How to Read Table in Documents
Let’s talk about reading tables in documents. Extracting data from tables using plain Tesseract can be challenging, as the text often resides in cells and is sparsely scattered across the document. However, our library is equipped with a machine learning model that has been trained and fine-tuned for detecting and extracting table data accurately.
For simple tables, you can rely on straightforward table detection, while for more complex structures, our exclusive ReadDocumentAdvanced
method provides robust results, effectively parsing the table and delivering data.
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The following steps guide you in getting started with reading tables using IronOCR:
How to Read Table in Documents
- Download a C# library to extract data from tables
- Prepare the image and PDF document for extraction
- Set the ReadDataTables property to true to enable table detection
- Use the
ReadDocumentAdvanced
method for complex tables - Extract the data detected by these methods
Simple Table Example
Setting the ReadDataTables
property to true enables table detection using Tesseract. I created a simple table PDF to test this feature, which you can download here: 'simple-table.pdf'. Simple tables without merged cells can be detected using this method. For more complex tables, please refer to the method described below.
:path=/static-assets/ocr/content-code-examples/how-to/read-table-in-document-with-tesseract.cs
using IronOcr;
using System;
using System.Data;
// Instantiate OCR engine
var ocr = new IronTesseract();
// Enable table detection
ocr.Configuration.ReadDataTables = true;
using var input = new OcrPdfInput("simple-table.pdf");
var result = ocr.Read(input);
// Retrieve the data
var table = result.Tables[0].DataTable;
// Print out the table data
foreach (DataRow row in table.Rows)
{
foreach (var item in row.ItemArray)
{
Console.Write(item + "\t");
}
Console.WriteLine();
}
Imports Microsoft.VisualBasic
Imports IronOcr
Imports System
Imports System.Data
' Instantiate OCR engine
Private ocr = New IronTesseract()
' Enable table detection
ocr.Configuration.ReadDataTables = True
Dim input = New OcrPdfInput("simple-table.pdf")
Dim result = ocr.Read(input)
' Retrieve the data
Dim table = result.Tables(0).DataTable
' Print out the table data
For Each row As DataRow In table.Rows
For Each item In row.ItemArray
Console.Write(item & vbTab)
Next item
Console.WriteLine()
Next row
Complex Table Example
For complex tables, the ReadDocumentAdvanced
method handles them beautifully. In this example, we’ll use the 'table.pdf' file.
The ReadDocumentAdvanced
method requires the IronOcr.Extensions.AdvancedScan package to be installed alongside the base IronOCR package. Currently, this extension is only available on Windows.
Please note
:path=/static-assets/ocr/content-code-examples/how-to/read-table-in-document-with-ml.cs
using IronOcr;
using System.Linq;
// Instantiate OCR engine
var ocr = new IronTesseract();
using var input = new OcrInput();
input.LoadPdf("table.pdf");
// Perform OCR
var result = ocr.ReadDocumentAdvanced(input);
var cellList = result.Tables.First().CellInfos;
Imports IronOcr
Imports System.Linq
' Instantiate OCR engine
Private ocr = New IronTesseract()
Private input = New OcrInput()
input.LoadPdf("table.pdf")
' Perform OCR
Dim result = ocr.ReadDocumentAdvanced(input)
Dim cellList = result.Tables.First().CellInfos
This method separates the text data of the document into two categories: one enclosed by borders and another without borders. For the bordered content, the library further divides it into subsections based on the table's structure. The results are shown below. It is important to note that, since this method focuses on information enclosed by borders, any merged cells spanning multiple rows will be treated as a single cell.
