Help Center/ Optical Character Recognition/ API Reference/ API/ Thailand Plate Number

Updated on 2024-06-19 GMT+08:00

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Thailand Plate Number

Function

This API detects and extracts license plate information from images of Thailand license plates and returns the license plate number and location. For details about the constraints on using this API, see Constraints and Limitations. For details about how to use this API, see Introduction to OCR.

Figure 1 Example Thailand plate number
Click to enlarge

Constraints and Limitations

Only images in PNG, JPG, JPEG, BMP, or TIFF format can be recognized.
No side of the image can be smaller than 15 or larger than 8,192 pixels.
A license plate can be rotated to any angle.
Illuminated or dark images can be recognized, but the accuracy may be compromised.

Calling Method

For details, see Calling APIs.

Prerequisites

Before using this API, subscribe to the service and complete authentication. For details, see Subscribing to an OCR Service and Authentication.

Before you use the service for the first time, subscribe to the service by clicking Subscribe. You only need to subscribe to the service once. If you have not subscribed to the service yet, error "ModelArts.4204" will be displayed when you call this API. Before you call the API, log in to the OCR console and subscribe to the corresponding service. Ensure that you make the subscription to the service in the same region where you want to call this API.

URI

POST /v2/{project_id}/ocr/thailand-license-plate

**Table 1** URI parameters
Parameter	Mandatory	Description
endpoint	Yes	Endpoint, which is the request address for calling an API. The endpoint varies depending on services in different regions. For more details, see Endpoints.
project_id	Yes	Project ID, which can be obtained by referring to Obtaining a Project ID.

Request Parameters

**Table 2** Request header parameters
Parameter	Mandatory	Type	Description
X-Auth-Token	Yes	String	User token Used to obtain the permission to call APIs. The token is the value of X-Subject-Token in the response header in Authentication.
Content-Type	Yes	String	MIME type of the request body. The value is application/json.
Enterprise-Project-Id	No	String	Enterprise project ID. OCR uses Enterprise Project Management Service (EPS) to split fees for resources used by different user groups and users. To obtain the enterprise project ID, go to the Enterprise Project Management console, click the enterprise project name, and obtain the enterprise project ID on the enterprise project details page. For details about how to create an enterprise project, see Optical Character Recognition User Guide. NOTE: After an enterprise project is created, parameter transfer involves the following scenarios: If a correct enterprise project ID is carried and the OCR service can be used properly, the bills will be categorized under the corresponding enterprise project for that ID. If an enterprise project ID that is in the correct format but does not actually exist is carried, and the OCR service can be used properly, the bills will display the corresponding non-existent enterprise project ID. If no enterprise project ID or an enterprise project ID with incorrect format (such as special characters) is carried, and the OCR service can be used properly, the bills will be categorized under default.

**Table 3** Request body parameters
Parameter	Mandatory	Type	Description
image	No	String	Set either this parameter or url. Base64 encoded string of an image file. The image file has a size limit of 10 MB. No side of the image can be smaller than 15 or larger than 8,192 pixels. Only images in JPG, PNG, BMP, TIFF, or JPEG format can be recognized. An example is /9j/4AAQSkZJRgABAg.... If the image data contains an unnecessary prefix, the error "The image format is not supported" is reported.
url	No	String	Set either this parameter or image. Image URL. Currently, the following URLs are supported: Public HTTP/HTTPS URL URL provided by OBS. You need to be authorized to use OBS data, including service authorization, temporary authorization, and anonymous public authorization. For details, see Configuring Access Permissions of OBS. NOTE: The API response time depends on the image download time. If the image download takes a long time, the API call will fail. Ensure that the storage service where the image to be detected resides is stable and reliable. OBS is recommended for storing image data.

Response Parameters

Status code: 200

**Table 4** Response body parameter
Parameter	Type	Description
result	Array of ThailandLicensePlateItem objects	Calling result This parameter is not returned when the API fails to be called.

