This topic describes how to call an operation to submit synchronous optical character recognition (OCR) tasks and obtain OCR results in a synchronous way. It intends to help you construct an HTTP call request.

  • For more information about how to construct an HTTP request, see Request structure.
  • You can also select an existing HTTP request. For more information, see SDK overview.

Description

Operation: /green/image/scan

Note You are charged for calling this operation. For more information about the billing method, see Content Moderation pricing.

Notes for synchronous and asynchronous moderation

The maximum response time allowed for a synchronous moderation request is 6s. If the moderation is not completed within 6s, a timeout error is returned. If you do not have a high demand on getting the results in real time, you can send asynchronous moderation requests. In other cases, we recommend that you send synchronous moderation requests because it is easier to call the operations for synchronous moderation. We recommend that you set the timeout period to 6s for calling the operations for synchronous moderation.

Generally, OCR results are returned within 1s after you send a synchronous OCR request. The time may be increased in some special scenarios where a large number of requests are to be processed in the system, the size of images is large, or the images contain a large number of words. The speed of OCR is inversely proportional to the number of words in images. If the images contain a large number of words, we recommend that you call the operation of submitting asynchronous OCR tasks. For more information, see Detect text in images asynchronously.

Limits on images
  • The images must use HTTP or HTTPS URLs.
  • The images must be in the following formats: PNG, JPG, JPEG, BMP, GIF, or WEBP.
  • The size of an image can be up to 10 MB. This rule is applicable to both synchronous and asynchronous calls. If you have any special requirements, for example, moderating images greater than 10 MB in size, you can submit a ticket to raise the threshold.
  • The duration for downloading an image is limited to 3s. If an image fails to be downloaded within 3s, a timeout error is returned.
  • We recommend that you submit images of at least 256 × 256 pixels to guarantee the moderation effects.
  • The response time of an operation for moderating images depends on the download duration of images. Make sure that you use a stable and reliable storage service to store the images to be moderated. We recommend that you use Alibaba Cloud Object Storage Service (OSS) or Content Delivery Network (CDN).

Request parameters

Parameter Type Required Description
bizType String No The business scenario. You can customize content moderation policies to apply different moderation standards or algorithm policies to different business scenarios. You can create a business scenario by specifying bizType in the Alibaba Cloud Content Moderation console. Alternatively, you can submit a ticket to ask Alibaba Cloud engineers to help you create a business scenario.
scenes String array Yes The moderation scenario. Set the value to ocr.
tasks JSON array Yes The list of OCR tasks. Each element in the JSON array is an OCR task structure, that is, each element corresponds to an image. The JSON array can contain a maximum of 10 elements, that is, you can detect text in a maximum of 10 images at a time. For more information about the structure of each element, see task.
Table 1. task
Parameter Type Required Description
dataId String No The ID of the image to be moderated. Make sure that each ID is unique in a request.
url String Yes The URL of the image to be moderated.
interval Integer No The interval between two frames that are consecutively captured. This parameter is dedicated for GIF or long image moderation. A GIF image can be treated 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 either portrait or horizontal mode.
  • For a long portrait image, of which the height is greater than 400 pixels and the ratio of height to width is greater than 2.5, you can divide the height by the width and round up the result to the nearest integer as the total number of frames.
  • For a long horizontal image, of which the width is greater than 400 pixels and the ratio of width to height is greater than 2.5, you can divide the width by the height and round up the result to the nearest integer as the total number of frames.
Note By default, only the first frame of a GIF or long image is moderated. Instead of having all the frames moderated, you can set the interval parameter to specify the interval between two frames that the system consecutively captures. This can help reduce costs. This parameter must be used together with the maxFrames parameter. Assume that the interval parameter is set to 2 and the maxFrames parameter is set to 100 for moderating a GIF or long image. In this case, one out of every two frames is moderated and a maximum of 100 frames can be moderated. The fee is calculated based on the actual number of moderated frames.
maxFrames Integer No The maximum number of frames to be captured. This parameter is dedicated for GIF or long image moderation. Default value: 1.

If the product of interval and maxFrames is smaller than the total number of frames in a GIF or long image, the interval for capturing frames is automatically changed to the integer rounded up from the result of dividing the total number of frames in the image by maxFrames. This helps improve the overall moderation effect.

Response parameters

Parameter Type Required Description
code Integer Yes The HTTP status code returned for the OCR task.
msg String Yes The message returned for the OCR task.
dataId String No The ID of the moderated image, which you specify in the dataId parameter of the OCR request.
taskId String Yes The ID of the OCR task.
url String Yes The URL of the moderated image, which you specify in the url parameter of the OCR request.
results Array No The return results of the OCR task. If HTTP status code 200 is returned, indicating a successful call, the array in the return results may contain one or more elements. Each element is a structure. For more information about the structure of each element, see result.
Table 2. result
Parameter Type Required Description
scene String Yes The moderation scenario. Set the value to ocr.
label String Yes The category of the OCR results. Valid values:
  • normal: The image is normal and does not contain text.
  • ocr: The image contains text.
suggestion String Yes The machine-assisted moderation result of the moderated image. Valid values:
  • pass: The image is normal and does not require further actions.
  • review: The image requires human review.
rate Floating point Yes The probability that the moderated image falls into the detected category. You can ignore this parameter in the OCR scenario.
ocrLocations Array No The information about the single piece of text in the moderated static image, including the text, text size, and text location. For more information about the structure, see ocrLocation.
ocrData Array No The combination of all text in the moderated static image. Generally, the text combination is stored in the first element of the array.
frames Array No The frames captured from the moderated GIF image and text detected in each frame.
Table 3. ocrLocation
Parameter Type Required Description
text String Yes The single piece of text detected in the moderated image.
x Floating point Yes The distance between the upper-left corner of the text area and the y-axis, with the upper-left corner of the image being the coordinate origin.
y Floating point Yes The distance between the upper-left corner of the text area and the x-axis, with the upper-left corner of the image being the coordinate origin.
w Floating point Yes The width of the text area.
h Floating point Yes The height of the text area.

Examples

Sample requests
{
  "scenes": ["ocr"],
  "tasks": [
    {
      "dataId": "f0683af0-e4ce-4e82-9e0e-a3027a6c3cc1",
      "url": "https://img.alicdn.com/tfs/TB1xxxXXaHAVXa-225-225.png"
    } 
  ]
}
Sample responses
{
  "code": 200,
  "data": [
    {
      "code": 200,
      "dataId": "f0683af0-e4ce-4e82-9e0e-a3027a6c3cc1",
      "extras": {},
      "msg": "OK",
      "results": [
        {
          "label": "ocr",
          "ocrData": [
            "hello, this is a test text."
          ],
          "ocrLocations": [
            {
              "h": 26,
              "text": "hello",
              "w": 83,
              "x": 41,
              "y": 84
            },
            {
              "h": 25,
              "text": " this is a test text.",
              "w": 95,
              "x": 78,
              "y": 114
            }
          ],
          "rate": 99.91,
          "scene": "ocr",
          "suggestion": "review"
        }
      ],
      "taskId": "img6OMJ8obXH8m7iH$PRl8Yd2-1scxnD",
      "url": "https://img.alicdn.com/tfs/TB1xxxXXaHAVXa-225-225.jpg"
    }
  ],
  "msg": "OK",
  "requestId": "C4AB08A9-AD75-4410-859B-0B9EF6DFC3C4"
}