Result

Helper Class
In the current implementation, the extracted cells are not yet organized properly. However, each cell contains valuable information such as X and Y coordinates, dimensions, and more. Using this data, we can create a helper class for various purposes. Below are some basic helper methods:
using System;
using System.Collections.Generic;
using System.Linq;
// A helper class to process table data by sorting cells based on coordinates
public static class TableProcessor
{
// Method to organize cells by their coordinates (Y top to bottom, X left to right)
public static List<CellInfo> OrganizeCellsByCoordinates(List<CellInfo> cells)
{
// Sort cells by Y (top to bottom), then by X (left to right)
var sortedCells = cells
.OrderBy(cell => cell.CellRect.Y)
.ThenBy(cell => cell.CellRect.X)
.ToList();
return sortedCells;
}
// Example method demonstrating how to process multiple tables
public static void ProcessTables(Tables tables)
{
foreach (var table in tables)
{
var sortedCells = OrganizeCellsByCoordinates(table.CellInfos);
Console.WriteLine("Organized Table Cells:");
// Initialize previous Y coordinate
int previousY = sortedCells.Any() ? sortedCells.First().CellRect.Y : 0;
foreach (var cell in sortedCells)
{
// Print a new line if the Y-coordinate changes, indicating a new row
if (Math.Abs(cell.CellRect.Y - previousY) > cell.CellRect.Height * 0.8)
{
Console.WriteLine(); // Start a new row
previousY = cell.CellRect.Y;
}
// Print the cell text followed by a tab
Console.Write($"{cell.CellText}\t");
}
Console.WriteLine("\n--- End of Table ---"); // End of a table
}
}
// Method to extract a specific row by the given index
public static List<CellInfo> ExtractRowByIndex(TableInfo table, int rowIndex)
{
if (table == null || table.CellInfos == null || !table.CellInfos.Any())
{
throw new ArgumentException("Table is empty or invalid.");
}
var sortedCells = OrganizeCellsByCoordinates(table.CellInfos);
List<List<CellInfo>> rows = new List<List<CellInfo>>();
// Group cells into rows based on Y coordinates
int previousY = sortedCells.First().CellRect.Y;
List<CellInfo> currentRow = new List<CellInfo>();
foreach (var cell in sortedCells)
{
if (Math.Abs(cell.CellRect.Y - previousY) > cell.CellRect.Height * 0.8)
{
// Store the completed row and start a new one
rows.Add(new List<CellInfo>(currentRow));
currentRow.Clear();
previousY = cell.CellRect.Y;
}
currentRow.Add(cell);
}
// Add the last row if it wasn't added yet
if (currentRow.Any())
{
rows.Add(currentRow);
}
// Retrieve the specified row
if (rowIndex < 0 || rowIndex >= rows.Count)
{
throw new IndexOutOfRangeException($"Row index {rowIndex} is out of range.");
}
return rows[rowIndex];
}
}
using System;
using System.Collections.Generic;
using System.Linq;
// A helper class to process table data by sorting cells based on coordinates
public static class TableProcessor
{
// Method to organize cells by their coordinates (Y top to bottom, X left to right)
public static List<CellInfo> OrganizeCellsByCoordinates(List<CellInfo> cells)
{
// Sort cells by Y (top to bottom), then by X (left to right)
var sortedCells = cells
.OrderBy(cell => cell.CellRect.Y)
.ThenBy(cell => cell.CellRect.X)
.ToList();
return sortedCells;
}
// Example method demonstrating how to process multiple tables
public static void ProcessTables(Tables tables)
{
foreach (var table in tables)
{
var sortedCells = OrganizeCellsByCoordinates(table.CellInfos);
Console.WriteLine("Organized Table Cells:");
// Initialize previous Y coordinate
int previousY = sortedCells.Any() ? sortedCells.First().CellRect.Y : 0;
foreach (var cell in sortedCells)
{
// Print a new line if the Y-coordinate changes, indicating a new row
if (Math.Abs(cell.CellRect.Y - previousY) > cell.CellRect.Height * 0.8)
{
Console.WriteLine(); // Start a new row
previousY = cell.CellRect.Y;
}
// Print the cell text followed by a tab
Console.Write($"{cell.CellText}\t");
}
Console.WriteLine("\n--- End of Table ---"); // End of a table
}
}
// Method to extract a specific row by the given index
public static List<CellInfo> ExtractRowByIndex(TableInfo table, int rowIndex)
{
if (table == null || table.CellInfos == null || !table.CellInfos.Any())
{
throw new ArgumentException("Table is empty or invalid.");
}
var sortedCells = OrganizeCellsByCoordinates(table.CellInfos);
List<List<CellInfo>> rows = new List<List<CellInfo>>();
// Group cells into rows based on Y coordinates
int previousY = sortedCells.First().CellRect.Y;
List<CellInfo> currentRow = new List<CellInfo>();
foreach (var cell in sortedCells)
{
if (Math.Abs(cell.CellRect.Y - previousY) > cell.CellRect.Height * 0.8)
{
// Store the completed row and start a new one
rows.Add(new List<CellInfo>(currentRow));
currentRow.Clear();
previousY = cell.CellRect.Y;
}
currentRow.Add(cell);
}
// Add the last row if it wasn't added yet
if (currentRow.Any())
{