**Table 5** ThailandLicensePlateItem
Parameter	Type	Description
plate_number	String	License plate content
plate_location	Array<Array<Integer>>	List of location information about a license plate, including the 2D coordinates (x, y) of four vertexes in the text area, where the coordinate origin is the upper-left corner of the image, theX axis is horizontal, and the Y axis is vertical.
confidence	Float	Confidence of a field. The value ranges from 0 to 1. A higher confidence indicates a higher accuracy of the field identified. The confidence is calculated using algorithms and is not equal to the accuracy.
province	String	Province where the license plate is registered

Status code: 400

**Table 6** Response body parameters
Parameter	Type	Description
error_code	String	Error code of a failed API call. For details, see Error Codes. This parameter is not returned for a successful call.
error_msg	String	Error message when the API call fails This parameter is not returned when the API is successfully called.

Example Request

endpoint is the request URL for calling an API. Endpoints vary depending on services and regions. For details, see Endpoints.
For example, Thailand Plate Number OCR is deployed in the AP-Bangkok region. The endpoint is ocr.ap-southeast-2.myhuaweicloud.com or ocr.ap-southeast-2.myhuaweicloud.cn. The request URL is https://ocr.ap-southeast-2.myhuaweicloud.com/v2/{project_id}/ocr/thailand-license-plate. project_id is the project ID. For how to obtain the project ID, see Obtaining a Project ID.
For details about how to obtain a token, see Making an API Request.

Request example (Method 1: Use the image Base64 string.)

POST https://{endpoint}/v2/{project_id}/ocr/thailand-license-plate

Request Header:
Content-Type: application/json
X-Auth-Token: MIINRwYJKoZIhvcNAQcCoIINODCCDTQCAQExDTALBglghkgBZQMEAgEwgguVBgkqhkiG...
Request Body: 
{
   "image":"/9j/4AAQSkZJRgABAgEASABIAAD/4RFZRXhpZgAATU0AKgAAAA..."
}

Request example (Method 2: Use the image URL.)

POST https://{endpoint}/v2/{project_id}/ocr/thailand-license-plate

Request Header:
Content-Type: application/json
X-Auth-Token: MIINRwYJKoZIhvcNAQcCoIINODCCDTQCAQExDTALBglghkgBZQMEAgEwgguVBgkqhkiG...
Request Body: 
{
   "url":"https://BucketName.obs.xxxx.com/ObjectName"
}

Sample code for a Python 3 request (For codes in other languages, refer to the following sample or use OCR SDK.)

# encoding:utf-8

import requests
import base64

url = "https://{endpoint}/v2/{project_id}/ocr/thailand-license-plate"
token = "Actual token value obtained by the user"
headers = {'Content-Type': 'application/json', 'X-Auth-Token': token}

imagepath = r'./data/thailand-license-plate-demo.png' # Read a local image.
with open(imagepath, "rb") as bin_data:
    image_data = bin_data.read()
image_base64 = base64.b64encode(image_data).decode("utf-8")  # Use the Base64 encoded string of the image.
payload = {"image": image_base64}
response = requests.post(url, headers=headers, json=payload)
print(response.text)

Example Response

Status code: 200

Example response for a successful request

{
  "result" : [ {
    "plate_number" : "กง XXX4",
    "province" : "มหาสารคาม",
    "confidence" : 0.9225,
    "plate_location" : [ [ 370, 881 ], [ 2591, 881 ], [ 2591, 2281 ], [ 370, 2281 ] ]
  } ]
}

Status code: 400

Example response for a failed request

{
    "error_code": "AIS.0103", 
    "error_msg": "The image size does not meet the requirements." 
}

Example SDK Code

The example SDK code is as follows:

You are advised to update the SDKs to the latest versions before use to prevent the local outdated SDKs from being unable to use the latest OCR functions.

Transfer the Base64 encoded string of the Thailand plate number image for recognition.

