tesseract-ocr-lambda-function

AWS Lambda function that executes Tesseract (Optimal Character Recognition Engine) on Base 64 encoded images.
The function also implements horizontal whitespace detection through use of Tesseract's TSV output.

Dependencies

• Tesseract-OCR
  • Tesseract pre-compiled binaries for Amazon Linux 1 and Windows are included in this repo.
• Windows
  • Required for local testing.
• Python 3.7.5
  • Required for local testing.
  • The Tesseract Linux binary in this repo is only compatible with Amazon Linux 1, which corresponds to Lambda Python runtimes ≤ Version 3.7.5.

Testing

Local testing is supported only for Windows.
Modify /test_suite to add test cases.
Execute ocr_tester.py to run tests.

Usage

Include a Base 64 encoded image in the function invocation payload.
The function will return a JSON response with the following variables:

• text - String containing the recognized text or error info.
• statusCode - Integer representing function success status. See table below:

Result	Status Code
Success	200
Invalid Base 64	400
OCR error	500

Deployment

1. Create a ZIP file with the following structure (tested using 7 Zip):

    .
    ├── lambda_handler.py
    ├── ocr.py
    └── dependencies
        └── tesseract_ocr_linux

2. # for an AWS account.
3. Create S3 bucket.
4. Upload ZIP file to S3 bucket.
5. Create Lambda function.
6. Configure Lambda function with the following settings:

Setting	Value
Runtime	Python 3.7
Handler	lambda_handler.lambda_handler
Timeout	30+ seconds

7. Import source code from S3 bucket ZIP file.
8. Ready to use!