Extracting Tables from Document Images using a Multi-stage Pipeline for Table Detection and Table Structure Recognition:

Overview

Multi-Type-TD-TSR

Check it out on Open In Colab Source Code of our Paper: Multi-Type-TD-TSR Extracting Tables from Document Images using a Multi-stage Pipeline for Table Detection and Table Structure Recognition

Description

Multi-Type-TD-TSR the Whole Pipeline

As global trends are shifting towards data-driven industries, the demand for automated algorithms that can convert digital images of scanned documents into machine readable information is rapidly growing. Besides the opportunity of data digitization for the application of data analytic tools, there is also a massive improvement towards automation of processes, which previously would require manual inspection of the documents. Although the introduction of optical character recognition (OCR) technologies mostly solved the task of converting human-readable characters from images into machine-readable characters, the task of extracting table semantics has been less focused on over the years. The recognition of tables consists of two main tasks, namely table detection and table structure recognition. Most prior work on this problem focuseson either task without offering an end-to-end solution or paying attention to real application conditions like rotated images or noise artefacts inside the document image. Recent work shows a clear trend towards deep learning approaches coupled with the use of transfer learning for the task of table structure recognition due to the lack of sufficiently large datasets. In this paper we present a multistage pipeline named Multi-Type-TD-TSR, which offers an end-to-end solution for the problem of table recognition. It utilizes state-of-the-art deep learning models for table detection and differentiates between 3 different types of tables based on the tables’ borders. For the table structure recognition we use a deterministic non-data driven algorithm, which works on all table types. We additionally present two algorithms. One for unbordered tables and one for bordered tables, which are the base of the used table structure recognition algorithm. We evaluate Multi-Type-TD-TSR on the ICDAR 2019 table structure recognition dataset and achieve a new state-of-the-art.

Multi-Type-TD-TSR on Fully Bordered Tables

For TSR on fully bordered tables, we use the erosion and dilation operation to extract the row-column grid cell image without any text or characters. The erosion kernels are generally thin vertical and horizontal strips that are longer than the overall font size but shorter than the size of the smallest grid cell and, in particular, must not be wider than the smallest table border width. Using these kernel size constraints results in the erosion operation removing all fonts and characters from the table while preserving the table borders. In order to restore the original line shape, the algorithm applies the dilation operation using the same kernel size on each of the two eroded images, producing an image with vertical and a second with horizontal lines. Finally, the algorithm combines both images by using a bit-wise ```or``` operation and re-inverting the pixel values to obtain a raster cell image. We then use the contours function on the grid-cell image to extract the bounding-boxes for every single grid cell.

Multi-Type-TD-TSR on Unbordered Tables

The TSR algorithm for unbordered tables works similarly to the one for bordered tables but utilizes the erosion operation in a different way. The erosion kernel is in general a thin strip with the difference that the horizontal size of the horizontal kernel includes the full image width and the vertical size of the vertical kernel the full image height. The algorithm slides both kernels independently over the whole image from left to right for the vertical kernel, and from top to bottom for the horizontal kernel. During this process it is looking for empty rows and columns that do not contain any characters or font. The resulting images are inverted and combined by a bit-wise ```and``` operation producing the final output. The output is a grid-cell image similar to the one from TSR for bordered tables, where the overlapping areas of the two resulting images represent the bounding-boxes for every single grid cell.

Multi-Type-TD-TSR on Partially Bordered Tables

The main goal of our algorithms for bordered and unbordered tables is to create a grid cell image by adding borders in the unbordered case and detecting lines in the bordered case. If a table is only partially bordered, then the unbordered algorithm is prevented to add borders in orthogonal direction to the existing borders, while the bordered algorithm can only find the existing borders. Both approaches result in incomplete grid cell images.


TSR for partially bordered tables uses the same erosion algorithm as in bordered tables to detect existing borderes, but without using them to create a grid cell, but to delete the borders from the table image to get an unbordered table. This allows for applying the algorithm for unbordered tables to create the grid-cell image and contours by analogy to the variants discussed above. A key feature of this approach is that it works with both bordered and unbordered tables: it is type-independent.