        
         
           
           
             package com.huaweicloud.sdk.test;

import com.huaweicloud.sdk.core.auth.ICredential;
import com.huaweicloud.sdk.core.auth.BasicCredentials;
import com.huaweicloud.sdk.core.exception.ConnectionException;
import com.huaweicloud.sdk.core.exception.RequestTimeoutException;
import com.huaweicloud.sdk.core.exception.ServiceResponseException;
import com.huaweicloud.sdk.ocr.v1.region.OcrRegion;
import com.huaweicloud.sdk.ocr.v1.*;
import com.huaweicloud.sdk.ocr.v1.model.*;


public class RecognizeThailandLicensePlateSolution {

    public static void main(String[] args) {
        // The AK and SK used for authentication are hard-coded or stored in plaintext, which has great security risks. It is recommended that the AK and SK be stored in ciphertext in configuration files or environment variables and decrypted during use to ensure security.
        // In this example, AK and SK are stored in environment variables for authentication. Before running this example, set environment variables CLOUD_SDK_AK and CLOUD_SDK_SK in the local environment
        String ak = System.getenv("CLOUD_SDK_AK");
        String sk = System.getenv("CLOUD_SDK_SK");

        ICredential auth = new BasicCredentials()
                .withAk(ak)
                .withSk(sk);

        OcrClient client = OcrClient.newBuilder()
                .withCredential(auth)
                .withRegion(OcrRegion.valueOf("<YOUR REGION>"))
                .build();
        RecognizeThailandLicensePlateRequest request = new RecognizeThailandLicensePlateRequest();
        ThailandLicensePlateRequestBody body = new ThailandLicensePlateRequestBody();
        body.withImage("/9j/4AAQSkZJRgABAgEASABIAAD/4RFZRXhpZgAATU0AKgAAAA...");
        request.withBody(body);
        try {
            RecognizeThailandLicensePlateResponse response = client.recognizeThailandLicensePlate(request);
            System.out.println(response.toString());
        } catch (ConnectionException e) {
            e.printStackTrace();
        } catch (RequestTimeoutException e) {
            e.printStackTrace();
        } catch (ServiceResponseException e) {
            e.printStackTrace();
            System.out.println(e.getHttpStatusCode());
            System.out.println(e.getRequestId());
            System.out.println(e.getErrorCode());
            System.out.println(e.getErrorMsg());
        }
    }
}

            

          

        
       

Transfer the URL of the Thailand plate number image for recognition.

        
         
           
           
             package com.huaweicloud.sdk.test;

import com.huaweicloud.sdk.core.auth.ICredential;
import com.huaweicloud.sdk.core.auth.BasicCredentials;
import com.huaweicloud.sdk.core.exception.ConnectionException;
import com.huaweicloud.sdk.core.exception.RequestTimeoutException;
import com.huaweicloud.sdk.core.exception.ServiceResponseException;
import com.huaweicloud.sdk.ocr.v1.region.OcrRegion;
import com.huaweicloud.sdk.ocr.v1.*;
import com.huaweicloud.sdk.ocr.v1.model.*;


public class RecognizeThailandLicensePlateSolution {

    public static void main(String[] args) {
        // The AK and SK used for authentication are hard-coded or stored in plaintext, which has great security risks. It is recommended that the AK and SK be stored in ciphertext in configuration files or environment variables and decrypted during use to ensure security.
        // In this example, AK and SK are stored in environment variables for authentication. Before running this example, set environment variables CLOUD_SDK_AK and CLOUD_SDK_SK in the local environment
        String ak = System.getenv("CLOUD_SDK_AK");
        String sk = System.getenv("CLOUD_SDK_SK");

        ICredential auth = new BasicCredentials()
                .withAk(ak)
                .withSk(sk);