rows.Add(currentRow);
}
// Retrieve the specified row
if (rowIndex < 0 || rowIndex >= rows.Count)
{
throw new IndexOutOfRangeException($"Row index {rowIndex} is out of range.");
}
return rows[rowIndex];
}
}
Imports Microsoft.VisualBasic
Imports System
Imports System.Collections.Generic
Imports System.Linq
' A helper class to process table data by sorting cells based on coordinates
Public Module TableProcessor
' Method to organize cells by their coordinates (Y top to bottom, X left to right)
Public Function OrganizeCellsByCoordinates(ByVal cells As List(Of CellInfo)) As List(Of CellInfo)
' Sort cells by Y (top to bottom), then by X (left to right)
Dim sortedCells = cells.OrderBy(Function(cell) cell.CellRect.Y).ThenBy(Function(cell) cell.CellRect.X).ToList()
Return sortedCells
End Function
' Example method demonstrating how to process multiple tables
Public Sub ProcessTables(ByVal tables As Tables)
For Each table In tables
Dim sortedCells = OrganizeCellsByCoordinates(table.CellInfos)
Console.WriteLine("Organized Table Cells:")
' Initialize previous Y coordinate
Dim previousY As Integer = If(sortedCells.Any(), sortedCells.First().CellRect.Y, 0)
For Each cell In sortedCells
' Print a new line if the Y-coordinate changes, indicating a new row
If Math.Abs(cell.CellRect.Y - previousY) > cell.CellRect.Height * 0.8 Then
Console.WriteLine() ' Start a new row
previousY = cell.CellRect.Y
End If
' Print the cell text followed by a tab
Console.Write($"{cell.CellText}" & vbTab)
Next cell
Console.WriteLine(vbLf & "--- End of Table ---") ' End of a table
Next table
End Sub
' Method to extract a specific row by the given index
Public Function ExtractRowByIndex(ByVal table As TableInfo, ByVal rowIndex As Integer) As List(Of CellInfo)
If table Is Nothing OrElse table.CellInfos Is Nothing OrElse Not table.CellInfos.Any() Then
Throw New ArgumentException("Table is empty or invalid.")
End If
Dim sortedCells = OrganizeCellsByCoordinates(table.CellInfos)
Dim rows As New List(Of List(Of CellInfo))()
' Group cells into rows based on Y coordinates
Dim previousY As Integer = sortedCells.First().CellRect.Y
Dim currentRow As New List(Of CellInfo)()
For Each cell In sortedCells
If Math.Abs(cell.CellRect.Y - previousY) > cell.CellRect.Height * 0.8 Then
' Store the completed row and start a new one
rows.Add(New List(Of CellInfo)(currentRow))
currentRow.Clear()
previousY = cell.CellRect.Y
End If
currentRow.Add(cell)
Next cell
' Add the last row if it wasn't added yet
If currentRow.Any() Then
rows.Add(currentRow)
End If
' Retrieve the specified row
If rowIndex < 0 OrElse rowIndex >= rows.Count Then
Throw New IndexOutOfRangeException($"Row index {rowIndex} is out of range.")
End If
Return rows(rowIndex)
End Function
End Module
Frequently Asked Questions
What is the main challenge of extracting data from tables in documents?
Extracting data from tables using plain Tesseract can be challenging because the text often resides in cells and is sparsely scattered across the document.
How can table data extraction be improved in documents?
Using a specialized library equipped with a machine learning model trained for detecting and extracting table data accurately can provide robust results even for complex table structures.
What steps are involved in getting started with reading tables using a specialized library?
To get started, download the appropriate C# library, prepare your document, set the relevant properties to enable table detection, use advanced methods for complex tables, and extract the data detected by these methods.
What is the purpose of enabling table detection properties?
Enabling table detection properties allows the library to identify and extract data from simple tables that do not have merged cells.
What is the advantage of using advanced methods for table detection?
Advanced methods provide enhanced table detection capabilities, handling complex tables effectively and separating text data into bordered and non-bordered categories.
What additional packages might be required for advanced table detection methods?
Advanced table detection methods may require additional extensions or packages to be installed alongside the base library.
How can you ensure compatibility with .NET Framework when using advanced features?
To ensure compatibility with .NET Framework, the project must run on x64 architecture, and the 'Prefer 32-bit' option should be unchecked in the project configuration.
What helper methods are available for processing extracted table data?
Helper methods such as organizing cells by coordinates, processing multiple tables, and extracting specific rows by index can assist in effectively handling and organizing extracted table data.
What information do the extracted cells contain?
Extracted cells contain valuable information such as X and Y coordinates, dimensions, and the text within the cell.