PDF QR Code Reader – README

Features Overview

• Converts PDF pages into rasterized images
• Runs six decoding strategies for maximum detection success
• Stops immediately when a valid QR code is found
• Includes timeout protection and memory-safe operations
• Supports directory parameterization for Ghostscript installations
  
  

How It Works

The decoding engine processes the PDF in several stages. Each stage attempts to read a QR code from differently processed samples.

Decoding Pipeline (6 Steps)

1. Ghostscript (Original Image)
   Converts the first PDF page into a bitmap and attempts direct decoding.
2. Freeware Library (Original Image)
   Uses an alternative PDF ? PNG engine for a second decoding attempt.
3. Ghostscript + Light Preprocessing
   Crops margins, resizes, and converts to grayscale.
4. Ghostscript + Hard Preprocessing
   Applies stronger enhancements (upscaling, sharpening) to improve readability.
5. Freeware + Light Preprocessing
   Repeats the light preprocessing pipeline on the Freeware-rendered image.
6. Freeware + Hard Preprocessing
   Performs aggressive preprocessing on the Freeware-rendered image.

If a QR code is detected at any point, the process stops successfully.
If all attempts fail, a failure message is returned.

Additional System Protections

Timeout Control

A 60-second timeout ensures the process does not hang. If the threshold is reached, the operation returns a timeout message.

Memory-Safe Execution

All images, streams, and unmanaged resources are disposed of immediately to prevent memory leaks.

Ghostscript.NET Requirement

This extension relies on Ghostscript.NET to:

• Interpret PDF and PostScript® files
• Convert PDFs into rasterized images
• Ensure compatibility with internal processing modules
  
  

Installation Instructions

1) Download Ghostscript

Visit the official Ghostscript download page:

ghostscript.com/releases/gsdnld.html

Download the version appropriate for your server
(Recommended: Windows 64-bit).

2) Install Ghostscript

Example installation path:

C:\Program Files\gs\gs10.05.1\bin 

Directory Parameterization

This extension allows you to configure the Ghostscript installation directory.

Set the full path to the /bin directory containing the Ghostscript executable.

Example:

C:\Program Files\gs\gs10.05.1\bin 

System Purpose

Ghostscript.NET is used to:

• Interpret and convert PDF / PostScript files
• Produce rasterized output for decoding
• Maintain reliability when processing graphics and documents