Example Code

Overview

This VI will open the file and first check that it is a valid PNG file.  Then it will loop through the file extracting a chunk on each iteration.  It then displays an array of these chunks so you can see what additional information is in the file.

Description

The PNG file format is a "chunk" based format.  Within the file are several chunks of data.  The most prominent is the "IDAT" chunk which contains the image itself but the format allows for additional header information to be embedded behind the file.  As an example of where this happens, ever wondered how VI snippets work?  They embed the code as part of this header information.

There are certain standard chunk types and the format is fixed so you get the size, type, data and CRC data for each chunk.  For technical details check the Wikipedia page.

Requirements

• LabVIEW 2012 (or compatible)

Steps to Implement or Execute Code

1. Run the VI.
2. Choose a valid PNG file.
3. Display an array of these chunks.

Additional Information or References 

Front Pane

VI Snippet 

**This document has been updated to meet the current required format for the NI Code Exchange.**