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

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

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.
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    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.
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    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.
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    # 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.
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    # 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.
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    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.
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    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.

Status Codes

Status Code

Description

200

Example response for a successful request

400

Example response for a failed request

See Status Codes.

Error Codes

See Error Codes.