img2table is a table identification and extraction Python Library for PDF and images, based on OpenCV image processing
img2table
img2table is a simple, easy to use, table identification and extraction Python Library based on OpenCV image processing that supports most common image file formats as well as PDF files.
Thanks to its design, it provides a practical and lighter alternative to Neural Networks based solutions, especially for usage on CPU.
Table of contents
- Documents - Images - PDF - Supported OCRs - Table extraction - Excel exportInstallation
The library can be installed via pip:
| Command | Description | | --------------------------------- | ------------------------------------------- | | pip install img2table | Standard installation, supporting Tesseract | | pip install img2table[paddle] | For usage with Paddle OCR | | pip install img2table[easyocr] | For usage with EasyOCR | | pip install img2table[doctr] | For usage with docTR | | pip install img2table[surya] | For usage with Surya OCR | | pip install img2table[rapidocr] | For usage with RapidOCR | | pip install img2table[gcp] | For usage with Google Vision OCR | | pip install img2table[aws] | For usage with AWS Textract OCR | | pip install img2table[azure] | For usage with Azure Cognitive Services OCR |
Features
- Plug-and-play table extraction from heterogeneous documents, including native PDFs, scanned PDFs and images, with minimal configuration
- Handling of complex table structures such as merged cells
- Table content extraction by providing support for OCR services / tools
- Extracted tables are returned as a simple object, including a Pandas DataFrame representation
- Export extracted tables to an Excel file, preserving their original structure
Usage
Documents
Images
Images are instantiated as follows :
from img2table.document import Image
image = Image(src, detect_rotation=False)
Parameters
src : str, pathlib.Path, bytes orio.BytesIO, required
Image source
detect_rotation : bool, optional, default False
Detect and correct skew/rotation of the image
The implemented method to handle skewed/rotated images supports skew angles up to 45ยฐ and is
based on the publication by Huang, 2020.
Setting thedetect_rotationparameter toTrue, image coordinates and bounding boxes returned by other
methods might not correspond to the original image.
PDF files are instantiated as follows :
from img2table.document import PDF
pdf = PDF(src, pages=[0, 2], detect_rotation=False, pdftextextraction=True)
Parameters
src : str, pathlib.Path, bytes orio.BytesIO, required
PDF source
pages : list, optional, default None
List of PDF page indexes to be processed. If None, all pages are processed
detect_rotation : bool, optional, default False
Detect and correct skew/rotation of extracted images from the PDF
pdftextextraction : bool, optional, default True
Extract text from the PDF file for native PDFs
PDF pages are converted to images with a 200 DPI for table identification.
OCR
img2table provides an interface for several OCR services and tools in order to parse table content.
If possible (i.e for native PDF), PDF text will be extracted directly from the file and the OCR service/tool will not be called.
from img2table.ocr import TesseractOCR
ocr = TesseractOCR(n_threads=1, lang="eng", psm=11, tessdata_dir="...")
Parameters
n_threads : int, optional, default 1
Number of concurrent threads used to call Tesseract
lang : str, optional, default "eng"
Lang parameter used in Tesseract for text extraction
psm : int, optional, default 11
PSM parameter used in Tesseract, run tesseract --help-psmfor details
tessdata_dir : str, optional, default None
Directory containing Tesseract traineddata files. If None, the TESSDATA_PREFIXenv variable is used.
Usage of Tesseract-OCR requires prior installation. Check documentation for instructions.
For Windows users getting environment variable errors, you can check this tutorial_
PaddleOCR is an open-source OCR based on Deep Learning models.
At first use, relevant languages models will be downloaded.
from img2table.ocr import PaddleOCR
ocr = PaddleOCR(lang="en", kw={"kwarg": kw_value, ...})
Parameters
lang : str, optional, default "en"
Lang parameter used in Paddle for text extraction, check documentation for available languages
kw : dict, optional, default None
Dictionary containing additional keyword arguments passed to the PaddleOCR constructor.
