OCR (Optical Character Recognition)

Using OCR in Nitro PDF Pro

OCR (Optical Character Recognition) is a technology that converts scanned documents and images into editable and searchable text. It extracts text from non-editable content, such as scanned PDFs or images, so the user can search, edit, and reuse it in other applications. 

After OCR processing, the user can: 
• Search and select text 
• Use markup tools 
• Edit text (depending on the OCR mode) 

OCR adds an invisible text layer over the original document or image.

Run OCR on a document  

1. Open the PDF in Nitro PDF Pro  
2. On the Review tab, in the Document group, click the OCR button
3. In the OCR dialog box, select one option:   
   • Make Searchable: Enables text selection and markup  
   • Make Searchable and Editable: Enables text selection, markup, and editing 
4. To select pages for OCR, select Options
5. Click OK  

OCR a scanned document (automatic prompt)  

When you open a scanned PDF, Nitro PDF Pro may display a prompt:  

• Cancel: Do not run OCR   

• OCR Page: OCR the current page   

• OCR Document: OCR all pages  

Configure OCR Settings 

1. Go to Preferences on the Home page  
2. Select OCR  

OCR settings  

• Correct image skew: Straighten tilted pages  

• Detect text orientation: Rotate pages automatically  

• Use fixed threshold: Improve recognition for uneven backgrounds  

• Smooth color image: Reduce image noise and compression artifacts  

• Language: Select the document language  

• Quality:   
  • Low: Faster processing   
  • Medium: Balanced speed and accuracy   
  • High: Best accuracy, slower processing   
• Downsample images: Reduce image resolution after OCR  

• Image compression factor: Control file size vs quality   

• Select Retain text background to keep the text background 

Click Apply, then OK  

Scan and OCR a document  

1. On the Home tab, in the Create group, click PDF, then select From Scanner 
2. Select your scanner device  
3. In Scan Settings, select Make searchable or Make searchable and Editable
4. Click Advanced to configure OCR settings 
5. Click Apply and OK
6. Click  Scan  
7. Click Finish to complete scanning  

Improve OCR results  

• Use clear, high-quality scans  

• Align pages correctly when scanning  

• Increase contrast for faded documents  

• Deskew images if pages are tilted