A scanned PDF is an image-based PDF created by scanning a paper document or taking a photo of it. Unlike a standard PDF, its text cannot be searched, selected, or read by screen readers unless Optical Character Recognition (OCR) and accessibility remediation are applied to make the document searchable and accessible.
Whether you’re digitizing legacy reports or capturing new contracts, scanned PDFs can create hurdles for accessibility. What exactly are these, and how can you make them accessible?
What is a Scanned PDF?
A scanned PDF document is essentially a picture of a page rather than a text-based file. When you place a paper document on a scanner or snap a photo with a mobile app, each page becomes a high‑resolution image. That image is then embedded into a PDF container. Unlike natively generated PDFs, text in the scanned version is not selectable or searchable until you apply OCR.
Difference Between PDF and Scanned PDF
| Feature | Normal PDF | Scanned PDF |
|---|---|---|
| Content Format | Text-based (selectable, searchable) | Image-based (non-selectable, non-searchable) |
| Created From | Word processors, spreadsheets, and export functions | Scanned from paper documents or photos |
| File Size | Usually smaller | Larger due to embedded images |
| Editability | Fully editable using PDF editors | Not editable unless OCR is applied |
| Search Functionality | Text is searchable | Text is not searchable without OCR |
| Accessibility | Can be made screen-reader friendly | Inaccessible unless tagged after OCR |
| OCR Requirement | Not required | Required to convert into searchable/editable text |
| Use Case Examples | E-books, digital reports, fillable forms | Scanned contracts, handwritten notes, old books |
How are Scanned PDFs Created?
Scanned PDFs are generated using a scanner or a mobile scanning app to capture each page of a paper document as high‑resolution images, which are then compiled into a single PDF file.
How to Convert a Scanned PDF to a Searchable/Editable One
- Search within the PDF
- Select and copy text
- Edit the content directly
Popular OCR solutions include:
- Adobe Acrobat Pro DC: Built‑in OCR with fine‑tuning options.
- Online OCR Tools: Quick alternatives such as OnlineOCR.net or iLovePDF.
Challenges When Making a Scanned PDF Accessible
Complex Layouts
Scanned PDFs often feature intricate layouts, including multi-column formats, tables, and overlapping text elements. Replicating these complex layouts while ensuring accessibility can be tricky, as it often requires careful content restructuring and organization to maintain visual appeal and logical flow.
Handwritten/Poor Quality Text
These scanned versions may contain handwritten or low-quality text, posing difficulties in accurate OCR recognition. Illegible or smudged text can hinder the conversion process, potentially resulting in errors in the extracted text.
Non-Standard Fonts or Encoding
Scanned PDFs sometimes employ non-standard fonts or character encodings, making accurate text recognition and representation challenging. Resolving font-related issues requires additional effort to ensure the document is accessible to screen readers and other assistive technologies.
Image-Based Content
They often incorporate images that convey crucial information, such as diagrams, graphs, or charts. And when these visuals do not have alt text or textual descriptions, they can be particularly inaccessible for screen reader users.
Complex Languages or Scripts
Scanned PDFs in languages with complex scripts, such as Arabic, Chinese, or Hebrew, pose accessibility challenges. Ensuring accurate recognition, proper reading order, and appropriate text direction for non-Latin scripts necessitates specialized expertise and tools.
Inaccessible Scanned Forms
Other forms of these scanned files, such as application forms or surveys, often lack interactive form fields or represent them as images. Converting these forms into accessible formats is a time-consuming and technically demanding process. Proper form field tagging and implementing accessibility features such as focus indicators and error notifications are essential.
Compliance With Accessibility Standards
Ensuring that remediated scanned PDFs meet accessibility standards and guidelines, such as the Web Content Accessibility Guidelines (WCAG) or specific government regulations like Section 508 in the USA, can be challenging. Meeting the requirements for document structure, alternative text, color contrast, and navigation while considering specific accessibility guidelines demands expert knowledge and a comprehensive approach.
Make Your PDFs Accessible With PREP!
Why is OCR Technology Needed for Scanned PDFs?
What is OCR Technology?
By applying this technology, the software adds a layer of real text on top of the image, making it possible to search, select, edit, copy, and paste the text directly from the OCR’d PDF document. It can also make existing PDFs editable and searchable for easy copy-paste actions and quick searches within the document.
How Does OCR Help Make Scanned PDFs Accessible?
- Text Recognition: OCR turns scanned images into editable, searchable text, making it accessible to assistive technologies.
- Screen Reader Compatibility: It makes scanned PDFs compatible with screen readers, enabling visually impaired users to access the content through the audio output.
- Text-to-Speech Conversion: This technology converts scanned text into a machine-readable format, enabling text-to-speech conversion for visually impaired individuals.