        OcrClient client = OcrClient.newBuilder()
                .withCredential(auth)
                .withRegion(OcrRegion.valueOf("<YOUR REGION>"))
                .build();
        RecognizeThailandLicensePlateRequest request = new RecognizeThailandLicensePlateRequest();
        ThailandLicensePlateRequestBody body = new ThailandLicensePlateRequestBody();
        body.withUrl("https://BucketName.obs.myhuaweicloud.com/ObjectName");
        request.withBody(body);
        try {
            RecognizeThailandLicensePlateResponse response = client.recognizeThailandLicensePlate(request);
            System.out.println(response.toString());
        } catch (ConnectionException e) {
            e.printStackTrace();
        } catch (RequestTimeoutException e) {
            e.printStackTrace();
        } catch (ServiceResponseException e) {
            e.printStackTrace();
            System.out.println(e.getHttpStatusCode());
            System.out.println(e.getRequestId());
            System.out.println(e.getErrorCode());
            System.out.println(e.getErrorMsg());
        }
    }
}

            

          

        
       

Transfer the Base64 encoded string of the Thailand plate number image for recognition.

        
         
           
           
             # coding: utf-8

from huaweicloudsdkcore.auth.credentials import BasicCredentials
from huaweicloudsdkocr.v1.region.ocr_region import OcrRegion
from huaweicloudsdkcore.exceptions import exceptions
from huaweicloudsdkocr.v1 import *

if __name__ == "__main__":
    # The AK and SK used for authentication are hard-coded or stored in plaintext, which has great security risks. It is recommended that the AK and SK be stored in ciphertext in configuration files or environment variables and decrypted during use to ensure security.
    # In this example, AK and SK are stored in environment variables for authentication. Before running this example, set environment variables CLOUD_SDK_AK and CLOUD_SDK_SK in the local environment
    ak = os.getenv("CLOUD_SDK_AK")
    sk = os.getenv("CLOUD_SDK_SK")

    credentials = BasicCredentials(ak, sk) \

    client = OcrClient.new_builder() \
        .with_credentials(credentials) \
        .with_region(OcrRegion.value_of("<YOUR REGION>")) \
        .build()

    try:
        request = RecognizeThailandLicensePlateRequest()
        request.body = ThailandLicensePlateRequestBody(
            image="/9j/4AAQSkZJRgABAgEASABIAAD/4RFZRXhpZgAATU0AKgAAAA..."
        )
        response = client.recognize_thailand_license_plate(request)
        print(response)
    except exceptions.ClientRequestException as e:
        print(e.status_code)
        print(e.request_id)
        print(e.error_code)
        print(e.error_msg)

            

          

        
       

Transfer the URL of the Thailand plate number image for recognition.

        
         
           
           
             # coding: utf-8

from huaweicloudsdkcore.auth.credentials import BasicCredentials
from huaweicloudsdkocr.v1.region.ocr_region import OcrRegion
from huaweicloudsdkcore.exceptions import exceptions
from huaweicloudsdkocr.v1 import *

if __name__ == "__main__":
    # The AK and SK used for authentication are hard-coded or stored in plaintext, which has great security risks. It is recommended that the AK and SK be stored in ciphertext in configuration files or environment variables and decrypted during use to ensure security.
    # In this example, AK and SK are stored in environment variables for authentication. Before running this example, set environment variables CLOUD_SDK_AK and CLOUD_SDK_SK in the local environment
    ak = os.getenv("CLOUD_SDK_AK")
    sk = os.getenv("CLOUD_SDK_SK")

    credentials = BasicCredentials(ak, sk) \

    client = OcrClient.new_builder() \
        .with_credentials(credentials) \
        .with_region(OcrRegion.value_of("<YOUR REGION>")) \
        .build()

    try:
        request = RecognizeThailandLicensePlateRequest()
        request.body = ThailandLicensePlateRequestBody(
            url="https://BucketName.obs.myhuaweicloud.com/ObjectName"
        )
        response = client.recognize_thailand_license_plate(request)
        print(response)
    except exceptions.ClientRequestException as e:
        print(e.status_code)
        print(e.request_id)
        print(e.error_code)
        print(e.error_msg)

            

          

        
       

Transfer the Base64 encoded string of the Thailand plate number image for recognition.

