
    				},
    				{
    					"y": 256,
    					"x": 282
    				},
    				{
    					"y": 256,
    					"x": 170
    				}
    			]
    		}
    	}
    }
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