PDF files are one of the most common formats used for storing and sharing documents, especially in workflows involving scanned receipts, invoices, forms, and ID cards. While they preserve formatting and are highly portable, they can quickly balloon in size—particularly when they contain high-resolution scans or embedded images.

For teams dealing with large volumes of documents, oversized PDFs can slow down processing, increase storage costs, and even lead to failed uploads when using document automation tools like OCR APIs. That’s where compression comes in.

In this guide, we’ll break down:

• What PDF compression is and why it matters
• Lossy vs. lossless compression
• Methods for compressing PDFs (manual, online, automated)
• How to compress PDFs using Python
• How compression fits into a data extraction pipeline

Why Compress PDFs?

Compression reduces a PDF’s file size while maintaining readability and structure. For document automation workflows, compression offers:

• Faster upload and processing times
• Improved performance in batch OCR jobs
• Reduced API latency and errors
• Lower storage and bandwidth usage

If you're using Mindee or another OCR API, compressing PDFs before submission can make your pipeline smoother and more reliable.

Lossy vs. Lossless Compression

There are two main strategies for compressing PDFs:

• Lossy compression removes some image or font data permanently. It can drastically reduce file size but may affect visual quality. Best for non-critical documents like reports or receipts.
• Lossless compression retains all original data. It shrinks file size without any quality loss. Ideal for sensitive documents like contracts or ID documents.

Choose the right method based on whether document fidelity is more important than file size.

Option 1: Manual Compression with Adobe Acrobat

Adobe Acrobat offers user-friendly compression tools:

1. Open your PDF in Adobe Acrobat.
2. Go to File > Save As Other > Reduced Size PDF.
3. Choose a compatible version (for broader access).
4. Click OK, then save your compressed PDF.

For more advanced options:

• Use PDF Optimizer under Advanced Tools to customize image resolution, font embedding, and metadata cleanup.

Option 2: Online PDF Compressors

If you need a quick fix and don't want to install software, online tools work well:

• Smallpdf: Simple drag-and-drop interface, free version available.
• iLovePDF: Offers compression along with merging, splitting, etc.
• PDF2Go: Provides both compression and basic editing.

⚠️ Privacy tip: Avoid uploading sensitive documents to online platforms. Check for SSL and automatic file deletion policies.

Option 3: Compress PDFs with Python (Great for Automation)

Python gives you full control over PDF compression in document pipelines.

Using pikepdf (lossless)

import pikepdf

pdf = pikepdf.open("input.pdf")
pdf.save("compressed.pdf", optimize_version=True)
pdf.close()

Using Ghostscript (command-line tool)

gs -sDEVICE=pdfwrite -dCompatibilityLevel=1.4 -dPDFSETTINGS=/ebook \
   -dNOPAUSE -dQUIET -dBATCH -sOutputFile=output.pdf input.pdf

Settings like /screen, /ebook, /printer, and /prepress offer different balances between quality and size.

✨ Pro tip: Integrate PDF compression as a pre-processing step before calling the Mindee API to reduce file size and API response time.

Image & Font Optimization for Better Compression

Large images and full font sets can bloat your PDFs. To reduce size:

• Resize and compress images before embedding
• Use JPEG for photos and PNG for simple graphics
• Subset fonts (embed only the characters used)
• Strip out metadata and unused objects

Tools like PDF Optimizer, qpdf, or Python scripts can help with these tasks.

Desktop vs. Online vs. Programmatic Tools

Choose based on your workflow: occasional users may prefer online tools, while dev teams benefit from automated solutions.

Compressing PDFs for OCR Workflows

When working with OCR APIs like Mindee, it’s best to:

• Use lossless compression for high-value documents
• Compress before sending files to the API
• Monitor file size thresholds for your API tier
• Consider compressing after scanning, before OCR, and again before long-term storage

Final Thoughts

PDF compression is a small step that makes a big difference in document automation. It speeds up workflows, reduces costs, and improves API performance.

Whether you're using Adobe tools, online platforms, or Python scripts, the key is balancing file size with content integrity.

By integrating compression into your Mindee-powered pipeline, you’ll gain both performance and peace of mind!