EasyOCR is an open-source OCR based on Deep Learning models.
At first use, relevant languages models will be downloaded.
from img2table.ocr import EasyOCR
ocr = EasyOCR(lang=["en"], kw={"kwarg": kw_value, ...})
Parameters
lang : list, optional, default ["en"]
Lang parameter used in EasyOCR for text extraction, check documentation for available languages
kw : dict, optional, default None
Dictionary containing additional keyword arguments passed to the EasyOCR Readerconstructor.
docTR is an open-source OCR based on Deep Learning models.
from img2table.ocr import DocTR
ocr = DocTR(detect_language=False, kw={"kwarg": kw_value, ...})
Parameters
detect_language : bool, optional, default False
Parameter indicating if language prediction is run on the document
kw : dict, optional, default None
Dictionary containing additional keyword arguments passed to the docTR ocr_predictormethod.
RapidOCR is an open-source OCR based on ONNX Runtime.
from img2table.ocr import RapidOCR
ocr = RapidOCR(params={"Rec.langtype": ..., "kwarg": kwvalue, ...})
Parameters
params : dict, optional, default None
Dictionary containing configuration values passed to the RapidOCR constructor. If Rec.lang_typeis not provided, English is used by default.
Surya is an open-source OCR based on Deep Learning models.
At first use, relevant models will be downloaded.
from img2table.ocr import SuryaOCR
ocr = SuryaOCR(langs=["en"])
Parameters
langs : list, optional, default ["en"]
Lang parameter used in Surya OCR for text extraction
Authentication to GCP can be done by setting the standard GOOGLEAPPLICATIONCREDENTIALS environment variable.
If this variable is missing, an API key should be provided via the api_key parameter.
from img2table.ocr import VisionOCR
ocr = VisionOCR(apikey="apikey", timeout=15)
Parameters
api_key : str, optional, default None
Google Vision API key
timeout : int, optional, default 15
>API requests timeout, in seconds
When using AWS Textract, the DetectDocumentText API is exclusively called.
Authentication to AWS can be done by passing credentials to the TextractOCR class.
If credentials are not provided, authentication is done using environment variables or configuration files. Check boto3 documentation for more details.
from img2table.ocr import TextractOCR
ocr = TextractOCR(awsaccesskey_id="*", awssecretaccess_key="*", aws_sessi, region="eu-west-1")
Parameters
awsaccesskey_id : str, optional, default None
AWS access key id
awssecretaccess_key : str, optional, default None
AWS secret access key
awssessiontoken : str, optional, default None
AWS temporary session token
region : str, optional, default None
AWS server region
from img2table.ocr import AzureOCR
ocr = AzureOCR(endpoint="abc.azure.com", subscripti)
Parameters
endpoint : str, optional, default None
Azure Cognitive Services endpoint. If None, inferred from the COMPUTERVISIONENDPOINTenvironment variable.
subscription_key : str, optional, default None
Azure Cognitive Services subscription key. If None, inferred from the COMPUTERVISIONSUBSCRIPTION_KEYenvironment variable.
Table extraction
Multiple tables can be extracted at once from a PDF page/ an image using the extract_tables method of a document.
from img2table.ocr import TesseractOCR
from img2table.document import Image
Instantiation of OCR
ocr = TesseractOCR()
Instantiation of document, either an image or a PDF
doc = Image(src)
Table extraction
extractedtables = doc.extracttables(ocr=ocr,
implicit_rows=False,
implicit_columns=False,
borderless_tables=False,
min_confidence=50,
max_workers=1)
Parameters
ocr : OCRInstance, optional, default None
OCR instance used to parse document text. If None, cells content will not be extracted
implicit_rows : bool, optional, default False
Boolean indicating if implicit rows should be identified - check related example
implicit_columns : bool, optional, default False
Boolean indicating if implicit columns should be identified - check related example
borderless_tables : bool, optional, default False
Boolean indicating if borderless tables are extracted on top of bordered tables.
min_confidence : int, optional, default 50
Minimum confidence level from OCR in order to process text, from 0 (worst) to 99 (best)
max_workers : int, optional, default 1
Number of concurrent workers used for table extraction. Mainly useful for multi-page PDFs.
