/green/image/asyncscan - Content Moderation - Alibaba Cloud Documentation Center

Submits asynchronous optical character recognition (OCR) tasks and queries asynchronous OCR results. You can call this operation to submit the OCR tasks to detect and obtain text in images.

Description of the /green/image/asyncscan operation

Operation: /green/image/asyncscan

You can call this operation to submit asynchronous image moderation tasks. For more information about how to construct an HTTP request, see Request syntax. You can also select an existing HTTP request. For more information, see SDK overview.

Billing method:
You are charged for calling this operation. For more information about the billing methods, see Content Moderation Pricing.
Response timeout:
The maximum response time that is allowed for a synchronous moderation request is 6 seconds. If the moderation is not completed within 6 seconds, a timeout error is returned. If you do not need to obtain moderation results in real time, you can send asynchronous moderation requests. In most cases, we recommend that you send synchronous moderation requests because synchronous moderation operations are easier to call. We recommend that you set the timeout period to 6 seconds for calling synchronous moderation operations.
Returned results:
If you send asynchronous moderation requests, the moderation results are not returned in real time. To obtain moderation results, you can poll the moderation results at regular intervals or enable callback notification. The moderation results are retained for up to 1 hour.
- Enable callback notification to obtain moderation results: When you submit asynchronous moderation tasks, you can specify a callback URL to receive moderation results in the callback parameter of the moderation request. For more information about the callback parameter, see Request parameters.
- Poll moderation results at regular intervals: You do not need to set the callback parameter when you submit asynchronous moderation tasks. After you submit the tasks, you can call the /green/video/results operation to query moderation results. For more information about the operation, see Description of the /green/image/results operation.
Limits on images:
- The URLs of images must be HTTP or HTTPS URLs.
- The images must be in the PNG, JPG, JPEG, BMP, GIF, or WEBP format.
- An image can be up to 20 MB in size. The limit for the image size is applicable to both synchronous and asynchronous moderation operations.
- The duration for downloading an image is limited to 3 seconds. If an image fails to be downloaded within 3 seconds, a timeout error is returned.
- We recommend that you submit images of at least 256 × 256 pixels to ensure the moderation effects.
- The response time of an operation for moderating images varies based on the duration for downloading these images. Make sure that you use a stable and reliable storage service to store the images to be moderated. We recommend that you use Object Storage Service (OSS) or Content Delivery Network (CDN).

QPS limit

You can call this operation up to 10 times per second per account. If the number of calls per second exceeds the limit, throttling is triggered. As a result, your business may be affected. We recommend that you take note of the limit when you call this operation.

Request parameters


Parameter	Type	Required	Example	Description
bizType	String	No	default	The business scenario. You can create a business scenario in the Content Moderation console. For more information, see Customize policies for machine-assisted moderation.
scenes	StringArray	Yes	["ocr"]	The moderation scenario. Set the value to ocr.
callback	String	No	http://www.aliyundoc.com/xx.json	The callback URL for notifying you of asynchronous moderation results. HTTP and HTTPS URLs are supported. If you do not set this parameter, you must poll moderation results at regular intervals. If you set the callback parameter in the moderation request, make sure that the specified HTTP or HTTPS URL meets the following requirements: supports the POST method, uses UTF-8 to encode the transmitted data, and supports the checksum and content parameters. To send moderation results to the specified callback URL, Content Moderation returns the checksum and content parameters in callback notifications based on the following rules and format: checksum: a string in the `UID + Seed + Content` format that is generated by the Secure Hash Algorithm 256 (SHA-256) algorithm. UID indicates the ID of your Alibaba Cloud account. You can query the ID in the Alibaba Cloud Management Console. To prevent data tampering, you can use the SHA-256 algorithm to generate a string when your server receives a callback notification and verify the string against the received checksum parameter. Note UID must be the ID of an Alibaba Cloud account, but not the ID of a RAM user. content: the JSON-formatted string to be parsed to the callback data in the JSON format. For more information about the format of the content parameter, see the sample success responses of each operation that you can call to query asynchronous moderation results. Note If your server receives a callback notification, the server sends HTTP status code 200 to Content Moderation. If your server fails to receive a callback notification, the server sends other HTTP status codes to Content Moderation. If your server fails to receive a callback notification, Content Moderation continues to push the callback notification until your server receives it. Content Moderation can push a callback notification repeatedly for up to 16 times. After 16 times, Content Moderation stops pushing the callback notification. In this case, we recommend that you check the status of the callback URL.
seed	String	No	aabbcc123	A random string that is used to generate a signature for the callback notification request. The string can be up to 64 characters in length and can contain letters, digits, and underscores (_). You can customize this string. It is used to verify the callback notification request when Content Moderation pushes callback notifications to your server. Note This parameter is required if you set the callback parameter.
cryptType	String	No	SHA256	The encryption algorithm used to encrypt the callback notification content when you enable callback notification. Content Moderation encrypts the returned string by using the encryption algorithm that you specify and sends the encrypted string to the callback URL. The returned string is in the `UID + Seed + Content` format. Valid values: SHA256: The HMAC-SHA256 encryption algorithm is used. This is the default value. SM3: The HMAC-SM3 encryption algorithm is used, and a hexadecimal string is returned. The string consists of lowercase letters and digits. For example, 66c7f0f462eeedd9d1f2d46bdc10e4e24167c4875cf2f7a2297da02b8f4ba8e0 is returned after you encrypt abc by using the HMAC-SM3 encryption algorithm.
tasks	JSONArray	Yes		The list of objects that you want to moderate. The JSON array can contain one or more elements. Each element is a structure. The JSON array can contain up to 100 elements. In other words, you can submit up to 100 moderation objects at a time. To submit 100 moderation objects at a time, you must raise the relevant concurrency limit to a number greater than 100. For more information about the structure of each element, see task.