        
         
           
           
             package main

import (
	"fmt"
	"github.com/huaweicloud/huaweicloud-sdk-go-v3/core/auth/basic"
    ocr "github.com/huaweicloud/huaweicloud-sdk-go-v3/services/ocr/v1"
	"github.com/huaweicloud/huaweicloud-sdk-go-v3/services/ocr/v1/model"
    region "github.com/huaweicloud/huaweicloud-sdk-go-v3/services/ocr/v1/region"
)

func main() {
    // The AK and SK used for authentication are hard-coded or stored in plaintext, which has great security risks. It is recommended that the AK and SK be stored in ciphertext in configuration files or environment variables and decrypted during use to ensure security.
    // In this example, AK and SK are stored in environment variables for authentication. Before running this example, set environment variables CLOUD_SDK_AK and CLOUD_SDK_SK in the local environment
    ak := os.Getenv("CLOUD_SDK_AK")
    sk := os.Getenv("CLOUD_SDK_SK")

    auth := basic.NewCredentialsBuilder().
        WithAk(ak).
        WithSk(sk).
        Build()

    client := ocr.NewOcrClient(
        ocr.OcrClientBuilder().
            WithRegion(region.ValueOf("<YOUR REGION>")).
            WithCredential(auth).
            Build())

    request := &model.RecognizeThailandLicensePlateRequest{}
	imageThailandLicensePlateRequestBody:= "/9j/4AAQSkZJRgABAgEASABIAAD/4RFZRXhpZgAATU0AKgAAAA..."
	request.Body = &model.ThailandLicensePlateRequestBody{
		Image: &imageThailandLicensePlateRequestBody,
	}
	response, err := client.RecognizeThailandLicensePlate(request)
	if err == nil {
        fmt.Printf("%+v\n", response)
    } else {
        fmt.Println(err)
    }
}

            

          

        
       

Transfer the URL of the Thailand plate number image for recognition.

        
         
           
           
             package main

import (
	"fmt"
	"github.com/huaweicloud/huaweicloud-sdk-go-v3/core/auth/basic"
    ocr "github.com/huaweicloud/huaweicloud-sdk-go-v3/services/ocr/v1"
	"github.com/huaweicloud/huaweicloud-sdk-go-v3/services/ocr/v1/model"
    region "github.com/huaweicloud/huaweicloud-sdk-go-v3/services/ocr/v1/region"
)

func main() {
    // The AK and SK used for authentication are hard-coded or stored in plaintext, which has great security risks. It is recommended that the AK and SK be stored in ciphertext in configuration files or environment variables and decrypted during use to ensure security.
    // In this example, AK and SK are stored in environment variables for authentication. Before running this example, set environment variables CLOUD_SDK_AK and CLOUD_SDK_SK in the local environment
    ak := os.Getenv("CLOUD_SDK_AK")
    sk := os.Getenv("CLOUD_SDK_SK")

    auth := basic.NewCredentialsBuilder().
        WithAk(ak).
        WithSk(sk).
        Build()

    client := ocr.NewOcrClient(
        ocr.OcrClientBuilder().
            WithRegion(region.ValueOf("<YOUR REGION>")).
            WithCredential(auth).
            Build())

    request := &model.RecognizeThailandLicensePlateRequest{}
	urlThailandLicensePlateRequestBody:= "https://BucketName.obs.myhuaweicloud.com/ObjectName"
	request.Body = &model.ThailandLicensePlateRequestBody{
		Url: &urlThailandLicensePlateRequestBody,
	}
	response, err := client.RecognizeThailandLicensePlate(request)
	if err == nil {
        fmt.Printf("%+v\n", response)
    } else {
        fmt.Println(err)
    }
}

            

          

        
       

For more SDK code examples in various programming languages, see the Sample Code tab on the right of the API Explorer page, which can automatically generate corresponding SDK code examples.