- Navigation and Searching: OCR creates searchable text layers in scanned PDFs, allowing users to navigate and search for specific information easily.
- Text Reflow: It extracts text from images so that content can reflow for better readability and accessibility.
- Alternative Text for Images: The text descriptions for images are extracted, which enables the creation of alternative text for visually impaired users.
- Metadata Extraction: OCR extracts metadata from scanned PDFs, providing crucial information for accessibility and organization.
- Language Recognition: It identifies the language in the scanned text, ensuring accurate language-specific accessibility features.
- Document Structure: OCR recognizes and preserves the document structure, aiding in navigation and understanding.
- Remediation Efficiency: It automates the extraction and conversion of text, significantly speeding up the remediation process for scanned PDFs.
How to Improve the Accessibility of Scanned PDFs
- Establish Logical Reading Order: Use proper document structuring techniques to create a clear hierarchy and facilitate navigation for screen reader users.
- Add Descriptive Alternative Text: Include alt-text for images to provide equivalent information to screen reader users.
- Enhance Color Contrast: Optimize color contrast between text and background to ensure easy readability for individuals with visual impairments.
- Implement Accessible Tables: Properly tag and format tables to ensure their interpretation and navigation by assistive technologies.
- Provide Meaningful Hyperlinks: Use descriptive link text that indicates the purpose or destination of the link.
- Include Bookmarks and Navigation Aids: Add bookmarks or a table of contents for easy navigation through the document.
- Ensure Compatibility With Assistive Technology: Test the accessibility of the PDF using different screen readers and assistive technologies.
- Follow Accessibility Standards and Guidelines: Adhere to recognized accessibility standards such as WCAG 2.1 or Section 508 to ensure compliance throughout the remediation process.
How Can PREP Help You Automate Scanned PDF Remediation?
- Instant OCR Conversion: PREP’s AI‑driven OCR instantly transforms each page of a scanned PDF into machine‑readable text, without the need for a separate OCR tool.
- Automated Tagging & Structure: It auto‑detects headings, tables, lists, and bookmarks, applying a logical tag tree for seamless navigation.
- Built‑in Compliance Checker: Real‑time validation against Section 508, WCAG 2.2, PDF/UA, and ADA standards flags and helps you fix issues on the fly.
- Collaboration & Scalability: As a cloud platform, PREP lets multiple users batch‑process hundreds of inaccessible PDF documents simultaneously, speeding team workflows.
- User‑Friendly Workflow: A streamlined three‑step process: Upload → Review & Modify → Export. Get fully compliant documents in minutes!
- Save Cost & Time: Automate up to 90% of remediation tasks, cut down manual work, and speed up delivery.
Automate the Accessibility Process With PREP!
Frequently Asked Questions (FAQs):
1. What is a scanned PDF?
A scanned PDF is an image-based PDF created by scanning a physical document or converting a photo into a PDF. Unlike a text-based PDF, its content is stored as images, so the text cannot be searched, copied, or edited unless OCR (Optical Character Recognition) is applied.
2. What is the difference between a scanned PDF and a normal PDF?
A normal PDF contains selectable and searchable text created from digital applications like Microsoft Word or Google Docs. A scanned PDF contains only images of document pages, making it non-searchable and inaccessible until OCR and accessibility remediation are performed.
3. Can a scanned PDF be searched or edited?
Not by default. Since scanned PDFs are image-based, you cannot search, copy, or edit the text. Applying OCR converts the images into machine-readable text, allowing you to search, select, and edit the content.
4. Does OCR make a scanned PDF fully accessible?
No. OCR converts image-based text into searchable text, but it does not make a PDF fully accessible. Additional remediation, such as adding document tags, correcting the reading order, providing alternative text for images, and ensuring proper table and heading structures, is required to meet accessibility standards like WCAG and PDF/UA.
5. How can I tell if a PDF is scanned?
A PDF is likely scanned if you cannot highlight or copy text, the search function does not find words, or screen readers cannot read the content properly. These are common signs that the document contains only images rather than digital text.
6. Why are scanned PDFs inaccessible to screen readers?
Screen readers rely on machine-readable text and document structure to interpret content. Since scanned PDFs contain only images, assistive technologies cannot identify or read the text unless OCR and accessibility remediation have been applied.
7. How do you make a scanned PDF accessible?
To make a scanned PDF accessible, first run OCR to create searchable text. Then add document tags, establish the correct reading order, include alternative text for images, create accessible tables and forms, verify document metadata, and test the file with accessibility checkers and screen readers.
8. What accessibility standards apply to scanned PDFs?
Accessible scanned PDFs should comply with standards such as WCAG 2.2, PDF/UA (ISO 14289), Section 508, and, where applicable, ADA Title II. These standards help ensure documents are usable by people who rely on assistive technologies.