 

 

 

 

 

Table Structure Recognition Results

ICDAR 19 (Track B2)

IoU IoU IoU IoU Weighted
Team 0.6 0.7 0.8 0.9 Average
CascadeTabNet 0.438 0.354 0.19 0.036 0.232
NLPR-PAL 0.365 0.305 0.195 0.035 0.206
Multi-Type-TD-TSR 0.589 0.404 0.137 0.015 0.253

Instructions

Configurations

The source code is developed under the following library dependencies

  • PyTorch = 1.7.0
  • Torchvision = 0.8.1
  • Cuda = 10.1
  • PyYAML = 5.1

Detectron 2

The table detection model is based on detectron2 follow this installation guide to setup.

Image Alignment Pre-Processing

For the image alignment pre-processing step there is one script available:

  • deskew.py

To apply the image alignment pre-processing algorithm to all images in one folder, you need to execute:

python3 deskew.py

with the following parameters

  • --folder the input folder including document images
  • --output the output folder for the deskewed images

Table Structure Recognition (TSR)

For the table structure recognition we offer a simple script for different approaches

  • tsr.py

To apply a table structure recognition algorithm to all images in one folder, you need to execute:

python3 tsr.py

with the following parameters

  • --folder path of the input folder including table images
  • --type the table structure recognition type type in ["borderd", "unbordered", "partially", "partially_color_inv"]
  • --img_output output folder path for the processed images
  • --xml_output output folder path for the xml files including bounding boxes

Table Detection and Table Structure Recognition (TD & TSR)

To appy the table detection with a followed table structure recogniton

  • tdtsr.py

To apply a table structure recognitio algorithm to all images in one folder, you need to execute:

python3 tdtsr.py

with the following parameters

  • --folder path of the input folder including table images
  • --type the table structure recognition type type in ["borderd", "unbordered", "partially", "partially_color_inv"]
  • --tsr_img_output output folder path for the processed table images
  • --td_img_output output folder path for the produced table cutouts
  • --xml_output output folder path for the xml files for tables and cells including bounding boxes
  • --config path of detectron2 configuration file for table detection
  • --yaml path of detectron2 yaml file for table detection
  • --weights path of detectron2 model weights for table detection

Evaluation

To evaluate the table structure recognition algorithm we provide the following script:

  • evaluate.py

to apply the evaluation the table images and their labels in xml-format have to be the same name and should lie in a single folder. The evaluation could be started by:

python3 evaluate.py

with the following parameter

  • --dataset dataset folder path containing table images and labels in .xml format

Get Data

  • test dataset for table structure recognition including table images and annotations can be downloaded here
  • table detection detectron2 model weights and configuration files can be downloaded here

Citation

@misc{fischer2021multitypetdtsr,
    title={Multi-Type-TD-TSR - Extracting Tables from Document Images using a Multi-stage Pipeline for Table Detection and Table Structure Recognition: from OCR to Structured Table Representations},
    author={Pascal Fischer and Alen Smajic and Alexander Mehler and Giuseppe Abrami},
    year={2021},
    eprint={2105.11021},
    archivePrefix={arXiv},
    primaryClass={cs.CV}
}
Owner
Pascal Fischer
love machine learning, algorithms, probabilistic approaches, computer vision, natural language processing, robotics, 3D graphics and simulations.
Pascal Fischer
一键翻译各类图片内文字

一键翻译各类图片内文字 针对群内、各个图站上大量不太可能会有人去翻译的图片设计,让我这种日语小白能够勉强看懂图片 主要支持日语,不过也能识别汉语和小写英文 支持简单的涂白和嵌字

574 Dec 28, 2022
基于openpose和图像分类的手语识别项目

手语识别 0、使用到的模型 (1). openpose,作者:CMU-Perceptual-Computing-Lab https://github.com/CMU-Perceptual-Computing-Lab/openpose (2). 图像分类classification,作者:Bubbl

20 Dec 15, 2022
This is the code for our paper DAAIN: Detection of Anomalous and AdversarialInput using Normalizing Flows

Merantix-Labs: DAAIN This is the code for our paper DAAIN: Detection of Anomalous and Adversarial Input using Normalizing Flows which can be found at

Merantix 14 Oct 12, 2022
An interactive interface for using OpenCV's GrabCut algorithm for image segmentation.

