Whether it's regulatory texts, academic papers, or business contracts, PDF documents provide us with a convenient and stable method for information exchange. However, extracting text from PDF files is crucial for subsequent data analysis and content editing.
There are lots of solutions that allow effective separation of text information for further processing and analysis. However, text extraction is not a simple task. PDF files represent text as individual characters positioned on a page, rather than as readable lines or words. To extract meaningful text, programs must infer structure by analyzing character positions and reconstructing words, sentences, and paragraphs.
Using AI to extract text from PDF is a new technique to accurately extract text from various PDF documents, such as books, reports, letters, etc. We are going to introduce the popular AI tools for extracting PDF text. To build such an AI PDF text extractor, ComPDF will help and provide efficient text accuracy, using various algorithms, OCR, and AI. This article will delve into the technical challenges and solutions of PDF text extraction and demonstrate the solutions ComPDF offers.
Top Free Tools of AI Extract Text from PDF
1. Extract Text with PDF AI Tools
1.1 ComPDF AI（ComIDP）
ComPDF AI（ComIDP） can extract text from both PDF files and images. It offers a side-by-side view to compare the original and extracted content. The results are accurate and can be exported in plain text or JSON formats, which is useful for further processing.
1.2 ChatPDF
ChatPDF can extract text, but sometimes the order and meaning of the text are not correct.
1.3 PDF.AI
PDF.AI keeps the original layout and makes the text searchable. However, it does not allow you to export the text as a separate file.
1.4 ASKYourPDF
You can upload a file and ask questions about it. But it cannot extract and return the full text from the document. Its summary feature is also not very strong.
2. Extract Text from PDF with AI Chatting Tools
2.1 ChatGPT
ChatGPT can extract text from PDFs or images uploaded from your device or Google Drive. However, only one file can be uploaded per day unless you upgrade. It doesn’t show a preview of the text, and sometimes the download doesn’t work.
2.2 Gemini
Gemini lets you click on the extracted text to view it in the original file. It supports uploads from your device and Google Workspace. But it does not let you download the text as a separate file.
2.3 Qwen3
Qwen3 shows the original layout when previewing extracted text. It allows you to download the content as a TXT file. The extraction quality is generally good.
2.4 Perplexity
Perplexity extracts text along with other elements like lines or shapes. You cannot choose a specific output file type, but you can export the results as markdown, PDF, or DOCX. Sometimes, file exports may fail.
What Are the Hidden Pitfalls to Extract PDF Text with AI in Every PDF File Type
In this part, you will see why it is so hard to extract PDF text correctly. First, all PDF files need to address issues like text reading order (right-to-left, left-to-right, top-to-bottom), difficulties in splitting text into lines, identifying multiple languages, etc. Then, there are specific problems for extracting text from different types of PDF files, all of which ComPDF text extraction technology has resolved (See details in the next section). In this part, you can see the PDF types and text extraction challenges.
1. Programmatically Generated PDF: These PDFs are created on computers using W3C technologies like HTML, CSS, and JavaScript or other software such as Adobe Acrobat. Their text content is typically stored in the form of content streams. Such files can contain various components, such as images, text, and links, which are searchable and easy to edit. Issues in extracting text from such files include:
- Extracting text from content streams: Since these streams only indicate to the rendering engine what to draw on the screen, and because space is a non-entity, most of the time, we must infer spaces and line breaks ourselves. Hidden text, extra spaces or missing spaces, and ligatures all increase the difficulty of text extraction.
- Unsupported/unreadable characters: Some PDF documents may use uncommon or non-standard fonts or encodings that can cause text extraction tools to fail to recognize or display these characters correctly. For instance, some PDF documents might contain unreadable characters like “fo� P� �.”
2. Scanned PDFs: These files are merely collections of images stored within a PDF file. Elements within these images, such as text or links, cannot be selected or searched. Essentially, the PDF acts as a container for these images. This kind of file requires Optical Character Recognition (OCR) technology to recognize the image text and convert it into searchable and editable text. However, OCR technology can be affected by image quality, such as:
- Image shadows, noise interference, etc.: Poor quality of the scanned documents or equipment, or insufficient scanning environment lighting could lead to shadows, noise, and other interferences in the image, affecting the accuracy and quality of OCR.