Method return
The ExtractedTable class is used to model extracted tables from documents.
Attributes
bbox : BBox
Table bounding box, with absolute coordinates and normalized coordinates available via bbox.relative
title : str
Extracted title of the table
content : OrderedDict
Dict with row indexes as keys and list of TableCellobjects as values
df : pd.DataFrame
Pandas DataFrame representation of the table
html : str
HTML representation of the table
In order to access bounding boxes at the cell level, you can use the following code snippet :
for id_row, row in enumerate(table.content.values()):
for id_col, cell in enumerate(row):
x1 = cell.bbox.x1
y1 = cell.bbox.y1
x2 = cell.bbox.x2
y2 = cell.bbox.y2
value = cell.value
Normalized coordinates (in percentage of image height / width) are also available on the same object:
relative_bbox = cell.bbox.relative
x1 = relative_bbox.x1
y1 = relative_bbox.y1
x2 = relative_bbox.x2
y2 = relative_bbox.y2
Images
extract_tables method from the Image class returns a list of ExtractedTable objects.
output = [ExtractedTable(...), ExtractedTable(...), ...]
extract_tables method from the PDF class returns an OrderedDict object with page indexes as keys and lists of ExtractedTable objects.
output = {
0: [ExtractedTable(...), ...],
1: [],
...
last_page: [ExtractedTable(...), ...]
}
Excel export
Tables extracted from a document can be exported to a xlsx file. The resulting file is composed of one worksheet per extracted table.
Method arguments are mostly common with the extract_tables method.
from img2table.ocr import TesseractOCR
from img2table.document import Image
Instantiation of OCR
ocr = TesseractOCR()
Instantiation of document, either an image or a PDF
doc = Image(src)
Extraction of tables and creation of a xlsx file containing tables
doc.to_xlsx(dest=dest,
ocr=ocr,
implicit_rows=False,
implicit_columns=False,
borderless_tables=False,
min_confidence=50,
max_workers=1)
Parameters
dest : str, pathlib.Pathorio.BytesIO, required
Destination for xlsx file
ocr : OCRInstance, optional, default None
OCR instance used to parse document text. If None, cells content will not be extracted
implicit_rows : bool, optional, default False
Boolean indicating if implicit rows should be identified - check related example
implicit_columns : bool, optional, default False
Boolean indicating if implicit columns should be identified - check related example
borderless_tables : bool, optional, default False
Boolean indicating if borderless tables are extracted.
min_confidence : int, optional, default 50
Minimum confidence level from OCR in order to process text, from 0 (worst) to 99 (best)
max_workers : int, optional, default 1
Number of concurrent workers used for table extraction. Mainly useful for multi-page PDFs.
Returns
If a io.BytesIO buffer is passed as dest arg, it is returned containing xlsx data
Examples
Several Jupyter notebooks with examples are available :
- Basic usage: generic library usage, including examples with images, PDF and OCRs
- Borderless tables: specific examples dedicated to the extraction of borderless tables
-
Implicit content: illustrated effect
of the parameter
implicitrows/implicitcolumnsof theextract_tablesmethod
FYI / Caveats
- For a high-level description of the implemented bordered and borderless table detection algorithms, see the table detection algorithms documentation.
- For table extraction, results are highly dependent on OCR quality. By design, tables where no OCR data can be found are not returned.
- The library is tailored for usage on documents with white/light background. Effectiveness can not be guaranteed on other type of documents.
- Table detection using only OpenCV processing can have some limitations. If the library fails to detect tables, you may check CNN / LLM based solutions.