Interactive GrabCut An interactive interface for using OpenCV's GrabCut algorithm for image segmentation. Setup Install dependencies: pip install nump

Jason Y. Zhang 16 Oct 10, 2022
Create single line SVG illustrations from your pictures

Create single line SVG illustrations from your pictures

Javier Bórquez 686 Dec 26, 2022
Python rubik's cube solver

This program makes a 3D representation of a rubiks cube and solves it step by step.

Pablo QB 4 May 29, 2022
Volume Control using OpenCV

Gesture-Volume-Control Volume Control using OpenCV Here i made volume control using Python and OpenCV in which we can control the volume of our laptop

Mudit Sinha 3 Oct 10, 2021
Fatigue Driving Detection Based on Dlib

Fatigue Driving Detection Based on Dlib

5 Dec 14, 2022
Geometric Augmentation for Text Image

Text Image Augmentation A general geometric augmentation tool for text images in the CVPR 2020 paper "Learn to Augment: Joint Data Augmentation and Ne

Canjie Luo 440 Jan 05, 2023
A curated list of resources dedicated to scene text localization and recognition

Scene Text Localization & Recognition Resources A curated list of resources dedicated to scene text localization and recognition. Any suggestions and

CarlosTao 1.6k Dec 22, 2022
A machine learning software for extracting information from scholarly documents

GROBID GROBID documentation Visit the GROBID documentation for more detailed information. Summary GROBID (or Grobid, but not GroBid nor GroBiD) means

Patrice Lopez 1.9k Jan 08, 2023
A curated list of promising OCR resources

Call for contributor(paper summary,dataset generation,algorithm implementation and any other useful resources) awesome-ocr A curated list of promising

wanghaisheng 1.6k Jan 04, 2023
A novel region proposal network for more general object detection ( including scene text detection ).

DeRPN: Taking a further step toward more general object detection DeRPN is a novel region proposal network which concentrates on improving the adaptiv

Deep Learning and Vision Computing Lab, SCUT 151 Dec 12, 2022
Official implementation of Character Region Awareness for Text Detection (CRAFT)

CRAFT: Character-Region Awareness For Text detection Official Pytorch implementation of CRAFT text detector | Paper | Pretrained Model | Supplementary

Clova AI Research 2.5k Jan 03, 2023
WACV 2022 Paper - Is An Image Worth Five Sentences? A New Look into Semantics for Image-Text Matching

Is An Image Worth Five Sentences? A New Look into Semantics for Image-Text Matching Code based on our WACV 2022 Accepted Paper: https://arxiv.org/pdf/

Andres 13 Dec 17, 2022
Motion detector, Full body detection, Upper body detection, Cat face detection, Smile detection, Face detection (haar cascade), Silverware detection, Face detection (lbp), and Sending email notifications

Security camera running OpenCV for object and motion detection. The camera will send email with image of any objects it detects. It also runs a server that provides web interface with live stream vid

Peace 10 Jun 30, 2021
Document manipulation detection with python

image manipulation detection task: -- tianchi function image segmentation salie

JiaKui Hu 3 Aug 22, 2022
OCRmyPDF adds an OCR text layer to scanned PDF files, allowing them to be searched

OCRmyPDF adds an OCR text layer to scanned PDF files, allowing them to be searched or copy-pasted. ocrmypdf # it's a scriptable c

jbarlow83 7.9k Jan 03, 2023
Implement 'Single Shot Text Detector with Regional Attention, ICCV 2017 Spotlight'

SSTDNet Implement 'Single Shot Text Detector with Regional Attention, ICCV 2017 Spotlight' using pytorch. This code is work for general object detecti

HotaekHan 84 Jan 05, 2022
Pytorch implementation of PSEnet with Pyramid Attention Network as feature extractor

Scene Text-Spotting based on PSEnet+CRNN Pytorch implementation of an end to end Text-Spotter with a PSEnet text detector and CRNN text recognizer. We

azhar shaikh 62 Oct 10, 2022