J4L PDF417 Vision for the Java Platform [TM]

• Introduction
• Installation
• Javadoc pages
• Examples

Installation

J4L PDF417 Vision is a Java component which can read (scan) pdf417 barcodes images. It support the following features:

• Finding all barcodes in large images (for example in a scanned page or document)
• Supports binary, text and numeric encoding.
• Supports Macro PDF 417 fields.

The requirements are:

• Java 1.4 or 1.5 (let us know if you need a version for 1.3 or 1.2)

Know limitations are:

• Best result are achieved with black barcodes on white background.
• Shadowed or blurred barcodes can be unreadable.
• Barcodes can be rotated but better results will be achieved in the upright position.

Installation

In order to use the component you only need to add rvision.jar and rpdf417vision.jar to your classpath. If you need to scan large images and get a outOfMemory error you will need to increase the Java heap Size using the Java.exe parameter -Xmx.

Javadoc pages

The Javadoc pages are located in the javadoc subdirectory of the component's ZIP file.

Examples

The use of the component is very simple. You must follow these steps:

1. Create PDF417Reader instance:
   
   PDF417Reader reader=new PDF417Reader();
   
   
   
2. Load your image into a BufferedImage class. The application PDF417Sample.java includes a method called loadImage() you can use for this purpose.
   
   Image image=loadImage("myFile.gif");
   
   
3. Create a RImage instance and call the read() method of the PDF417Reader
   
   PDF417Data[] barcodes=reader.scan(new RImage((BufferedImage) im));
   
   
4. Read the result array. The member of the array are PDF417Data objects which contain the following information:

• Value ( of the barcode) and position ( x , y).
• Confidence ( getConfidence() method): returns 0 if no errors have been detected, a value less than 0 if errors have been detected and a value >0 if errors have been detected and corrected. If the confidence is < 0 or >= than the Error Correction Level you can assume the read value is not correct.
• Error Correction Level (getECLevel() method). Returns the maximum number of errors that can be corrected.
• getMacroPDFField() allows you to read the Macro PDF 417 fields. See sample application PDF417Sample.java.
  
  If no barcode has been found the array returned by read() will be empty.
  

The component includes a simple test program called PDF417Sample.java that will scan all file located in the images subdiretory.

You can optimize the scanning process by setting some system properties:

• com.java4less.vision.maxarea=90000. Ignore objects larger than 90000 pixels.

• com.java4less.vision.minarea=30. Ignore objects smaller than 30 pixels.

• com.java4less.vision.minBarLength=15. Ignore start/stop bars shorter than 15pixels.

• com.java4less.vision.maxBarLength=1000. Ignore start/stop bars longer than 1000 pixels.

Depending on the size of the object and the image resolution you use, you can modify these values to speed up the scanning process.