Table 1. task
Parameter	Type	Required	Example	Description
dataId	String	No	test_data_xxxx	The data ID. Make sure that each ID is unique in a request.
url	String	Yes	https://www.aliyundoc.com/test_image_xxxx.png	The HTTP or HTTPS URL that can be accessed over the Internet. The URL is up to 2,048 characters in length.
interval	Integer	No	2	The interval between two frames that are consecutively captured. This parameter is dedicated for GIF or long image moderation. A GIF image can be regarded as an array of frames. One frame is captured for moderation from every n frames, where n is specified by the interval parameter. The system captures frames from GIF images only when this parameter is specified. Long images can be in portrait or horizontal mode. To moderate a long portrait image, you can calculate the total number of frames in the following way: divide the height by the width and round the result to the nearest integer. In a long portrait image, the height is greater than 400 pixels, and the ratio of height to width is greater than 2.5. To moderate a long horizontal image, you can calculate the total number of frames in the following way: divide the width by the height and round the result to the nearest integer. In a long horizontal image, the width is greater than 400 pixels, and the ratio of width to height is greater than 2.5. By default, only the first frame of a GIF image or a long image is moderated. You can use the interval parameter to specify the interval between two frames that the system consecutively captures. This helps reduce moderation costs. Note The interval and maxFrames parameters must be used in pairs. For example, the interval parameter is set to 2 and the maxFrames parameter is set to 100 for moderating a GIF image or a long image. In this example, one out of every two frames is moderated and a maximum of 100 frames are moderated. The fee is calculated based on the actual number of moderated frames.
maxFrames	Integer	No	100	The maximum number of frames to be captured. This parameter is dedicated for GIF or long image moderation. Default value: 1. If the value of the `interval` parameter multiplied by that of the `maxFrames` parameter is smaller than the total number of frames in a GIF image or a long image, the interval for capturing frames is automatically changed to the integer rounded from the result of dividing the total number of frames in the image by the value of the maxFrames parameter. This helps improve the overall moderation effects.

Response parameters


Parameter	Type	Example	Description
code	Integer	200	The returned HTTP status code. For more information, see Common error codes.
msg	String	OK	The message that is returned for the request.
dataId	String	test_data_xxxx	The ID of the moderated object. Note If you set the dataId parameter in the moderation request, the value of the dataId request parameter is returned here.
taskId	String	aaa25f95-4892-4d6b-aca9-7939bc6e9baa-148619876****	The ID of the moderation task.
url	String	https://www.aliyundoc.com/test_image_xxxx.png	The HTTP or HTTPS URL that can be accessed over the Internet. The URL is up to 2,048 characters in length.
extras	JSONObject	xxx	If you set the extras parameter in the moderation request, the value of the extras request parameter is returned here. Note This parameter may be subject to changes. Use the latest value of this parameter.

Examples

Sample requests

http(s)://[Endpoint]/green/image/asyncscan
&<Common request parameters>
{
    "scenes": [
        "ocr"
    ],
    "tasks": [
        {
            "dataId": "test_data_xxxx",
            "url": "https://www.aliyundoc.com/test_image_xxxx.png"
        }
    ]
}

Sample success responses

{
    "code": 200,
    "msg": "OK",
    "requestId": "92AD868A-F5D2-4AEA-96D4-E1273B8E074C",
    "data": [
        {
            "code": 200,
            "msg": "OK",
            "dataId": "test_data_xxxx",
            "taskId": "aaa25f95-4892-4d6b-aca9-7939bc6e9baa-148619876****",
            "url": "https://www.aliyundoc.com/test_image_xxxx.png"
        }
    ]
}

Description of the /green/image/results operation

Operation: /green/image/results

You can call this operation to query asynchronous OCR results. For more information about how to construct an HTTP request, see Request syntax. You can also select an existing HTTP request. For more information, see SDK overview.

Billing method:
This operation is free of charge.
Response timeout:
We recommend that you query moderation results at least 30 seconds after you send an asynchronous moderation request. Content Moderation retains moderation results for up to 4 hours. If you query moderation results after 4 hours, the results are deleted.