Google Document Ai giving different outputs for the same file

Question

I was using Document OCR API to extract text from a pdf file, but part of it is not accurate. I found that the reason may be due to the existence of some Chinese characters.

The following is a made-up example in which I cropped part of the region that the extracted text is wrong and add some Chinese characters to reproduce the problem.

When I use the website version , I cannot get the Chinese characters but the remaining characters are correct.

When I use Python to extract the text, I can get the Chinese characters correctly but part of the remaining characters are wrong.

The actual string that I got.

Are the versions of Document AI in the website and API different? How can I get all the characters correctly?

---

Update:

When I print the detected_languages (don't know why for lines = page.lines , the detected_languages for both lines are empty list, need to change to page.blocks or page.paragraphs first) after printing the text, I get the following output.

Code:

from google.cloud import documentai_v1beta3 as documentai

project_id= 'secret-medium-xxxxxx'
location = 'us' # Format is 'us' or 'eu'
processor_id = 'abcdefg123456' #  Create processor in Cloud Console

opts = {}
if location == "eu":
    opts = {"api_endpoint": "eu-documentai.googleapis.com"}
client = documentai.DocumentProcessorServiceClient(client_options=opts)

def get_text(doc_element: dict, document: dict):
    """
    Document AI identifies form fields by their offsets
    in document text. This function converts offsets
    to text snippets.
    """
    response = ""
    # If a text segment spans several lines, it will
    # be stored in different text segments.
    for segment in doc_element.text_anchor.text_segments:
        start_index = (
            int(segment.start_index)
            if segment in doc_element.text_anchor.text_segments
            else 0
        )
        end_index = int(segment.end_index)
        response += document.text[start_index:end_index]
    return response

def get_lines_of_text(file_path: str, location: str = location, processor_id: str = processor_id, project_id: str = project_id):

    # You must set the api_endpoint if you use a location other than 'us', e.g.:
    # opts = {}
    # if location == "eu":
    #     opts = {"api_endpoint": "eu-documentai.googleapis.com"}

    # The full resource name of the processor, e.g.:
    # projects/project-id/locations/location/processor/processor-id
    # You must create new processors in the Cloud Console first
    name = f"projects/{project_id}/locations/{location}/processors/{processor_id}"

    # Read the file into memory
    with open(file_path, "rb") as image:
    image_content = image.read()

    document = {"content": image_content, "mime_type": "application/pdf"}

    # Configure the process request
    request = {"name": name, "raw_document": document}

    result = client.process_document(request=request)
    document = result.document

    document_pages = document.pages

    response_text = []
    # For a full list of Document object attributes, please reference this page: https://googleapis.dev/python/documentai/latest/_modules/google/cloud/documentai_v1beta3/types/document.html#Document

    # Read the text recognition output from the processor
    print("The document contains the following paragraphs:")
    for page in document_pages:
        lines = page.blocks
        for line in lines:
            block_text = get_text(line.layout, document)
            confidence = line.layout.confidence
            response_text.append((block_text[:-1] if block_text[-1:] == '\n' else block_text, confidence))
            print(f"Text: {block_text}")
            print("Detected Language", line.detected_languages)
    return response_text

if __name__ == '__main__':
    print(get_lines_of_text('/pdf path'))

It seems the language code is wrong, will this affect the result?

Answer 1

Posting this Community Wiki for better visibility .

One of features of DocumentAI is OCR - Optical Character Recognition which allows recognizing text from various files.

OP in this scenario received difference outputs using Try it function and Client Libraries - Python .

Why are there discrepancies between Try it and Python library ? It's hard to say as both methods use the same API documentai_v1beta3 . It might be related to some files modifications when pdf is uploading to Try it Demo , different endpoints, language alphabet recognition or some random stuff.

When you are using Python Client you also get accuracy % of text identification. Below examples from my testes:

However, OP's identification is about 0,73 so it might get wrong results and in this situation is a visible issue. I guess it cannot be anyhow improved using code. Maybe if there would be different quality of PDF (in shown OPs example there are some dots which might affect identification).