NI Vision
NI Vision Concepts Manual
NI Vision Concepts Manual
July 2007
372916F-01
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© National Instruments Corporation v NI Vision Concepts Manual
Contents
About This Manual
Conventions ...................................................................................................................xix
Related Documentation..................................................................................................xix
PART I
Vision Basics
Chapter 1
Digital Images
Definition of a Digital Image.........................................................................................1-1
Properties of a Digitized Image .....................................................................................1-2
Image Resolution.............................................................................................1-2
Image Definition..............................................................................................1-2
Number of Planes ............................................................................................1-3
Image Types...................................................................................................................1-3
Grayscale Images.............................................................................................1-4
Color Images ...................................................................................................1-5
Complex Images..............................................................................................1-5
Image Files.....................................................................................................................1-6
Internal Representation of an NI Vision Image.............................................................1-6
Image Borders................................................................................................................1-8
Image Masks ..................................................................................................................1-10
When to Use ....................................................................................................1-10
Concepts ..........................................................................................................1-10
Chapter 2
Display
Image Display ................................................................................................................2-1
When to Use ....................................................................................................2-1
Concepts ..........................................................................................................2-1
In-Depth Discussion ........................................................................................2-2
Display Modes ..................................................................................2-2
Mapping Methods for 16-Bit Image Display....................................2-2
Palettes ...........................................................................................................................2-4
When to Use ....................................................................................................2-4
Concepts ..........................................................................................................2-4
In-Depth Discussion ........................................................................................2-5
Contents
NI Vision Concepts Manual vi ni.com
Gray Palette ...................................................................................... 2-5
Temperature Palette.......................................................................... 2-6
Rainbow Palette................................................................................ 2-6
Gradient Palette ................................................................................ 2-7
Binary Palette ................................................................................... 2-7
Regions of Interest......................................................................................................... 2-8
When to Use.................................................................................................... 2-8
Concepts.......................................................................................................... 2-9
Nondestructive Overlay................................................................................................. 2-10
When to Use.................................................................................................... 2-10
Concepts.......................................................................................................... 2-11
Chapter 3
System Setup and Calibration
Setting Up Your Imaging System.................................................................................. 3-1
Acquiring Quality Images............................................................................... 3-3
Resolution......................................................................................... 3-3
Contrast............................................................................................. 3-5
Depth of Field................................................................................... 3-5
Perspective........................................................................................ 3-5
Distortion .......................................................................................... 3-7
Spatial Calibration ......................................................................................................... 3-7
When to Use.................................................................................................... 3-7
Concepts.......................................................................................................... 3-8
Calibration Process ........................................................................... 3-8
Coordinate System............................................................................ 3-9
Calibration Algorithms ..................................................................... 3-11
Calibration Quality Information ....................................................... 3-12
Image Correction .............................................................................. 3-13
Scaling Mode.................................................................................... 3-14
Correction Region............................................................................. 3-14
Simple Calibration ........................................................................... 3-16
Redefining a Coordinate System ...................................................... 3-17
