Help Center> Optical Character Recognition> Service Overview> Constraints and Limitations
Updated on 2024-03-22 GMT+08:00
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Constraints and Limitations

Due to various technological and cost issues, there are some constraints on how OCR can be used. System-wide constraints affect all sub-services. Additionally, sub-services are subject to their respective constraints.

ID Document OCR

  • Only images in JPEG, JPG, PNG, BMP, or TIFF format can be recognized.
  • No side of the image can be smaller than 100 or larger than 8,192 pixels.

General Table OCR

  • 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.
  • The area to be recognized must occupy more than 80% of the image. When scanning a table, ensure that the entire table and its surrounding area are included in the image.
  • An image can be rotated to any angle.
  • Text in images with complex backgrounds (such as outdoor scenery or anti-counterfeit watermarks) or distorted table lines cannot be recognized.
  • English and Chinese are supported but support for traditional Chinese characters is limited.

General Text OCR

  • Only images in PNG, JPG, JPEG, BMP, GIF, TIFF, WebP, PCX, ICO, or PSD format can be recognized.
  • No side of the image can be smaller than 15 or larger than 8,192 pixels.
  • The area to be recognized must occupy more than 80% of the image. When scanning a table, ensure that all text and its surrounding area are included in the image.
  • An image can be rotated to any angle.
  • Text in images with complex backgrounds (such as outdoor scenery or anti-counterfeit watermarks) or distorted text cannot be recognized.
  • Supported languages: Chinese, English, some traditional Chinese, Malay, Ukrainian, Hindi, Russian, Vietnamese, Indonesian, Thai, Arabic, German, Latin, French, Italian, Spanish, Portuguese, Romanian, Polish Amharic, Japanese, Korean, Turkish, Norwegian, Danish, Swedish, and Khmer.

Web Image OCR

  • English and Chinese are supported but support for traditional Chinese characters is limited.
  • Only images in JPG, JPEG, PNG, BMP, TIFF, TGA, WEBP, ICO, PCX, or GIF format can be recognized.
  • Common image types are supported, such as mobile phone or desktop screenshots, e-commerce product images, and advertisement design drawings.
  • No side of the image can be smaller than 15 or larger than 8,192 pixels.
  • The characters to be recognized must occupy more than 60% of the image.
  • The web image to be recognized can be rotated to any angle (direction detection must be enabled).

Passport OCR

  • All fields on Chinese mainland passports can be recognized.
  • Passports that are issued by China, Hong Kong (China), Macao (China), Taiwan (China), and other countries and regions and that are with complete machine-readable codes can be recognized.
  • 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.
  • The information page of the passport to be recognized must occupy more than 25% of the image. When scanning a passport, ensure that the entire page is displayed in the image.
  • A passport can be rotated to any angle.
  • The passport in the image can be moderately distorted, but the aspect ratio cannot be distorted by more than 10%.
  • Illuminated or dark images can be recognized, but the accuracy may be compromised.

Thailand ID Card OCR

  • Only ID cards issued by Thailand can be recognized.
  • 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.
  • An ID card to be recognized must occupy more than 25% of the image. When scanning an ID card, ensure that the entire ID card is displayed in the image.
  • An ID card can be rotated to any angle.
  • The ID card in the image can be moderately distorted, but the aspect ratio cannot be distorted by more than 10%.
  • Illuminated or dark images can be recognized, but the accuracy may be compromised.
  • Only the front or back of a single ID card can be identified each time.

Cambodian ID Card OCR

  • Currently, only the front of an ID card can be recognized each time.
  • Only images in PNG, JPG, BMP, or TIFF format can be recognized.
  • No side of the image can be smaller than 15 or larger than 8,192 pixels.
  • An ID card can be rotated to any angle.
  • Illuminated or dark images can be recognized, but the accuracy may be compromised.

Myanmar ID Card OCR

  • Only the national registration cards issued by Myanmar can be recognized.
  • 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 8,000 pixels.
  • An ID card to be recognized must occupy more than 25% of the image. When scanning an ID card, ensure that the entire ID card is displayed in the image.
  • An ID card can be rotated to any angle.
  • The ID card in the image can be moderately distorted, but the aspect ratio cannot be distorted by more than 10%.
  • Illuminated or dark images can be recognized, but the accuracy may be compromised.
  • Only the front or back of a single ID card can be identified each time.

Myanmar Driving License OCR

  • 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 4,096 pixels.
  • Currently, only the front of a driving license can be recognized each time.
  • A driving license can be rotated to any angle.
  • The driving license in the image can be moderately distorted, but the aspect ratio cannot be distorted by more than 10%.
  • Illuminated or dark images can be recognized, but the accuracy may be compromised.

Chile ID Card OCR

  • Only images in PNG, JPG, BMP, or TIFF format can be recognized.
  • No side of the image can be smaller than 15 or larger than 8,192 pixels.
  • Currently, only the front of an ID card can be recognized each time.
  • An ID card can be rotated to any angle.
  • Illuminated or dark images can be recognized, but the accuracy may be compromised.

Vietnam ID Card OCR

  • Only ID cards issued by Vietnam can be recognized.
  • 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.
  • An ID card can be rotated to any angle.
  • Illuminated or dark images, or images with anti-counterfeit watermarks can be recognized, but the accuracy may be compromised.

Peru ID Card OCR

  • Only ID cards issued by Peru can be recognized.
  • 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.
  • An ID card to be recognized must occupy more than 25% of the image. When scanning an ID card, ensure that the entire ID card is displayed in the image.
  • An ID card can be rotated to any angle.
  • The ID card in the image can be moderately distorted, but the aspect ratio cannot be distorted by more than 10%.
  • Illuminated or dark images can be recognized, but the accuracy may be compromised.

Thailand Plate Number OCR

  • 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.

Hong Kong ID Card OCR

  • Only images in PNG, JPG, BMP, or TIFF format can be recognized.
  • No side of the image can be smaller than 15 or larger than 8,192 pixels.
  • An ID card to be recognized must occupy more than 50% of the image. When scanning an ID card, ensure that the entire ID card is displayed in the image.
  • Images can be rotated horizontally to any angle, but the recognition precision is affected.
  • Illuminated or dark images can be recognized, but the accuracy may be compromised.

Macao Resident ID Card OCR

  • 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.
  • An ID card to be recognized must occupy more than 50% of the image. When scanning an ID card, ensure that the entire ID card is displayed in the image.
  • Images can be rotated horizontally to any angle, but the recognition precision is affected.
  • Illuminated or dark images can be recognized, but the accuracy may be compromised.

Exit-Entry Travel Permit OCR

  • Only images in PNG, JPG, BMP, or TIFF format can be recognized.
  • No side of the image can be smaller than 15 or larger than 8,192 pixels.
  • An Exit-Entry Permit for Traveling to and from Hong Kong, Macao, and Taiwan to be recognized must occupy more than 50% of the image. When scanning a travel permit, ensure that the entire travel permit is displayed in the image.
  • Images can be rotated horizontally to any angle, but the recognition precision is affected.
  • Illuminated or dark images can be recognized, but the accuracy may be compromised.

Chinese Mainland Travel Permit OCR

  • Only images in PNG, JPG, BMP, or TIFF format can be recognized.
  • No side of the image can be smaller than 15 or larger than 8,192 pixels.
  • A Mainland Travel Permit for Hong Kong, Macao, and Taiwan Residents to be recognized must occupy more than 50% of the image. When scanning a travel permit, ensure that the entire travel permit is displayed in the image.
  • Images can be rotated horizontally to any angle, but the recognition precision is affected.
  • Illuminated or dark images can be recognized, but the accuracy may be compromised.