- Image skew: If the scanned documents or equipment aren't positioned correctly, or if there's movement during scanning, this could result in the textual content in images being skewed, which could affect the accuracy and quality of OCR.
3. Documents Scanned with OCR: In such cases, documents are scanned, and OCR software is used to recognize the text in each image, converting it into searchable and editable text. These types of files have already undergone OCR recognition, but there may still be issues with accuracy. Any text extraction built on this may start with certain inaccuracies, such as:
- Mismatches between the text layer and the image layer, missing or incorrect text layers, incorrect text layer order, etc., all of which affect the quality and effectiveness of text extraction.
ComPDF Solutions to Extract PDF Text AI Method & Traditional Method
For text extraction technology, ComPDF offers the following two solutions that effectively address text extraction for all types of PDF files. For documents containing only text information, our non-intelligent solution can suffice. But for more complex documents and image-based ones, ComPDF Document AI offers higher accuracy in text extraction. To learn about the accuracy of ComPDF's information extraction, see this article.
1. Algorithm to Extract Text from PDF: X-Y Cut Recursion Projection
The X-Y Cut Recursion Projection Method is a top-down page segmentation technique that decomposes a document image into rectangular blocks. It employs a recursive approach by projecting along both the X and Y axes to segment a PDF into independent rectangles, facilitating the extraction of textual components. ComPDF utilizes this method for efficient text separation and structural organization, including rows, paragraphs, and columns, to retrieve characters, words, lines, and paragraphs from the document.
The advantage of the X-Y Cut Recursion Projection Method is its speed, making it suitable for simple, structured, non-image-based PDF documents. However, for complex, unstructured PDFs, there might be recognition errors or omissions.
2. ComPDF AI（ComIDP） - PDF AI Text Recognition and Extraction
ComPDF AI（ComIDP） is a solution for intelligent document processing supporting all types of PDF files, including image-based. It uses artificial intelligence-based methods for document recognition and analysis to extract textual information from PDF documents (as well as images, tables, etc.).
Intelligent Information Recognition and Parsing
ComPDF AI（ComIDP）’s PDF Text Recognition and Parsing technology combines traditional OCR with advanced recognition techniques to accurately identify and extract three key types of information:
Smart Text Extraction
- Accurately recognizes printed and handwritten text in over 70 languages
- Supports multiple scenarios, including documents, images, IDs, receipts, and road signs
- High accuracy even with rotated text and complex backgrounds
Smart Table Extraction
- Uses proprietary algorithms to analyze standard and non-standard tables
- Automatically detects headers, rows, and columns
- Saves data into separate sheets by table, page, or document
Smart Stamp Extraction
- Identifies stamps on contracts and receipts across different industries
- Extracts text from seals of various shapes and colors
- Handles single or overlapping seals with structured output
Intelligent Document Extraction
Uses key-value pair technology to extract specific fields from documents. Built-in models improve the accuracy and reliability of data extraction.
Intelligent Image Processing
- Distortion Correction: Detects image edges and automatically corrects skewed or distorted geometry such as tilting or perspective issues
- Image Enhancement: Sharpens and improves image quality to make text clearer and more readable
Which Formats Are Supported for Output after PDF Text Extraction
Data export refers to exporting the textual information extracted by ComPDF in various file formats, assisting in subsequent editing, analysis, presentation, etc. ComPDF supports converting PDF text into multiple files as follows:
- JSON: Store text as key-value pairs. It is easy to modify and it works well with many programming languages and systems.
- CSV: Save data in a table format using commas to separate values. Each line represents a data record. It's also structured data for you to analyze.
- RTF: Extract your text and store text with formatting, making it easy to edit and display content in a readable way.
- HTML (HyperText Markup Language): A hypertext markup language that can organize and store text information with tags, convenient for data display and interaction.
- Word: A common document processing software that can organize and store text information in document form, convenient for data editing and typesetting.
- Excel: A common spreadsheet file type that can organize and store text information in a table form and is convenient for data calculation and analysis.
- PPT (PowerPoint): A common presentation software that can organize and store text information in the form of slides, convenient for data presentation and exchange.
- TXT: Save extracted plain text content for lightweight usage and compatibility.
- Image (PNG/JPG): Export your PDF content as image files for visual archiving or display.
Conclusion
Click the following links to try the free demos and please feel free to contact the ComPDF team for inquiries. Moreover, we also provide other free online tools for you to convert PDF formats.